JP2008532426A - Diversity antenna control for telemetry of implantable medical devices - Google Patents

Abstract

  A far-field radio frequency (RF) telemetry system that communicates with an implantable medical device includes a diversity antenna system. In one embodiment, the antenna control circuit may transmit the output data frame and / or receive the response data frame based on the quality of the signal reception associated with the response data frame transmitted by the implantable medical device. Select the antenna of the diversity antenna system. In another embodiment, the antenna control circuit may select one of the diversity antenna systems to reduce potential data transmission errors associated with nulls encountered by telemetry systems due to environmental reflections of RF electromagnetic waves. Select multiple antennas.

Description

Related applications

(priority)
Claims priority to US patent application Ser. No. 11 / 068,476 filed Feb. 28, 2005 and US Patent Application No. 11 / 068,478 filed Feb. 28, 2005, which is hereby incorporated by reference. Incorporated in the description.

(Mutual citation of related applications)
This application is related to commonly assigned US patent application Ser. No. 11 / 068,497 entitled “DIVERSITY ANTENNA SYSTEM FOR COMMUNICATION WITH AN IMPLANTABLE MEDICAL DEVICE” filed on Feb. 28, 2005, This is incorporated herein by reference in its entirety.

  This document relates to telemetry systems for implantable medical systems, and more particularly to external telemetry systems having a diversity antenna in communication with an implantable medical device.

  Medical devices are implanted in the human body to monitor physiological conditions, diagnose disease, treat disease, or restore organ or tissue function. Examples of such implantable medical devices include cardiac rhythm management (CRM) devices, neurostimulators, neuromuscular stimulators, drug delivery devices, biological therapy devices. If an implantable medical device is intended for long-term use within a patient's body, its size and power consumption are limited by implantability and long-term requirements. As a result, many implantable medical devices rely on external systems that perform specific functions. Communication between the implantable medical device and the external system is performed via telemetry. Examples of specific telemetry functions include real-time physiological data acquired by an implantable medical device that retrieves the operational status of the implantable medical device, programs the implantable medical device to perform a specific monitoring or treatment task Sending data, and retrieving physiological data acquired and stored by the implantable medical device.

  One type of telemetry between an implantable medical device and an external system is based on inductive coupling between two closely placed coils and uses the mutual inductance between these coils. One of the coils is part of the implantable medical device and the other coil is part of the external system. This type of telemetry is called guided telemetry or near field telemetry. This is because the coils must be placed close together in order to obtain magnetically coupled communication.

  Far-field radio frequency (RF) telemetry provides another means of communication between an implantable medical device and an external system. Far-field RF telemetry is performed using an RF transceiver in the implantable medical device and an RF transceiver in the external system. Far-field RF telemetry frees the patient from attachment to body surfaces that limit mobility and is more appropriate to use when the patient is at home without the attendance of a physician or other professional caregiver .

  Far-field RF telemetry between implantable medical devices and external systems often operates in an environment where RF electromagnetic waves are reflected from various types of surfaces. As a result of the destructive interference between the incident wave and the reflected wave, the incident wave and the reflected wave cancel each other out. The far field RF telemetry link is severely interrupted when the antenna encounters a null. Such nulls move and are usually transient, but the disruption of the telemetry link may be long enough to cause data transmission errors.

  Therefore, it is necessary to ensure the quality of the far field RF telemetry between the external system and the embedded device when nulls are present.

  A far field RF telemetry system that communicates with an implantable medical device includes a diversity antenna system. In one embodiment, a multi-frame message, each containing multiple output data frames, is sent to the implantable medical device. In response, the implantable medical device transmits a response data frame after each one or more output data frames according to a predetermined communication protocol. The antenna control circuit selects an antenna of the diversity antenna system for transmission of the output data frame and / or reception of the response data frame based on the quality of signal reception associated with the response data frame. In another embodiment, the antenna control circuit selects one or more antennas of the diversity antenna system to reduce potential data transmission errors associated with nulls.

  In one embodiment, a system for communicating with an implantable medical device includes a diversity antenna system, a transceiver, an antenna interface circuit, and an antenna control circuit. The diversity antenna system includes a plurality of antennas that transmit output signals to the implantable medical device and receive input signals from the implantable medical device. The transceiver transmits the output data frame by modulating the output signal and receives the input data frame by demodulating the input signal. The antenna interface circuit includes a switch circuit that connects the antenna of the diversity antenna system to the transceiver according to the antenna selection signal. The antenna control circuit generates an antenna selection signal and includes an input signal monitoring timer, an input signal monitoring circuit, and an antenna selector. The input signal monitoring timer generates an input signal monitoring signal based on a predetermined communication protocol. The input signal monitoring circuit detects at least one quality measure of the input signal in response to each input signal monitoring signal and generates an indication of the quality of the input signal. The antenna selector adjusts the antenna selection signal based on the quality indication of the input signal.

  In one embodiment, a method for operating a telemetry system in communication with an implantable medical device is provided. A diversity antenna system is used to transmit the output signal to the implantable medical device and receive the input signal from the implantable medical device. The diversity antenna includes a plurality of antennas. By modulating the output signal, an output data frame is transmitted. An input data frame is received by demodulating the input signal. The antenna of the diversity antenna system is selected to be the active antenna according to the antenna selection signal. An input signal monitoring signal is generated based on a predetermined communication protocol. In response to each of the input signal monitoring signals, an input signal quality indication is generated by detecting at least one quality measure of the input signal. The antenna selection signal is adjusted based on the quality indication of the input signal.

  In one embodiment, the external system that communicates with the implantable medical device includes a diversity antenna system, a transceiver, an antenna interface circuit, and an antenna control circuit. The diversity antenna system includes a plurality of antennas that transmit output signals to the implantable medical device and receive input signals from the implantable medical device. The transceiver transmits the output data frame by modulating the output signal and receives the input data frame by demodulating the input signal. The antenna interface circuit includes a switch circuit that connects the antenna of the diversity antenna system to the transceiver according to the antenna selection signal. The antenna control circuit generates an antenna selection signal and includes a fading detector, an antenna selector, and an antenna switching timing circuit. The fading detector detects transmission faults that are associated with nulls. The antenna selector adjusts the antenna selection signal to connect the different antennas of the diversity antenna system to the transceiver in response to detecting a transmission failure. The antenna switching timing circuit suspends the antenna selection signal while an output data frame is being transmitted or an input data frame is being received.

  In one embodiment, a method for operating a telemetry system in communication with an implantable medical device is provided. A diversity antenna system that includes multiple antennas is used to transmit an output signal modulated by an output data frame to an implantable medical device, and the input signal modulated by the input data frame is transmitted from the implantable medical device. Receive. An active antenna is selected from the diversity antenna system according to the antenna selection signal. Detect transmission failures that are likely to be associated with nulls. In response to detecting a transmission failure, the antenna selection signal is adjusted to select a different active antenna of the diversity antenna system. While the frame of the output data frame is being transmitted or the frame of the input data frame is being received, the antenna selection signal is suspended. If no data frame is being transmitted or received, a different active antenna is selected from the diversity antenna system according to the adjusted antenna selection signal.

  In one embodiment, a telemetry system that communicates with an implantable medical device includes a diversity antenna system, a transceiver, an antenna interface circuit, and an antenna control circuit. The diversity antenna system includes a plurality of antennas that transmit output signals to the implantable medical device and receive input signals from the implantable medical device. The receiver transmits the output data frame by modulating the output signal and receives the input data frame by demodulating the input signal. The antenna interface circuit includes a switch circuit that connects the antenna of the diversity antenna system to the transceiver according to the antenna selection signal. The antenna control circuit includes a selection sequence generator that generates an antenna selection signal to select an antenna of the diversity antenna system to be connected to the transceiver in response to the antenna switching timing signal.

  In one embodiment, a method for operating a telemetry system in communication with an implantable medical device is provided. Use a diversity antenna system with multiple antennas to send an output signal modulated by the output data frame to the implantable medical device and receive an input signal modulated by the input data frame from the implantable medical device To do. An active antenna is selected from the diversity antenna system according to the antenna selection signal. An antenna selection signal is generated to select a new active antenna for the diversity antenna system at a predetermined period.

  In one embodiment, the external system that communicates with the implantable medical device includes a diversity antenna system, an external system controller, a transceiver, and an antenna control circuit. The diversity antenna system includes a plurality of antennas that transmit output signals to the implantable medical device and receive input signals from the implantable medical device. The transceiver transmits the output data frame by modulating the output signal and receives the input data frame by demodulating the input signal. The transceiver includes a plurality of receiving modules and a switch circuit. Each receive module has an input and an output coupled to the antenna of the diversity antenna system. The switch circuit connects one output of the reception module to the control device of the external system according to the reception path selection signal. The antenna control circuit generates a reception path selection signal and includes a signal quality evaluation circuit and a reception path selector. The signal quality evaluation circuit generates an indication of the quality of the input signal processed by each receiving module. The reception path selector adjusts the reception path selection signal based on the quality indication of the input signal generated for the plurality of reception modules.

  In one embodiment, a method for operating a telemetry system in communication with an implantable medical device is provided. A diversity antenna system that includes multiple antennas is used to transmit an output signal modulated by an output data frame to an implantable medical device, and the input signal modulated by the input data frame is transmitted from the implantable medical device. Receive. The input signal is processed through multiple processing paths, each coupled to an antenna of the diversity antenna system. A quality indication for the input signal processed by each processing path is generated. One of the processing paths is selected based on the quality indication detected in connection with the processing path.

  The above summary provides an overview of some of the teachings of the present application and does not deal exclusively or exhaustively with the subject matter of the present invention. Further details regarding the present subject matter are found in the following detailed description and claims. Other aspects of the present invention will become apparent to those skilled in the art upon reading, understanding, and viewing the drawings that form a part thereof, after reading the following detailed description. The scope of the present invention is defined by the claims and their legal equivalents.

  In the drawings, which are not necessarily shown to scale, like numerals indicate like components throughout the several views. The drawings generally illustrate various embodiments discussed herein by way of example.

  In the following detailed description, references are made to the accompanying drawings that form a part hereof, and in which are shown by way of illustration specific embodiments in which the invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention, and the embodiments are combined or other embodiments are used without departing from the spirit and scope of the invention. It should be understood that structural, logical and electrical changes can be made. The following detailed description provides examples, and the scope of the present invention is defined by the claims and their legal equivalents.

  It should be noted that when reference is made to “an”, “one” or “various” embodiments in this disclosure, it is not necessarily the same embodiment, and such references contemplate multiple embodiments. .

  This document discusses an RF telemetry system for two-way communication between an implantable medical device and an external system. The external system includes an external telemetry system that includes a diversity antenna system and an antenna control circuit that selects one or more active antennas of the diversity antenna system to ensure communication quality And use. An active antenna is an antenna currently used for transmitting and receiving signals. In one embodiment, the antenna control circuit selects one or more active antennas of the diversity antenna system to reduce or minimize data transmission errors associated with nulls. Null is a point that causes significant loss of RF telemetry such as disruption of data communication due to destructive interference. The antenna control circuit selects one or more active antennas based on the signal reception quality of the diversity antenna system. The signal transmitted to the implantable medical device includes a multi-frame message that includes a plurality of data frames. The implantable medical device transmits a response data frame after these transmitted one or more data frames. The antenna control circuit evaluates the quality of the signal reception if the external telemetry system is expected to receive the response data frame according to the communication protocol. In another embodiment, a different active antenna is selected upon detection of a transmission failure, such as a data transmission error or a sudden signal strength drop. Such transmission faults are related to nulls, which are the result of destructive interference between incident and reflected electromagnetic waves. In another embodiment, the new antenna is selected to be the active antenna regularly, such as periodically. This reduces the likelihood that the currently active antenna will encounter a null. In another embodiment, the telemetry system includes a plurality of processing paths, each associated with an antenna of a diversity antenna system. When a transmission failure is detected, a different processing path is selected.

  In various embodiments, the circuits described herein are implemented by hardware, software, firmware, or any combination thereof. In various embodiments, each of the circuits described herein, or portions thereof, is an application specific circuit that is constructed to perform one or more specific functions, and a program that performs such functions. General-purpose circuit, or a combination thereof.

  FIG. 1 is a diagram of an embodiment of a portion of a CRM system 100 and a portion of an environment in which the system 100 is used. System 100 includes an implantable medical device 110 and an external system 120. In the illustrated embodiment, the implantable medical device 110 is coupled to the patient's heart 102 through the lead system 105 after being implanted in the patient's body 101. Examples of implantable medical devices 110 include pacemakers, cardioverter / defibrillators, cardiac resynchronization therapy (CRT) devices, cardiac reconstruction control therapy (RCT) devices, neurostimulators, drug delivery systems, Includes biological therapy equipment, patient monitoring equipment. External system 120 allows a physician or other caregiver to interact with implantable medical device 110 through RF telemetry link 115, which provides two-way data communication between implantable medical device 110 and external system 120. provide.

  The RF telemetry link 115 performs data transmission from the implantable medical device 110 to the external system 120. This may include, for example, transmitting real-time physiological data acquired by the implantable medical device 110, retrieving physiological data acquired and stored by the implantable medical device 110, and stored in the implantable medical device 110. This includes retrieving treatment history data and retrieving data indicating the operating state of the implantable medical device 110 (for example, battery status or lead impedance). The RF telemetry link 115 also provides data transmission from the external system 120 to the implantable medical device 110. This may include, for example, programming the implantable medical device 110 to obtain physiological data, programming the implantable medical device 110 to perform at least one self-diagnostic test (eg, device operating state), at least Including programming the implantable medical device 110 to deliver one treatment.

  The RF telemetry link 115 is a far field telemetry link. The far field is also called the Fraunhofer region, and refers to a region where the component of the electromagnetic field generated by transmitting the electromagnetic radiation decays in proportion to 1 / r, where r is the observation point and the radiation source. Is the distance between. Thus, the far field refers to the region outside the r = λ / 2π boundary, where λ is the wavelength of electromagnetic energy transmitted. In one embodiment, the RF telemetry link 115 has a communication range (distance over which data can be wirelessly communicated) of at least 10 feet (3.1 m), but may be as long as possible with the communication technology used. Unlike an inductive telemetry link 115 that uses a coil that is placed near the implantable medical device 110, attached to a patient, and electrically connected to an external system 120 with a cable, using the RF telemetry link 115, The patient is free from physical constraints caused by the coils and cables, and the external system 120 can be placed completely away from the sterile location during surgery, such as implantation of the implantable medical device 110.

  The RF telemetry link 115 is supported by the implantable telemetry system of the implantable medical device 110 and the external telemetry system 122 of the external system 120. The external telemetry system 122 includes a diversity antenna system 126, an antenna interface circuit 128, a transceiver 130, and an antenna control circuit 132. Diversity antenna system 126 includes a plurality of antennas that transmit output signals to implantable medical device 110 and receive input signals from implantable medical device 110. The antenna interface circuit 128 includes a tuning circuit for the diversity antenna system 126 and routes output signals and input signals between the diversity antenna system 126 and the transceiver 130. The transceiver 130 transmits the output data frame by modulating the output signal and receives the input data frame by demodulating the input signal. Each of the output data frame and the input data frame is a frame that is a logical unit of data including a header, a payload, and a trailer. The header contains a “comma”, which contains a unique set of bits for signaling the reception of the frame. The absence of a comma or the inability to receive a comma indicates a frame reception failure. The payload contains the data block to be transmitted. The trailer includes a cyclic redundancy check (CRC) character having a value generated by the transmitter. The receiver receives the CRC character, recalculates the CRC character based on the received data block, and compares the result with the received CRC character in the trailer. If the recalculated CRC character matches the received CRC character, it is assumed that the data has been transmitted correctly. The CRC error indicates a mismatch between the recalculated CRC character and the received CRC character. Depending on the particular communication format, the header and trailer each contain additional information to flag, control data recovery, and / or synchronize the receiving device. In various embodiments, the output data frame includes a multi-frame message that each includes a plurality of data frames. The input data frames include response frames, each of which is an input data frame generated by implantable medical device 110 in response to one or more output data frames. The antenna control circuit 132 controls the operation of the antenna interface circuit for near optimal performance, or at least acceptable performance, of the diversity antenna system 126. In various embodiments, the antenna control circuit 132 selects an active antenna for the diversity antenna system 126 based on the quality of the input signal. Such quality is measured, for example, by the strength of the input signal and / or the integrity of the input data frame. The antenna control circuit 132 controls the timing for evaluating the quality of the input signal based on a predetermined communication protocol that is followed when performing bidirectional communication via the RF telemetry link 115. In one embodiment, the antenna control circuit 132 selects a different active antenna of the diversity antenna system 126 in response to detecting a transmission failure in the input signal. Such transmission failures are associated with null or damaged antennas or antennas with degraded performance. The external telemetry system 122 is connected to an external system controller 124, whereby the external system 120 receives information acquired by the implantable medical device 110 and controls the operation of the implantable medical device 110. The external system controller 124 receives an input data frame from the transceiver 130 and transmits an output data frame to the transceiver 130. The user interface 125 allows a physician or other caregiver to view the received information, enter commands and parameters, and control the operation of the CRM system 100.

  In one embodiment, external system 120 includes a programmer. In another embodiment, as shown in FIG. 2, the external system 120 includes a patient management system.

  FIG. 2 is a block diagram illustrating an embodiment of an external system 220 that is a specific embodiment of the external system 120. As shown in FIG. 2, the external system 220 is a patient management system that includes an external device 234, a telecommunications network 236, and one or more remote devices 238. The external device 234 includes an external telemetry system 122 that is located near the implantable medical device 110 and communicates with the implantable medical device 110 via the RF telemetry link 115. The one or more remote devices 238 are at one or more remote locations and communicate with the external device 234 through the network 236 so that a physician or other caregiver can monitor the patient from a distance to treat And / or access various treatment resources from one or more remote locations.

  FIG. 3 is a block diagram illustrating an embodiment of an external telemetry system 322 that is a specific embodiment of the external telemetry system 122. The external telemetry system 322 includes a diversity antenna system 326, an antenna interface circuit 328, a transceiver 330, and an antenna control circuit 332.

  Diversity antenna system 326 is a specific embodiment of diversity antenna system 126 and includes two or more antennas 340A-N. Each of the antennas 340A-N enables transmission of output signals to the implantable medical device 110 and / or reception of input signals from the implantable medical device 110. In one embodiment, diversity antenna system 126 includes two antennas. In certain embodiments, two antennas are mounted in a chassis of an external device such as a programmer or external device 234. In other embodiments, diversity antenna system 126 includes more than two antennas. An example of a diversity antenna system 126 is discussed in US patent application Ser. No. 11 / 068,497, entitled “DIVERSITY ANTENNA SYSTEM FOR COMMUNICATION WITH AN IMPLANTABLE MEDICAL DEVICE” filed on Feb. 28, 2005. The entirety is incorporated herein.

  Antenna interface circuit 328 is a specific embodiment of antenna interface circuit 128 and includes tuning circuits 342A-N and switch circuit 344. Tuning circuits 342A-N tune antennas corresponding to antennas 342A-N, respectively. The switch circuit 344 connects the antenna of the diversity antenna system 326 and the transceiver 330 in a controllable state according to the antenna selection signal. This antenna is used for transmitting output signals and receiving input signals. In one embodiment, the switch circuit 344 changes the connection between the antenna of the diversity antenna system 326 and the transceiver 330 to a connection between another antenna of the diversity antenna system 326 and the transceiver 330. Almost complete in about 50 microseconds to 1 millisecond.

  The transceiver 330 is a specific embodiment of the transceiver 130 and includes a modulator 346 and a demodulator 348. Modulator 346 generates an output signal by modulating an RF carrier with an output data frame, such as an output data frame that forms a multi-frame message. In one embodiment, the RF carrier frequency of the output signal ranges from about 902 MHz to 928 MHz, with about 914 MHz being a specific example. The data transmission rate of the output signal ranges from about 60 kilobits per second to 500 kilobits per second, with about 204.8 kilobits per second being a specific example. Demodulator 348 recovers the input data frame by demodulating the received input signal. The embedded telemetry circuit of the implantable medical device 110 generates an input signal by modulating another RF carrier with the input data frame. In one embodiment, the frequency of the RF carrier of the input signal ranges from about 902 MHz to 928 MHz, with about 914 MHz being a specific example. The data transmission rate of the input signal ranges from about 60 kilobits per second to about 500 kilobits per second, with about 102.4 kilobits per second being a specific example. The input data frame includes a response frame, each following one or more output data frames. In one embodiment, amplitude shift keying (ASK) is a modulation scheme used for both the output signal and the input signal. Modulator 346 is an ASK modulator and demodulator 348 is an ASK demodulator.

  The antenna control circuit 332 is a specific embodiment of the antenna control circuit 132 and generates an antenna selection signal. The antenna control circuit 332 includes an input signal monitoring timer 350, an input signal monitoring circuit 352, and an antenna selector 354. The input signal monitoring timer 350 generates an input signal monitoring signal based on a predetermined communication protocol. The communication protocol determines when to send output data frames and when to receive input data frames. Each of the input signal supervisory signals enables quality assessment of the input signal when it is scheduled to receive input data frames. The input signal monitoring circuit 352 generates an input signal quality indication by detecting at least one quality measure of the input signal in response to each input signal monitoring signal. Examples of quality measures include the presence of data transmission errors in the input signal and the strength of the input signal. The antenna selector 354 adjusts the antenna selection signal based on the quality indication of the input signal. In one embodiment, the antenna selector 354 connects the different antennas of the diversity antenna system 326 to the transceiver 330 when an expected input data frame is not detected within a scheduled reception time window. Adjust the antenna selection signal. In another embodiment, the antenna selector 354 adjusts the antenna selection signal to connect the different antennas of the diversity antenna system 326 to the transceiver 330 when a transmission error is detected from the input signal. In another embodiment, the antenna selector 354 connects the antenna of the diversity antenna system 326 to the transceiver 330 based on the strength of the input signal associated with each antenna of the diversity antenna system 326. Adjust the antenna selection signal.

  FIG. 4 is a block diagram illustrating an embodiment of an antenna control circuit 432 that is a specific embodiment of the antenna control circuit 332. The antenna control circuit 432 includes a non-responsive period timer 456, an input signal monitoring timer 450, an input signal monitoring circuit 452, and an antenna selector 454.

  The non-response period timer 456 starts a non-response period during transmission of a multi-frame message if it is expected to receive a response frame according to a predetermined communication protocol. The multi-frame message is transmitted on the active antenna of the diversity antenna system 326 connected to the transceiver 330. A response frame is expected to be received after some output data of the multi-frame message is transmitted according to a predetermined communication protocol. The non-response period is a maximum time interval in which the antenna selection signal can be adjusted without receiving a response frame in a state where there is no data transmission error. If the non-response period runs out before another active antenna is found that provides acceptable signal quality for the input signal, what is the first active transmission of the different frame, that is, the transmission of the multiframe message? Repeat transmission of multi-frame message using different antennas. In one embodiment, the non-response period is a predetermined time interval in the range of about 50 milliseconds to 1 second, with about 100 milliseconds being a specific example.

  Input signal monitoring timer 450 is a specific embodiment of input signal monitoring timer 350 and includes a response timer 458. The response timer 458 is transmitting a multi-frame message if it is expected to receive a response frame according to a predetermined communication protocol, and if there is one or more subsequent response frames, the reception is expected. The response time interval starts counting. That is, the response timer 458 clocks response time intervals each representing a time window in which a response frame is expected to be received. In one embodiment, the response time interval is a predetermined time interval in the range of about 4 milliseconds to 1 second, with about 100 milliseconds being a specific example. In one embodiment, the response time interval is set equal to the interval between the end of transmission of the output data frame and the start of transmission of the next output data frame.

  Input signal monitoring circuit 452 is a specific embodiment of input signal monitoring circuit 352 and includes a response fault detector 460. After the response timer 458 starts counting response time intervals, the response failure detector 460 detects response failures during the response time interval. A response failure is a data transmission error associated with a response frame. Examples of such data transmission errors include a response frame reception failure, a response frame comma reception failure, and a response frame CRC error. A specific example of a response fault detector 460 is discussed below with respect to FIG.

  Antenna selector 454 is a specific embodiment of antenna selector 354. During the non-response period, the antenna selector 454 may select an antenna to connect a different antenna of the diversity antenna system 326 to the transceiver 330 if a response failure is detected during a predetermined response time interval. Adjust the signal. If the input data frame is not successfully received during the non-response period and the non-response period is exhausted, the antenna selector 454 may select an antenna to connect the different antennas of the diversity antenna system 326 to the transceiver 330. Adjust the signal. Here, the different antenna refers to an antenna different from that from which the transmission of the multi-frame message is started.

  FIG. 5 is a block diagram illustrating an embodiment of response failure detector 560, which is a specific embodiment of response failure detector 460. In one embodiment, as shown in FIG. 5, the response failure detector 560 includes a lack of response detector 562, a lack of comma detector 564, and a CRC failure detector 566. In various other embodiments, the response failure detector 560 includes any one or more of a lack of response detector 562, a lack of comma detector 564, a CRC failure detector 566. A response failure is detected when any one or more of the missing response detector 562, the missing comma detector 564, and the CRC failure detector 566 detects a data transmission error associated with the response frame. The lack of response detector 562 detects response frames during the response time interval. A response failure is detected when no response frame is detected during the response time interval. The comma missing detector 564 detects a comma indicating receipt of a response frame during the response time interval. A response failure is detected when no comma is detected during the response time interval. CRC fault detector 556 detects CRC faults from the input signal during the response time interval. A response failure is detected when a CRC failure is detected during the response time interval.

  In other embodiments, the response failure detector 560 includes one or more error detectors that detect a different type of data transmission error than a response failure, a comma failure, or a CRC failure. Normally, the response failure detector 560 detects a predetermined type of data transmission error in the response frame in a state where the predetermined type of data transmission error indicates a response failure.

  FIG. 6 is a block diagram illustrating an embodiment of the antenna control circuit 632, which is another specific embodiment of the antenna control circuit 332. The antenna control circuit 632 includes a test frame generator 668, an input signal monitoring timer 450, an input signal monitoring circuit 452, and an antenna selector 654.

  Frame generator 668 generates an antenna test signal prior to transmission of the multi-frame message. The antenna test signal causes the transceiver 330 to transmit a test frame that is an output data frame. The response timer 458 starts counting the response time interval after transmitting the test frame. The response failure detector 460 detects a response failure during the response time interval.

  Antenna selector 654 is another specific embodiment of antenna selector 354. The antenna selector 654 adjusts the antenna selection signal to connect the different antennas of the diversity antenna system 326 to the transceiver 330 when a response failure is detected during the response time interval. In one embodiment, the test frame generator 668 uses an antenna test to transmit a test frame using different antennas of the diversity antenna system until an antenna associated with an acceptable quality input signal is found. Generate a signal. In another embodiment, if a response failure is detected from an input signal received using an antenna, the antenna is deselected as the only antenna associated with an unacceptable quality input signal. If the response failure is caused by a null encountered by the antenna, the probability that a different antenna will also encounter a null is minimized. In one embodiment, test frame generator 668 transmits test frames using different antennas of the diversity antenna system until the quality of the input signal is evaluated for all antennas of diversity antenna system 326. An antenna test signal for generating

  FIG. 7 is a block diagram illustrating an embodiment of the antenna control circuit 732, which is another specific embodiment of the antenna control circuit 332. The antenna control circuit 732 includes an input signal monitoring timer 450, an input signal monitoring circuit 452, and an antenna selector 754. The response timer 458 measures the response time interval when reception of a response frame is predicted according to a predetermined communication protocol. The response failure detector 460 detects a response failure during the response time interval.

  Antenna selector 754 is another specific embodiment of antenna selector 354. When a response failure is detected during transmission of a multi-frame message, the antenna selector 754 may connect the antenna of the diversity antenna system 326 to the transceiver 330 after transmission of the multi-frame message. Adjust the selection signal. Response failure detector 460 detects response failures during the transmission of multi-frame messages. If multiple response frames are expected to be received during the transmission of a multi-frame message, one response failure associated with any response frame causes the antenna selector 754 to transmit and receive different antennas in the diversity antenna system 326. The antenna selection signal is adjusted to connect to the device 330. The adjustment of the antenna selection signal is performed after the transmission of the multi-frame message is completed.

  FIG. 8 is a block diagram illustrating an embodiment of the antenna control circuit 832, which is another specific embodiment of the antenna control circuit 332. The antenna control circuit 832 includes a transmission period timer 870, an input signal monitoring timer 450, an input signal monitoring circuit 452, and an antenna selector 854.

  The transmission period timer 870 times the transmission period, each including a predetermined number of output data frames. The transmission period is determined based on a predetermined communication protocol, and is determined by the number of output data frames. The transmission period is sufficiently long so that at least one response frame is expected to be received during each transmission period. For example, if a maximum of five consecutive output data frames can be transmitted without a response frame being expected, it is determined that this transmission period includes at least six output data frames. The response timer 458 measures the response time interval when reception of a response frame is expected according to a predetermined communication protocol. The response failure detector 460 detects a response failure during the response time period.

  Antenna selector 854 is another specific embodiment of antenna selector 354. The antenna selector 854 adjusts the antenna selection signal to connect the different antennas of the diversity antenna system 326 to the transceiver 330 at the end of each transmission period if a response failure is detected during the transmission period. .

  FIG. 9 is a block diagram illustrating an embodiment of the antenna control circuit 932, which is another specific embodiment of the antenna control circuit 332. The antenna control circuit 932 includes an input signal monitoring timer 950, an input signal monitoring circuit 952, and an antenna selector 954.

  Input signal monitoring timer 950 is another specific embodiment of input signal monitoring timer 350 and includes a signal strength calculation timer 972. The signal strength calculation timer 972 generates a signal strength calculation signal before sending the multi-frame message.

  Input signal monitoring circuit 952 is another specific embodiment of input signal monitoring circuit 352 and includes a signal strength detector 974, a signal strength storage circuit 976, and a signal strength calculator 978. The signal strength detector 974 measures strength parameters that each represent the strength of the input signal associated with one antenna of the diversity antenna system 326. In one embodiment, the signal strength detector 974 measures a strength parameter associated with the antenna each time the antenna is selected to be an active antenna. The signal strength storage circuit 976 stores the measured strength parameter. Each stored intensity parameter is given a time stamp to indicate when the last measurement of that intensity parameter was performed. The signal strength calculator 978 calculates a signal strength index for each antenna of the diversity antenna system 326 in response to the signal strength calculation signal. The signal strength index is a function of the stored strength parameter and weighting factor. The weighting factor is a function of the time elapsed since the last measurement of the intensity parameter. Newer detected intensity parameters are given more weight in the calculation of the signal intensity index.

  Antenna selector 954 is another specific embodiment of antenna selector 354. The antenna selector 954 connects the antenna of the diversity antenna system 326 to the transceiver 330 based on the strength index calculated for all antennas of the diversity antenna system 326 in response to the signal strength calculation signal. Adjust the antenna selection signal. In one embodiment, the antenna selector 954 adjusts the antenna selection signal to select the antenna associated with the highest strength index.

  In various embodiments, the antenna control circuit 332 combines one or more antenna control circuits 432, 632, 732, 832, 932 as determined by one of ordinary skill in the art upon reading and understanding this document. In general, the antenna control circuit uses any of a variety of methods to evaluate the quality of the input signal, and the diversity antenna system antennas based on the quality of the input signal evaluated for this or different antennas, Choose to be an active antenna. In various embodiments, the probability that two or more antennas of a diversity antenna system will encounter a null simultaneously is negligible, so if one antenna is shown to be associated with an unacceptable quality input signal, 1 One or more different antennas may be associated with an acceptable quality input signal.

  FIG. 10 is a flow diagram illustrating an embodiment of a method 1000 for operating a telemetry system in communication with an implantable medical device. In one embodiment, the telemetry system includes a telemetry system 322.

  At 1010, a diversity antenna system that includes two or more antennas is used to transmit an output signal and receive an input signal. This includes transmitting the output data frame to the implantable medical device by modulating the output signal and receiving the input data frame from the implantable medical device by demodulating the input signal. In various embodiments, the transmitted output signal is modulated by a multi-frame message that includes a plurality of output data frames. In various embodiments, each multi-frame message includes two or more output data frames that are transmitted consecutively without interrupting the response frame.

  At 1020, an active antenna is selected according to the antenna selection signal. An active antenna is an antenna currently used for transmitting output signals and / or receiving input signals. The antenna selection signal specifies which antenna is active.

  At 1030, the antenna selection signal is adjusted based on the quality measure of the input signal. At 1032, an input signal monitoring signal is generated based on a predetermined communication protocol. This predetermined communication protocol specifies the transmission timing of the output data frame and the reception timing of the input data frame. The input signal monitoring signal indicates a time window in which the quality of the input signal is to be evaluated. At 1034, in response to the input signal monitoring signal, a quality indication is generated for the input signal associated with the antenna of the diversity antenna system. This quality indication is generated by detecting at least one quality measure of the input signal, such as the presence of transmission errors in the input signal and the strength of the input signal. At 1036, the antenna selection signal is adjusted based on the quality indication of the input signal. If the quality of the input signal is indicated as unacceptable, the antenna selection signal is adjusted to select a different antenna of the diversity antenna system as the active antenna. Specific exemplary embodiments of step 1030 are discussed below with respect to FIGS.

  FIG. 11 is a flow diagram illustrating an embodiment of a method 1100 for adjusting an antenna selection signal. Method 1100 is a specific embodiment of method 1000. In certain embodiments, method 1100 is performed by antenna control circuit 432.

  If a response frame is expected to be received according to a predetermined communication protocol during the transmission of the multi-frame message, a predetermined non-response period starts at 1110. The first antenna of the diversity antenna system is used to perform multi-frame message transmission. A response frame is expected to be received after transmitting more than one output data frame of the multi-frame message using the first antenna. In one embodiment, the predetermined non-response period ranges from about 50 milliseconds to 1 second, with 100 milliseconds being a specific example.

  During the transmission of a multi-frame message, if a response frame is expected to be received and there are one or more subsequent response frames, a predetermined response time interval begins at 1120 when each reception is expected. . In one embodiment, the predetermined response time interval ranges from about 4 milliseconds to 1 second, with about 100 milliseconds being a specific example. In one embodiment, the predetermined response time interval is limited by the time interval between the end of transmission of the output data frame and the start of transmission of the next output data frame.

  At 1130, a response failure is detected during a predetermined response time interval. A response failure is a data transmission error associated with a response frame. In one embodiment, the response frame is detected during a predetermined response time interval. If a response frame is not detected during a predetermined response time interval, a response failure is detected. In another embodiment, a comma indicating receipt of a response frame is detected during a predetermined response time interval. If no comma is detected during a predetermined response time interval, a response failure is detected. In another embodiment, a CRC failure in the response frame is detected during a predetermined response time interval. If a CRC failure is detected during a predetermined response time interval, a response failure is detected. In another embodiment, one or more of response frames, commas, CRC faults are detected. If no response frame is detected or no comma is detected or no CRC failure is detected during a predetermined response time interval, a response failure is detected.

  If a response failure is detected during a predetermined response time interval, at 1140, the antenna selection signal is adjusted to select a different antenna of the diversity antenna system to be the active antenna. If multiple response frames are expected to be received during transmission of a multi-frame message, a predetermined response time interval starts when each response frame is expected to be received, and during the predetermined response time interval If a response failure is detected, the antenna selection signal is adjusted to select a different antenna.

  When the predetermined non-response period has run out without successfully receiving the response frame, the antenna selection signal is adjusted at 1150 to select the second antenna of the diversity antenna system. The second antenna is an antenna different from the first antenna. In other words, if there is no data transmission error during the predetermined non-response period and no input data frame is received, repeat the transmission of a multi-frame message or execute another multi-frame message. To choose different antennas.

  FIG. 12 is a flow diagram illustrating an embodiment of a method 1200 for adjusting an antenna selection signal. Method 1200 is another specific embodiment of method 1000. In certain embodiments, method 1200 is performed by antenna control circuit 632.

  An antenna test signal is generated at 1210 prior to transmission of the multi-frame message. The antenna test signal causes the test frame to be transmitted to the implantable medical device, which transmits a response frame after receiving the test frame. After the transmission of the test frame, a response time interval predetermined at 1220 starts. A response failure is detected at 1230 during a predetermined response time interval. If a response failure is detected, the antenna selection signal is adjusted at 1240 to select a different antenna of the diversity antenna system to be the active antenna. In one embodiment, the method 1200 is repeated for all antennas in the diversity antenna system. In another embodiment, if a response failure is detected on the currently active antenna, method 1200 is repeated on another antenna. In another embodiment, if a response failure is detected with a currently active antenna, it is assumed that a different antenna is associated with an acceptable quality input signal and is therefore selected.

  FIG. 13 is a flow diagram illustrating an embodiment of a method 1300 for adjusting an antenna selection signal. Method 1300 is another specific embodiment of method 1000. In certain embodiments, method 1300 is performed by antenna control circuit 732.

  If a response frame is expected to be received during transmission of a multi-frame message, a response time interval predetermined at 1310 begins. A response failure is detected at 1320 during a predetermined response time interval. If a response failure is detected during transmission of a multi-frame message, the antenna selection signal is selected to select a different antenna of the diversity antenna system to become the active antenna after transmission of the multi-frame message at 1330. Adjust. If two or more response frames are expected to be received during the transmission of a multi-frame message, to select a different antenna to be the active antenna if there is one response failure associated with any response frame In addition, the antenna selection signal is adjusted.

  FIG. 14 is a flow diagram illustrating an embodiment of a method 1400 for adjusting an antenna selection signal. Method 1400 is another specific embodiment of method 1000. In certain embodiments, method 1400 is performed by antenna control circuit 832.

  In 1410, the transmission period is counted. The transmission period includes a period during which a predetermined number of output data frames are transmitted. While transmitting the output data frame to the implantable medical device, the transmission period is repeated and timed. The number of output data frames in a predetermined period is determined based on a predetermined communication protocol. During each transmission period, at least one response frame is expected to be received. If reception of a response frame is expected during the transmission period, a response time interval predetermined at 1420 starts. A response failure is detected at 1430 during a predetermined response time interval. If a response failure is detected during the transmission period, the antenna selection signal is adjusted to select a different antenna of the diversity antenna system to become the active antenna at 1440 at the end of the transmission period.

  FIG. 15 is a flow diagram illustrating an embodiment of a method 1500 for adjusting an antenna selection signal. Method 1500 is another specific embodiment of method 1000. In certain embodiments, method 1500 is performed by antenna control circuit 932.

  At 1510, each measures an intensity parameter associated with the antenna. Each strength parameter represents the strength of the input signal received by one antenna of the diversity antenna system. Examples of intensity parameters include input signal amplitude and power. At 1520, the intensity parameter is stored. Each stored intensity parameter is time stamped to indicate when the intensity parameter was measured. A signal strength calculation signal is generated at 1530 prior to transmission of the multi-frame message. At 1540, a signal strength index is calculated in response to the signal strength calculation signal. Each signal strength index is associated with one antenna of the diversity antenna system and is calculated based on the strength parameter and the weight factor. The weighting factor is a function of the time that has elapsed since the measurement of the intensity parameter. At 1550, an antenna selection signal is adjusted to select an antenna of the diversity antenna system to be an active antenna based on the signal strength index. In one embodiment, the antenna selection signal is adjusted to select the antenna that is associated with the highest signal strength index, that is, the most recently measured signal that is associated with the strongest input signal strength.

  Methods 1100, 1200, 1300, 1400, 1500 are specific exemplary implementations that illustrate how to time and perform input signal quality evaluation and how to adjust an antenna selection signal based on the evaluated input signal quality. It is a form. In various embodiments, these specific embodiments can be combined and other specific embodiments can be used, as determined by reading and understanding this document and determined by one of ordinary skill in the art. In general, any feasible method is used to evaluate the quality of the input signal, and the antenna of the diversity antenna system becomes the active antenna based on the quality of the input signal evaluated for this or different antennas. To choose.

  FIG. 16 is a block diagram illustrating an embodiment of external telemetry system 1622, which is a specific embodiment of external telemetry system 122. The external telemetry system 1622 includes a diversity antenna system 326, an antenna interface circuit 328, a transceiver 330, and an antenna control circuit 1632.

  The antenna control circuit 1632 is a specific embodiment of the antenna control circuit 132 and includes a fading detector 1650, an antenna selector 1652, and an antenna switching timing circuit 1654. Fading detector 1650 detects a transmission failure that is believed to be null related. Certain exemplary embodiments of fading detector 1650 are discussed below with respect to FIGS. The antenna selector 1652 adjusts the antenna selection signal to connect the different antennas of the diversity antenna system 326 to the transceiver 330 in response to detecting a transmission failure. The antenna switching timing circuit 1654 suspends the antenna selection signal while the frame of the output data frame is transmitted or the frame of the input data frame is received. Thus, if there is no data frame to be transmitted or received after the antenna selector 1652 adjusts the antenna selection signal, the connection between the diversity antenna system 326 and the transceiver 330 is changed. This prevents potential data transmission errors from occurring as a result of connection changes, ie switching from one antenna to another. In one embodiment, the antenna switch timing circuit 1654 delays adjustment of the antenna selection signal by the antenna selector 1652 until the transmission or reception of the data frame in progress is complete. In another embodiment, the antenna switch timing circuit 1654 suppresses the adjusted antenna selection signal from being provided to the switch circuit 344 until the transmission or reception of the data frame in progress is complete. In one embodiment, the antenna switching timing circuit 1654 is used only when the switching time for the switch circuit 344 to switch from one antenna to another is not significantly longer than the time required to transmit one data bit. Hold antenna selection signal while transmitting or receiving data frames. In another embodiment, external telemetry system 1622 includes an error protection circuit that prevents data transmission errors caused by the operation of switching circuit 344 in response to a change in antenna selection signal. The error protection circuit corrects errors detected in the received input data frame by executing an error correction algorithm.

  FIG. 17 is a block diagram illustrating an embodiment of external telemetry system 1722, which is a specific embodiment of external telemetry system 1622. The external telemetry system 1722 includes a diversity antenna system 326, an antenna interface circuit 328, a transceiver 330, and an antenna control circuit 1732.

  Antenna control circuit 1732 is a specific embodiment of antenna control circuit 1632 and includes an input frame failure detector 1750 and an antenna selector 1752. Input frame failure detector 1750 is a specific embodiment of fading detector 1650 and detects an input frame failure as a transmission failure from the input signal. An input frame failure includes a data transmission error in at least one input data frame. In one embodiment, one data transmission error within one input data frame constitutes a transmission failure that is associated with a null. The input frame failure detector 1750 includes a CRC failure detector 1756 and / or a comma missing detector 1758. A CRC failure detector 1756 detects a CRC failure from the input signal and indicates an input frame failure when a CRC failure is detected. The missing comma detector 1758 detects a comma indicating receipt of an input data frame during a predetermined time window and indicates an input frame failure if no comma is detected during the predetermined time window. In other embodiments, the input frame failure detector 1750 includes one or more error detectors that detect CRC failures and types of data transmission errors other than comma conclusions. Typically, the input frame failure detector 1750 detects a predetermined type of data transmission error within at least one input data frame and indicates an input frame failure when a predetermined type of data transmission error is detected. .

  Antenna selector 1752 is a specific embodiment of antenna selector 1652 for connecting different antennas of diversity antenna system 326 to transceiver 330 when input frame failure detector 1750 indicates an input frame failure. Adjust the antenna selection signal. In one embodiment, the antenna selector 1752 adjusts the antenna selection signal in response to the detection of a CRC fault or comma absence. In response to the adjusted antenna selection signal, switch circuit 344 receives the input signal and connects a different antenna to transceiver 330 to transmit the output signal until another input frame failure is indicated.

  FIG. 18 is a block diagram of an embodiment of an external telemetry system 1822, which is another specific embodiment of the external telemetry system 1622. The external telemetry system 1822 includes a diversity antenna system 326, an antenna interface circuit 328, a transceiver 330, and an antenna control circuit 1832.

  Antenna control circuit 1832 is a specific embodiment of antenna control circuit 1632 and includes a response fault detector 1850 and an antenna selector 1852. Response failure detector 1850 is a specific embodiment of fading detector 1650 and detects a response failure as a transmission failure from the input signal. The response failure includes a data transmission error in at least one response frame of the input data frame. The response frame is an input data frame generated and transmitted by the implantable medical device 110 in response to the output data frame transmitted to the implantable medical device 110. In one embodiment, one data transmission error within one response frame constitutes a transmission failure that is associated with a null. Response failure detector 1850 includes a CRC failure detector 1856 and / or a lack of response detector 1858. The CRC fault detector 1856 detects a CRC fault from the input signal, and indicates a response fault when a CRC fault is detected. The lack of response detector 1858 detects a response frame indicating receipt of an output data frame transmitted to the implantable medical device 110, and the response frame is detected during a predetermined time window starting from transmission of the output data frame. If not, it indicates a response failure.

  Antenna selector 1852 is a specific embodiment of antenna selector 1652 that adjusts the antenna selection signal to connect different antennas of diversity antenna system 326 to transceiver 330 when a response failure is indicated. . In one embodiment, the antenna selector 1852 adjusts the antenna selection signal in response to detecting a CRC fault or lack of response. In response to the adjusted antenna selection signal, the switch circuit 344 receives the input signal and connects a different antenna to the transceiver 330 to transmit the output signal until another response fault is indicated.

  FIG. 19 is a block diagram illustrating an embodiment of an external telemetry system 1922, which is another specific embodiment of the external telemetry system 1622. The external telemetry system 1922 includes a diversity antenna system 326, an antenna interface circuit 328, a transceiver 330, and an antenna control circuit 1932.

  The antenna control circuit 1932 is a specific embodiment of the antenna control circuit 163 and includes a signal strength fault detector 1950 and an antenna selector 1952. Signal strength fault detector 1950 is a specific embodiment of fading detector 1650 and detects a signal strength fault as a transmission fault from the input signal. The signal strength fault detected by the signal strength fault detector 1950 is caused by a null. The signal strength fault detector 1950 includes a signal strength detector 1960, a signal strength averaging circuit 1961, a threshold generator 1962, and a comparator 1964. The signal strength detector 1960 measures an strength parameter that is a measure of the strength of the input signal. In one embodiment, the intensity parameter is power measured in dBm (decibel ratio (log 10) from watts (W) to 1 milliwatt (1 mW)), and the signal intensity detector 1960 includes a signal power detector. In another embodiment, the intensity parameter is an amplitude measured in volts, and the signal intensity detector 1960 includes a signal amplitude detector. The signal strength averaging circuit 1961 calculates the average value of the measured strength parameters. In one embodiment, the signal strength averaging circuit 1961 calculates the average value of the strength parameter over a predetermined period. In another embodiment, the signal strength averaging circuit 1961 calculates the average value of the strength parameter over a predetermined number of frames. In certain embodiments, the predetermined number ranges from 4 to 50 frames, with approximately 6 frames being a specific example. The threshold generator 1962 dynamically generates a threshold intensity based on the average value of the measured intensity parameters. In one embodiment, the threshold intensity is generated by subtracting a predetermined margin from the average value of the measured intensity parameters. In one particular embodiment, the predetermined margin is in the range of about 10 dBm to 30 dBm, with about 20 dBm being a specific example. The comparator 1964 has an input unit that receives an average value of the measured intensity parameter, another input unit that receives a dynamically generated threshold intensity, and an average value of the measured intensity parameter is dynamically generated. An output unit that indicates a signal strength failure when the threshold strength falls below the threshold strength.

  The antenna selector 1952 is a specific embodiment of the antenna selector 1652 to connect different antennas of the diversity antenna system 326 to the transceiver 330 when the comparator 1964 indicates a signal strength failure. Adjust the antenna selection signal. In one embodiment, the antenna selector 1952 immediately adjusts the antenna selection signal in response to an indication of signal strength impairment. In another embodiment, the antenna selector 1952 may select the antenna when a signal strength failure is indicated in a predetermined time interval ranging from about 20 milliseconds to about 200 milliseconds, with about 50 milliseconds being a specific example. Adjust the signal. In response to the adjusted antenna selection signal, the switch circuit 344 connects the different antennas to the transceiver 330 to receive the input signal and transmit the output signal until another signal strength failure detection is indicated. To do.

  FIG. 20 is a block diagram illustrating an embodiment of an external telemetry system 2022, which is another specific embodiment of an external telemetry system 1622. The external telemetry system 2022 includes a diversity antenna system 326, an antenna interface circuit 328, a transceiver 330, and an antenna control circuit 2032.

  Antenna control circuit 2032 is a specific embodiment of antenna control circuit 1632 and includes a signal strength fault detector 2050 and an antenna selector 2052. The signal strength fault detector 2050 is another specific embodiment of the fading detector 1650 and detects a signal strength fault associated with the output signal as a transmission fault. The signal strength fault detector 2050 includes a signal strength receiver 2065 and / or an acknowledgment signal receiver 2066. The signal strength receiver 2065 receives a report frame that is an input data frame generated and transmitted by the implantable medical device 110 that detects a signal strength failure when receiving an output frame. Signal strength receiver 2065 indicates a signal strength failure if the reporting frame includes data indicating a signal strength failure associated with the output signal. Acknowledgment signal receiver 2066 receives an acknowledgment frame of the input data frame and transmits an output frame to implantable medical device 110, and if no acknowledgment frame is received within a predetermined time interval, Indicates strength disorder. The acknowledgment frame indicates that the implantable medical device 110 has successfully received the output frame.

  Antenna selector 2052 is a specific embodiment of antenna selector 1652 that adjusts the antenna selection signal to connect different antennas of diversity antenna system 326 to transceiver 330 when a signal strength failure is indicated. . In one embodiment, the antenna selector 2052 receives a data frame indicating a signal strength failure in the output signal as received by the implantable medical device 110 or responds to a lack of an acknowledgment frame. Then, the antenna selection signal is adjusted. In response to the adjusted antenna selection signal, the switch circuit 344 connects the different antennas to the transceiver 330 to receive the input signal and transmit the output signal until another signal strength failure detection is indicated. To do.

  FIG. 21 is a block diagram of an embodiment of an external telemetry system 2122, which is another specific embodiment of an external telemetry system 1622. The external telemetry system 2122 includes a diversity antenna system 326, an antenna interface circuit 328, a transceiver 330, and an antenna control circuit 2132.

  Antenna control circuit 2132 is a specific embodiment of antenna control circuit 1632 and includes a signal strength impairment detector 2150 and an antenna selector 2152. Signal strength impairment detector 2150 is another specific embodiment of fading detector 1650 that detects signal strength impairments associated with input and output signals. The signal strength fault detector 2150 includes an input signal strength fault detector 2168 and an output signal strength fault detector 2170. The input signal strength fault detector 2168 detects a signal strength fault related to the input signal as a transmission fault, and indicates an input signal strength fault when a signal strength fault is detected. In one embodiment, the input signal strength fault detector 2168 is substantially the same as or similar to the signal strength fault detector 1950. The output signal strength fault detector 2170 detects a signal strength fault related to the output signal as a transmission fault, and indicates an output signal strength fault when a signal strength fault is detected. In one embodiment, output signal strength fault detector 2170 is substantially the same as or similar to signal strength fault detector 2050.

  The antenna selector 2152 includes a reception antenna selector 2172 and a transmission antenna selector 2174. Receive antenna selector 2172 adjusts the antenna selection signal to select a different antenna of diversity antenna system 326 to receive the input signal when detection of input signal strength impairment is indicated. Transmit antenna selector 2174 adjusts the antenna selection signal to select a different antenna of diversity antenna system 326 to transmit the output signal when detection of output signal strength impairment is indicated. In one embodiment, two different antennas can be selected by an antenna selection signal. One is for receiving an input signal and the other is for transmitting an output signal. In another embodiment, the antenna selection signal may select one antenna or two different antennas to receive the input signal and transmit the output signal.

  In various other specific embodiments, fading detector 1650 includes input frame failure detector 1750, response failure detector 1850, signal strength failure detector 1950, signal strength failure detector 2050, signal strength failure detector 2150. One or more elements are selectively included. In one exemplary embodiment, fading detector 1650 includes an input frame failure detector 1750 (or a portion thereof) and a signal strength failure detector 1950 (or a portion thereof). The antenna selector 1752 adjusts the antenna selection signal in response to detection of an input frame failure or a signal strength failure. In another embodiment, fading detector 1650 includes an input frame failure detector 1750, a response failure detector 1850, and a signal strength failure detector 2150. The antenna selector 1752 adjusts the antenna selection signal in response to detecting any of the input frame failure, response failure, input signal strength failure, or output signal strength failure. Other embodiments, including such embodiments, will be apparent to those of skill in the art upon reading and understanding this document.

  FIG. 22 is a block diagram illustrating an embodiment of an external telemetry system 2222, which is another specific embodiment of the external telemetry system 122. The external telemetry system 2222 includes a diversity antenna system 326, an antenna interface circuit 328, a transceiver 330, and an antenna control circuit 2232.

  Antenna control circuit 2232 is another specific embodiment of antenna control circuit 132 and includes a selection sequence generator 2276 and a switching timer 2278. Selection sequence generator 2276 generates an antenna selection signal to select an antenna of diversity antenna system 326 to be connected to transceiver 330 in response to the antenna switching timing signal. The antenna is used for receiving input signals and transmitting output signals. In one embodiment, the selection sequence generator 2276 dynamically generates a random sequence and activates the antenna of the diversity antenna system 326 in response to the antenna switching timing signal according to the dynamically generated random sequence. A random sequence generator for generating an antenna selection signal is included for selection. In another embodiment, the selection sequence generator 2276 selects the antennas of the diversity antenna system 326 in response to the antenna switching timing signal according to a predetermined sequence, such as a built-in sequence or a programmed sequence. A predetermined sequence generator for generating an antenna selection signal is included. The switching timer 2278 generates an antenna switching timing signal according to a predetermined schedule that specifies a time for selecting a new antenna. In one embodiment, the predetermined schedule includes a predetermined period that ranges from about 50 milliseconds to 500 milliseconds, with about 200 milliseconds being a specific example. The switching timer 2278 periodically generates an antenna switching timing signal using this predetermined period. In one embodiment, the switch timer 2278 includes a switch hold circuit that holds an antenna switch timing signal while an output data frame frame is being transmitted or an input data frame frame is being received. This prevents data transmission errors that can be caused by switching from one antenna to another during transmission and reception of data frames. In one embodiment, the switch timer 2278 delays the generation of the antenna switch timing signal until the transmission or reception of the data frame being executed is complete. In another embodiment, the switching timer 2278 suppresses antenna change signal changes from being applied to the switch circuit 344 until the transmission or reception of the data frame in progress is complete.

  FIG. 23 is a block diagram illustrating an embodiment of an external telemetry system 2322, which is another specific embodiment of the external telemetry system 122. The external telemetry system 2322 includes a diversity antenna system 326, an antenna interface circuit 2328, a transceiver 2330, and an antenna control circuit 2332.

  Antenna interface circuit 2328 is a specific embodiment of antenna interface circuit 128 and includes tuning circuits 342A-N. Tuning circuits 342A-N tune the corresponding antenna among antennas 342A-N, respectively.

  The transceiver 2330 is a specific embodiment of the transceiver 130 and includes a plurality of receiving modules 2380A-N and a switch circuit 2382. Receiving modules 2380A-N each have an input coupled to the corresponding antenna of antennas 342A-N through the corresponding tuning circuit of tuning circuits 342A-N. The switch circuit 2382 connects the output unit of one of the reception modules 2380A to 2380N to the external system control device 124 according to the reception path selection signal. That is, the input signal processed by one of the reception modules 2380A to N is selected for use by the external system control device 124 according to the reception path selection signal.

  The antenna control circuit 2332 is a specific embodiment of the antenna control circuit 132 and generates a reception path selection signal. Rather than selecting one active antenna as in the case of external telemetry systems 1622-2222, more than one antenna 340A-N is active throughout the telemetry session. The antenna control circuit 2332 selects an effective antenna by selecting a reception path including the antenna. Each reception path includes antennas of antennas 340A-N, corresponding tuning circuits among tuning circuits 342A-N, and corresponding receiving modules among receiving modules 2380A-N. For example, one receive path includes an antenna 340A, a tuning circuit 342A, and a receive module 2380A. Selecting the reception path includes connecting an output unit of one of the reception modules 2380A to 2380N to the external system control device 124. The antenna control circuit 2332 includes a signal quality evaluation circuit 2384, a reception path selector 2386, and a path switching timing circuit 2388.

  The signal quality evaluation circuit 2384 generates an input signal quality instruction processed by each of the reception modules 2380A to 2380N. In the illustrated embodiment, the signal quality evaluation circuit 2384 includes an input frame failure detector 2390 and a signal strength detector 2392. In the input frame failure detector 2390, each of the reception modules 2380A to 2380N detects an input frame failure from the processing input signal. In one particular embodiment, the input frame failure detector 2390 detects a CRC failure from the received signal processed by each of the receiving modules 2380A-N, and if there is a receiving module in which the CRC failure is detected, the input frame failure A CRC fault detector is included. In another specific embodiment, the input frame failure detector 2390 detects commas indicating data frames from the input signal processed by each of the receiving modules 2380A-N during a predetermined time window and no commas are detected. If present, the module includes a comma missing detector adapted to indicate its input frame failure. The signal strength detector 2392 measures an intensity parameter that is a measure of the strength of the input signal processed by each of the receiving modules 2380A-N. In one embodiment, the signal strength detector 2392 includes an input signal strength failure detector that detects an input signal strength failure associated with the input signal processed by each of the receiving modules 2380A-N. In certain embodiments, the input signal strength fault detector is substantially the same as or similar to the signal strength fault detector 1950.

  Reception path selector 2386 adjusts the reception path selection signal based on the quality indication of the input signal generated for reception modules 2380A-N. The quality indication includes one or both of an input frame failure and an input signal strength failure. The reception path selector 2386 adjusts the reception path selection signal so as to deselect all reception paths in which at least one of the input frame failure and the input signal strength failure is detected. In one embodiment, receive path selector 2386 adjusts the receive path selection signal based on an intensity parameter measured for the receive path.

  The path switching timing circuit 2388 suspends the reception path selection signal while the frame of the output data frame is transmitted or the frame of the input data frame is received. This prevents data transmission errors that can be caused by switching from one receive path to another during transmission and reception of data frames. In one embodiment, the path switch timing circuit 2388 delays the adjustment of the receive path selection signal until the transmission or reception of the ongoing data frame is complete. In another embodiment, the path switch timing circuit 2388 inhibits a change in the receive path selection signal from being applied to the switch circuit 2382 until transmission or reception of the data frame being executed is complete.

  FIG. 24 is a flow diagram illustrating a method of operating a telemetry system that communicates with an implantable medical device. In one embodiment, the method is performed by an external telemetry system 1622 that includes the specific embodiments discussed herein.

  At 2400, a diversity antenna system that includes two or more antennas is used to transmit and receive signals. This includes transmitting an output signal to the implantable medical device and receiving an input signal from the implantable medical device. The output signal includes an RF carrier signal modulated with an output data frame by a telemetry system in communication with the implantable medical device. The input signal includes another RF carrier signal that is modulated with an input data frame by the implantable medical device. The input data frame is recovered by demodulating the received input signal. In one embodiment, ASK is a modulation scheme used to modulate output and input signals.

  At 2410, an active antenna is selected according to the antenna selection signal. An active antenna is an antenna currently used for transmitting and receiving signals. An antenna selection signal controls which one or more antennas of the diversity antenna system are active.

  At 2420, a transmission failure that is associated with a null is detected. Nulls are known to cause such transmission failures. Examples of transmission failures include input frame failures, response frame failures, and signal strength failures. One or more types of such transmission failures are detected as a null indication by a telemetry system in communication with the implantable medical device. Input frame failure is detected, for example, by detecting CRC failure or lack of commas from the input signal. Response frame failure is detected, for example, by detecting CRC failure or lack of response frame from the input signal. The response frame is transmitted from the implantable medical device in response to the output data frame transmitted to the implantable medical device. The lack of a response frame is detected within a predetermined period after the output data frame is transmitted to the implantable medical device. Signal strength impairments are detected by detecting a sudden drop in strength parameters such as, for example, the amplitude or power of the output signal and / or input signal. The intensity parameter is measured by a telemetry system in communication with the implantable medical device, by the implantable medical device, or both. In one embodiment, based on the signal strength of the output signal as measured and reported by the implantable medical device, a transmit antenna for transmitting the output signal to the implantable medical device is selected, and the implantable medical device and A receiving antenna that receives the input signal from the implantable medical device is selected based on the signal strength of the input signal as measured by the communicating telemetry system.

  If a transmission failure is detected, at 2430 the antenna selection signal is adjusted to select a different active antenna. That is, if a null is encountered, the telemetry system switches from the currently used antenna to a different antenna. It is very unlikely that the two antennas of the telemetry system will encounter a null at the same time.

  At 2440, the antenna selection signal is held during frame transmission / reception. In order to prevent data transmission errors, the antenna selection signal actually causes the antenna to switch when no data frame is transmitted or received. This is particularly important when the time required to complete the antenna switch is not significantly shorter than the time required to transmit and receive data bits. In one embodiment, when the time required to complete the antenna switch is significantly shorter than the time required to send and receive data bits, the antenna is switched while transmitting or receiving data frames. be able to. In another embodiment, the antenna can be switched while transmitting or receiving data frames if an error correction algorithm is running to correct potential data transmission errors.

  At 2450, a different active antenna is selected according to the adjusted antenna selection signal. This newly selected active antenna is used to transmit and receive data frames until another transmission failure is detected. During a telemetry session, steps 2420-2450 are repeated to continuously monitor transmission faults and switch to a different antenna if transmission faults are detected.

  FIG. 25 is a flow diagram illustrating another method of operating a telemetry circuit in communication with an implantable medical device. In one embodiment, the method is performed by external telemetry system 2222.

  At 2500, signals are transmitted and received using a diversity antenna system including two or more antennas. This includes transmitting the output signal to the implantable medical device and receiving the input signal from the implantable medical device, as discussed above for step 2400.

  At 2510, an active antenna is selected according to the antenna selection signal. An active antenna is an antenna currently used for transmitting and receiving antennas. The antenna selection signal controls which one or more antennas of the diversity antenna system are active.

  At 2520, an antenna selection signal is generated to select a new active antenna based on a predetermined schedule. That is, the antenna selection signal is adjusted at a time specified by a predetermined schedule. The antenna selection signal is adjusted according to an antenna selection sequence to reduce or minimize the probability that the telemetry system will encounter a null. Depending on how the antenna selection sequence is generated, the new active antenna may be the same antenna that is currently used or a different antenna. In one embodiment, the new active antenna is always different from the currently used antenna. In one embodiment, an antenna selection signal is generated based on a dynamically generated random sequence. In an alternative embodiment, the antenna selection signal is generated based on a predetermined sequence. In one embodiment, a new active antenna is selected periodically. In a further embodiment, the antenna selection signal is suspended while transmitting or receiving a frame.

  During the telemetry session, steps 2510-2520 are repeated to adjust the antenna selection signal at a predetermined time, such as a predetermined period. While the telemetry system communicates with the implantable medical device, both the location of the null and the position of the active antenna will vary, reducing the probability that the telemetry system will encounter a null.

  FIG. 26 is a flow diagram illustrating another method of operating a telemetry circuit in communication with an implantable medical device. In one embodiment, the method is performed by external telemetry system 2322.

  At 2600, a diversity antenna system that includes two or more antennas is used to transmit and receive signals. This includes transmitting the output signal to the implantable medical device and receiving the input signal from the implantable medical device, as discussed above for step 2400. Two or more antennas are used to receive input signals simultaneously.

  At 2610, the input signal is processed through multiple processing paths. In one embodiment, each of the plurality of processing paths includes a processing module, each coupled to one antenna of the diversity antenna system, which processes the input signal received by that antenna.

  At 2620, a quality indication of the input signal processed by each processing path is detected. As a result of the detection, quality indications are made, each associated with one of the processing paths. Examples of quality indications include the presence of input frame impairments and input signal strength impairments. Such a quality indication indicates that the telemetry system may have encountered a null. One or more types of such quality indications are detected by the telemetry system. An input frame failure is detected, for example, by detecting a CRC failure or a lack of commas from the input signal. Input signal strength impairments are detected by detecting a sudden drop in strength parameters such as the amplitude or power of the input signal.

  At 2630, a processing path is selected based on the detected quality indication. In one embodiment, the selection is valid while no data frame is being transmitted or received. During the telemetry session, steps 2620-2630 are repeated to continuously monitor the quality indication and switch to a different processing path if the quality indication indicates that the telemetry system has encountered a null.

  It should be understood that the foregoing detailed description is exemplary and not restrictive. For example, the implantable medical device can be any implantable medical device that can communicate with an external system or device via RF telemetry. Many other embodiments will be apparent to those of skill in the art upon reviewing the above description. Accordingly, the scope of the invention should be determined with reference to the appended claims and the full scope of equivalents of such claims.

1 is an illustration of an embodiment of a CRM system including an implantable medical device and an external system, a portion of an environment using the CRM system. FIG. FIG. 6 is a block diagram illustrating a specific embodiment of an external system. It is a block diagram which shows embodiment of the telemetry system of an external system. It is a block diagram which shows embodiment of the antenna control circuit of a telemetry system. FIG. 5 is a block diagram showing an embodiment of a response failure detector of the antenna control circuit of FIG. 4. It is a block diagram which shows another embodiment of an antenna control circuit. It is a block diagram which shows another embodiment of an antenna control circuit. It is a block diagram which shows another embodiment of an antenna control circuit. It is a block diagram which shows another embodiment of an antenna control circuit. 2 is a flow diagram illustrating an embodiment of a method for operating a telemetry system in communication with an implantable medical device. 3 is a flow diagram illustrating an embodiment of a method for adjusting an antenna selection signal. 5 is a flow diagram illustrating another method embodiment of adjusting an antenna selection signal. 5 is a flow diagram illustrating another method embodiment of adjusting an antenna selection signal. 5 is a flow diagram illustrating another method embodiment of adjusting an antenna selection signal. 5 is a flow diagram illustrating another method embodiment of adjusting an antenna selection signal. It is a block diagram which shows embodiment of the telemetry system of an external system. FIG. 17 is a block diagram illustrating a specific embodiment of the telemetry system of FIG. FIG. 17 is a block diagram illustrating another specific embodiment of the telemetry system of FIG. FIG. 17 is a block diagram illustrating another specific embodiment of the telemetry system of FIG. FIG. 17 is a block diagram illustrating another specific embodiment of the telemetry system of FIG. FIG. 17 is a block diagram illustrating another specific embodiment of the telemetry system of FIG. It is a block diagram which shows another embodiment of the telemetry system of an external system. It is a block diagram which shows another embodiment of the telemetry system of an external system. 2 is a flow diagram illustrating a method of operating a telemetry system in communication with an implantable medical device. 6 is a flow diagram illustrating another method of operating a telemetry system in communication with an implantable medical device. 6 is a flow diagram illustrating another method of operating a telemetry system in communication with an implantable medical device.

Claims (74)

A system for communicating with an implantable medical device,
A diversity antenna system including a plurality of antennas configured to transmit an output signal to the implantable medical device and receive an input signal from the implantable medical device;
A transceiver adapted to transmit an output data frame by modulating the output signal and to receive an input data frame by demodulating the input signal;
An antenna interface circuit including a switch circuit coupled between the diversity antenna system and the transceiver and adapted to connect an antenna of the diversity antenna system to the transceiver according to an antenna selection signal;
An antenna control circuit adapted to generate the antenna selection signal, the antenna control circuit comprising:
An input signal monitoring timer adapted to generate an input signal monitoring signal based on a predetermined communication protocol;
An input coupled to the input signal monitoring timer and adapted to generate a quality indication of the input signal by detecting at least one quality measure of the input signal in response to each of the input signal monitoring signals A signal monitoring circuit;
A system comprising: an input signal monitoring circuit; and an antenna selector coupled to the switch circuit and adapted to adjust the antenna selection signal based on the quality indication of the input signal.   The system of claim 1, wherein the switch circuit is adapted to connect the antenna of the diversity antenna system to the transceiver for transmitting the output signal and receiving the input signal.   The system of claim 1, wherein the transceiver is adapted to transmit a multi-frame message each including a plurality of data frames of the output data frame.   The input signal monitoring timer includes a response timer that starts counting a predetermined response time interval when reception of a response frame is expected according to the predetermined communication protocol, and the response frame includes the input data frame In response to one or more of the output data frames transmitted to the implantable medical device, wherein the input signal monitoring circuit causes a response failure during the predetermined response time interval. 4. The system of claim 3, comprising a response failure detector adapted to detect, wherein the response failure is a data transmission error associated with the response frame.   The response failure detector comprises a lack of response detector adapted to detect the response frame during the predetermined response time interval and the response frame is not detected during the predetermined response time interval The system of claim 4, wherein the response failure is detected.   The response failure detector comprises a comma missing detector adapted to detect a comma indicating receipt of the response frame during the predetermined response time interval, and the comma during the predetermined response time interval. 5. The system of claim 4, wherein the response failure is detected when no response is detected.   The response failure detector comprises a CRC failure detector adapted to detect a cyclic redundancy check (CRC) failure in the response frame during the predetermined response time interval, wherein the predetermined response time interval 5. The system of claim 4, wherein the response failure is detected when the CRC failure is detected.   The antenna control circuit further transmits one of the multi-frame messages on a first antenna of the diversity antenna system connected to the transceiver when the response frame is expected to be received. A non-response period timer for initiating a predetermined non-response period in between, wherein the response timer is expected to receive the response frame and each one or more subsequent response frames are expected to be received Adapted to start counting the predetermined response time interval during the one transmission of the multi-frame message, each of the subsequent response frames being one of the input data frames; The system of claim 4, responsive to one or more of the output data frames transmitted to the implantable medical device. Beam.   The antenna selector adjusts the antenna selection signal to connect different antennas of the diversity antenna system to the transceiver when the response failure is detected during the predetermined response time interval. If the input data frame is not received during the predetermined non-response period without the data transmission error, and the predetermined non-response period is exhausted, the diversity antenna system 9. The system of claim 8, adapted to adjust the antenna selection signal to connect a second antenna of the antenna to the transceiver.   The antenna control circuit further comprises a test frame generator that generates an antenna test signal that causes the transceiver to transmit a test frame of the output data frame before transmitting one of the multi-frame messages; The system of claim 4, wherein a response timer is adapted to begin counting the predetermined response time interval after the transmission of the test frame.   The antenna selector adjusts the antenna selection signal to connect different antennas of the diversity antenna system to the transceiver when the response failure is detected during the predetermined response time interval. 11. A system according to claim 10 adapted to:   5. The response timer of claim 4, wherein the response timer is adapted to start counting the predetermined response time interval during one transmission of the multi-frame message when the response frame is expected to be received. system.   If the antenna selector detects the response failure during the one transmission of the multi-frame message, the diversity antenna system differs after the one transmission of the multi-frame message. The system of claim 12, adapted to adjust the antenna selection signal to connect an antenna to the transceiver.   The antenna control circuit further includes a transmission period timer for measuring a transmission period including a period for transmitting a predetermined number of data frames of the output data frame, and the response timer is expected to receive the response frame. 5. The system of claim 4, wherein when adapted, the system is adapted to begin counting the predetermined response time interval during each of the transmission periods.   When the antenna selector detects the response failure during each of the transmission periods, a different antenna of the diversity antenna system is connected to the transceiver at the end of each of the response periods. 15. The system of claim 14, adapted to adjust the antenna selection signal to:   The system of claim 3, wherein the input signal monitoring timer includes a signal strength calculation timer adapted to generate a signal strength calculation signal prior to transmission of one of the multi-frame messages. The input signal monitoring circuit is
A signal strength detector that measures strength parameters each representing the strength of the input signal associated with one antenna of the diversity antenna system;
A signal strength storage circuit for storing the strength parameter;
In response to the signal strength calculation signal, each of the diversity parameters is associated with one of the strength parameters and based on the strength parameter and a weighting factor associated with the timing of the one of the strength parameters. 17. The system of claim 16, comprising a signal strength calculator that calculates a signal strength index associated with one antenna of the antenna system.   18. The antenna selector of claim 17, wherein the antenna selector is adapted to adjust the antenna selection signal to connect an antenna of the diversity antenna system to the transceiver based on the signal strength index. system. A system for communicating with an implantable medical device,
A diversity antenna system including a plurality of antennas configured to transmit an output signal to the implantable medical device and receive an input signal from the implantable medical device;
A transceiver adapted to transmit an output data frame by modulating the output signal and to receive an input data frame by demodulating the input signal;
An antenna interface circuit including a switch circuit coupled between the diversity antenna system and the transceiver and adapted to connect an antenna of the diversity antenna system to the transceiver according to an antenna selection signal; ,
An antenna control circuit adapted to generate the antenna selection signal, the antenna control circuit comprising:
A fading detector coupled to the transceiver and adapted to detect transmission faults associated with nulls;
An antenna coupled to the fading detector and adapted to adjust the antenna selection signal to connect different antennas of the diversity antenna system to the transceiver in response to detection of the transmission failure. A selector and
Coupled between the antenna selector and the switch circuit to hold the antenna selection signal while the frame of the output data frame is transmitted or the frame of the input data frame is received And an antenna switching timing circuit adapted to the system.   20. The system of claim 19, wherein the switch circuit is adapted to connect the antenna of the diversity antenna system to the transceiver for transmitting the output signal and receiving the input signal.   The fading detector comprises an input frame failure detector adapted to detect an input frame failure that is a data transmission error in at least one frame of the input data frame from the input signal; 20. The system of claim 19, wherein the antenna selector is adapted to adjust the antenna selection signal to connect the different antennas of the diversity antenna system to the transceiver. .   The input frame failure detector detects a cyclic redundancy check (CRC) failure from the input data frame, and when the CRC failure is detected, a CRC failure detector adapted to indicate the input frame failure The system of claim 21, comprising:   The input frame failure detector detects a comma indicating reception of the frame of the input data frame during a predetermined time window, and the input frame is detected when the comma is not detected during the predetermined time window; The system of claim 21, comprising a comma deficiency detector adapted to indicate a fault.   The fading detector comprises a response failure detector adapted to detect a response failure that is a data transmission error in at least one response frame of the input data frame, the at least one response frame comprising the output Responsive to transmission of a frame of data frames, the antenna selector transmits the antenna selection signal to connect the different antennas of the diversity antenna system to the transceiver when the response failure is indicated. The system of claim 19 adapted to adjust.   The response failure detector detects at least one response frame of the input data frame during a predetermined time interval starting with transmission of the frame of the output data frame, and the response frame is not detected 26. The system of claim 24, further comprising a lack of response fault detector adapted to indicate the response fault.   The response failure detector detects a cyclic redundancy check (CRC) failure in the at least one response frame of the input data frame after transmission of the frame of the output data frame, and the CRC failure is detected 25. The system of claim 24, further comprising a CRC fault detector adapted to indicate the response fault.   The fading detector comprises a signal strength fault detector adapted to detect at least one signal strength fault of the input signal and the output signal, wherein the antenna selector detects the signal strength fault. 20. The system of claim 19, wherein the system is adapted to adjust the antenna selection signal to connect the different antennas of the diversity antenna system to the transceiver. A signal strength detector, wherein the signal strength fault detector measures a strength parameter that is a measure of the strength of the input signal;
A threshold generator coupled to the signal intensity detector to dynamically generate a threshold intensity based on the measured intensity parameter;
A first input for receiving the measured intensity parameter and a second input for receiving the dynamically generated threshold intensity; and the measured intensity parameter is generated dynamically 28. The system of claim 27, comprising a comparator having an output that indicates the signal strength failure when it falls below a threshold strength. In a system that communicates with an implantable medical device,
A diversity antenna system including a plurality of antennas configured to transmit an output signal to an implantable medical device and receive an input signal from the implantable medical device;
An external system controller;
A transceiver adapted to transmit an output data frame by modulating the output signal and to receive an input data frame by demodulating the input signal;
A plurality of receiving modules each having an input and an output coupled to one antenna of the diversity antenna system, and the output of one receiving module of the plurality of receiving modules according to a reception path selection signal Including a switch circuit that connects the external system control device to the transmitter / receiver,
An antenna control circuit adapted to generate the receive path selection signal, the antenna control circuit comprising:
A signal quality evaluation circuit coupled to the transceiver and adapted to generate a quality indication of the input signal processed by each receiving module of the plurality of receiving modules;
A receive path selector coupled to the transceiver and adapted to adjust the receive path selection signal based on the quality indication of the input signal generated for the plurality of receive modules .   The signal quality evaluation circuit comprises an input frame failure detector adapted to detect an input frame failure from the input signal processed by each receiving module of the plurality of receiving modules, the receive path selector; 30. The system of claim 29, adapted to deselect a receiving module of the plurality of receiving modules when the receiving module indicates the input frame failure.   The input frame failure detector detects a cyclic redundancy check (CRC) failure from the input signal processed by each reception module of the plurality of reception modules, and when the CRC failure is detected, 32. The system of claim 30, comprising a CRC failure detector adapted to indicate the input frame failure.   The input frame failure detector detects a comma indicating a data frame from the input signal processed by each receiving module of the plurality of receiving modules during a predetermined time window, and during the predetermined time window 31. The system of claim 30, further comprising a comma missing detector adapted to indicate the response failure of each receiving module if the comma is not detected in the receiver.   30. The signal quality evaluation circuit comprises a signal strength detector adapted to measure an intensity parameter that is a measure of the intensity of the input signal processed by each receiving module of the plurality of receiving modules. System.   34. The system of claim 33, wherein the receive path selector is adapted to adjust the receive path selection signal based on the measured strength parameter of the plurality of receive modules.   The signal strength detector comprises an input signal strength fault detector adapted to detect an input signal strength fault associated with the input signal processed by each receiving module of the plurality of receiving modules; 35. The system of claim 34, wherein the selector is adapted to deselect the receiving module of the plurality of receiving modules when the input signal strength failure is indicated at the receiving module.   The antenna control circuit further comprises a path switching timing circuit coupled between the reception path selector and the switch circuit, wherein the path switching timing circuit transmits a frame of the output data frame, or 30. The system of claim 29, adapted to hold the receive path selection signal while a frame of an input data frame is being received.   The output signal and the input signal are each modulated by amplitude shift keying (ASK), and the transceiver demodulates the input signal with an ASK modulator that modulates the output signal with the output data frame. 37. The system of claim 36, comprising an ASK demodulator that recovers the input data frame. A method of operating a telemetry system that communicates with an implantable medical device comprising:
Transmitting an output signal to the implantable medical device and receiving an input signal from the implantable medical device using a diversity antenna system including a plurality of antennas, and transmitting the output signal Transmitting an output data frame by modulating the output signal, and receiving the input signal comprises receiving an input data frame by demodulating the input signal;
Selecting an antenna of the diversity antenna system to become an active antenna according to an antenna selection signal, wherein the active antenna is used for transmitting the output signal and receiving the input signal;
Generating an input signal monitoring signal based on a predetermined communication protocol;
Generating a quality indication of the input signal by detecting at least one quality measure of the input signal in response to each of the input signal monitoring signals;
Adjusting the antenna selection signal based on the quality indication of the input signal.   39. The method of claim 38, wherein transmitting the output data frame comprises transmitting a multi-frame message that each includes a plurality of data frames of the output data frame.   Generating the input signal monitoring signal includes starting counting a predetermined response time interval when reception of a response frame is expected in accordance with the predetermined communication protocol, the response frame being the input Detecting at least one quality measure of the input signal in response to one or more frames of the output data frame being one of the data frames and transmitted to the implantable medical device; 40. The method of claim 39, comprising detecting a response failure during a predetermined response time interval, wherein the response failure is a data transmission error associated with the response frame.   Detecting the response failure includes detecting the response frame during the predetermined response time interval, and the response failure is detected when the response frame is not detected during the predetermined response time interval. 41. The method of claim 40, wherein the method is detected.   Detecting the response failure includes detecting a comma indicating reception of the response frame during the predetermined response time interval, wherein the response failure is detected by the comma during the predetermined response time interval. 41. The method of claim 40, wherein the method is detected if not detected.   Detecting the response failure includes detecting a cyclic redundancy check (CRC) failure in the response frame during the predetermined response time interval, wherein the response failure is during the predetermined response time interval. 41. The method of claim 40, wherein the method is detected when the CRC failure is detected.   Furthermore, during the transmission of one of the multi-frame messages using the first antenna of the diversity antenna system selected to be the active antenna when the response frame is expected to be received Starting a predetermined non-response period, and starting counting the predetermined response time interval is expected to receive the response frame, and each one or more subsequent response frames are expected to be received. When starting the counting of the predetermined response time interval during the one transmission of the multi-frame message, wherein the one or more subsequent response frames are each of the input data One of the frames and responding to one or more of the output data frames transmitted to the implantable medical device The method of claim 40 that.   Adjusting the antenna selection signal to select a different antenna of the diversity antenna system to become an active antenna if the response fault is detected during the predetermined response time interval; 45. The method of claim 44, comprising adjusting the antenna selection signal.   Adjusting the antenna selection signal further, if the predetermined non-response period is exhausted when the input data frame is not received in the state where there is no data transmission error during the predetermined non-response period. 46. The method of claim 45, comprising adjusting the antenna selection signal to select a second antenna of the diversity antenna system to be an active antenna.   And further comprising generating an antenna test signal that causes a test frame of the output data frame to be transmitted before transmitting one of the multi-frame messages, and starting counting the predetermined response time interval. 41. The method of claim 40, comprising starting counting the predetermined response time interval after the transmission of the test frame.   Adjusting the antenna selection signal to select a different antenna of the diversity antenna system to become the active antenna when the response fault is detected during the predetermined response time interval; 48. The method of claim 47, further comprising adjusting the antenna selection signal.   Starting counting the predetermined response time interval may start counting the predetermined response time interval during one transmission of the multi-frame message if reception of the response frame is expected. 41. The method of claim 40 comprising.   Adjusting the antenna selection signal is such that if the response failure is detected during the one transmission of the multi-frame message, the antenna becomes the active antenna after the one transmission of the multi-frame message. 50. The method of claim 49, comprising adjusting the antenna selection signal to select different antennas of the diversity antenna system.   Further comprising timing a transmission period, each including a period during which a predetermined number of data frames of the output data frame are transmitted, and starting counting the predetermined response time interval comprises: 41. The method of claim 40, comprising starting counting the predetermined response time interval during each transmission period when reception is expected.   Adjusting the antenna selection signal is different antennas of the diversity antenna system to become the active antenna at the end of each transmission period if the response failure is indicated during each transmission period. 52. The method of claim 51, comprising adjusting the antenna selection signal to select.   40. The method of claim 39, wherein generating the input signal monitoring signal comprises generating a signal strength calculation signal prior to one transmission of the multi-frame message. Generating the quality indication of the input signal;
Measuring a strength parameter, each representing a strength of the input signal associated with one antenna of the diversity antenna system;
Storing the measured intensity parameter;
Each is associated with one of the intensity parameters, and each of the diversity parameters is based on the intensity parameter and a weighting factor associated with timing of measuring one of the intensity parameters in response to the signal intensity calculation signal. 54. The method of claim 53, comprising calculating a signal strength index associated with one antenna of the antenna system.   Adjusting the antenna selection signal includes adjusting the antenna selection signal to select an antenna of the diversity antenna system to be the active antenna based on the signal strength index. 55. The method of claim 54. A method of operating a telemetry system that communicates with an implantable medical device comprising:
Transmitting an output signal to the implantable medical device and receiving an input signal from the implantable medical device using a diversity antenna system including a plurality of antennas, and transmitting the output signal Transmitting an output data frame by modulating the output signal, and receiving the input signal comprises receiving an input data frame by demodulating the input signal;
Selecting an active antenna from the diversity antenna system according to an antenna selection signal;
Detecting a transmission failure allegedly related to null;
In response to detecting the transmission failure, adjusting the antenna selection signal to select a different active antenna of the diversity antenna system;
Holding the antenna selection signal while a frame of the output data frame is transmitted or a frame of the input data frame is received;
Selecting the different active antennas from the diversity antenna system in accordance with the adjusted antenna selection signal.   51. The method of claim 50, wherein selecting the active antenna comprises selecting an antenna that receives the input signal and transmits the output signal.   Detecting the transmission failure includes detecting an input frame failure from the input signal, wherein the input frame failure is a data transmission error in at least one frame of the input data frame, and the antenna selection signal 51. adjusting the antenna selection signal to select the different active antennas from the diversity antenna system when the input frame failure is indicated. the method of.   Detecting the transmission failure comprises detecting a cyclic redundancy check (CRC) failure from the input data frame and indicating the input frame failure when the CRC failure is detected. 58. The method according to 58.   Detecting the transmission failure includes detecting a comma indicating reception of the frame of the input data frame during the predetermined time window, and when the comma is not detected during the predetermined time window. 59. The method of claim 58, further comprising indicating the input frame failure.   Detecting the transmission failure includes detecting a response failure that is a data transmission error in at least one response frame of the input data frame, wherein the at least one response frame is a frame of the output data frame Adjusting the antenna selection signal in response to transmission of the antenna adjusts the antenna selection signal to select the different active antenna from the diversity antenna system when the response failure is indicated. 51. The method of claim 50, comprising:   Detecting the response failure comprises detecting at least one response frame of the input data frame during a predetermined time interval starting with transmission of the frame of the output data frame; and 62. The method of claim 61, comprising indicating the response failure if no response is detected.   Detecting the response failure includes detecting a cyclic redundancy check (CRC) failure detector in at least one response frame of the input data frame after transmission of the frame of the output data frame, wherein the CRC failure is 64. The method of claim 61, comprising indicating the response failure when detected.   Detecting the transmission fault includes detecting at least one signal strength fault of the input signal and the output signal, and adjusting the antenna selection signal is indicated when the signal strength fault is indicated. 51. The method of claim 50, comprising adjusting the antenna selection signal to select the different antennas of the diversity antenna system. Detecting the signal strength impairment comprises:
Measuring an intensity parameter that is a measure of the intensity of the input signal;
Dynamically generating a threshold intensity based on the measured intensity parameter;
65. The method of claim 64, comprising indicating the signal strength impairment when the measured strength parameter falls below the dynamically generated threshold strength. A method of operating a telemetry system that communicates with an implantable medical device comprising:
Transmitting an output signal to the implantable medical device and receiving an input signal from the implantable medical device using a diversity antenna system including a plurality of antennas, and transmitting the output signal Transmitting an output data frame by modulating the output signal, and receiving the input signal comprises receiving an input data frame by demodulating the input signal;
Processing the input signal through a plurality of processing paths, each coupled to one antenna of the diversity antenna system;
Detecting a quality indication of the input signal processed by each processing path of the plurality of processing paths;
Selecting a processing path among the plurality of processing paths based on the quality indication associated with the detected plurality of processing paths.   Detecting the quality indication includes detecting an input frame failure in each processing path of the plurality of processing paths, and selecting the processing path selects a processing path in which the input frame failure is not detected. 68. The method of claim 66, comprising:   68. The method of claim 67, wherein detecting the input frame failure comprises detecting a cyclic redundancy check (CRC) failure.   69. The method of claim 68, wherein detecting the input frame failure detects a lack of commas indicating an input data frame of the input data frame.   68. The method of claim 66, wherein detecting the quality indication comprises measuring an intensity parameter that is a measure of the intensity of the input signal processed by each processing path of the plurality of processing paths.   The method of claim 70, wherein selecting the processing path includes selecting the processing path among the plurality of processing paths based on the measured intensity parameter for the plurality of processing paths.   Measuring the strength parameter includes detecting an input signal strength fault associated with the input signal processed by each processing path of the plurality of processing paths, and selecting the processing path includes selecting the input 72. The method of claim 71, comprising selecting a processing path in which no signal strength impairment is detected.   68. Selecting the processing path includes selecting the processing path while no frame of the output data frame is transmitted and no frame of the input data frame is received. the method of.   74. The method of claim 73, further comprising modulating each of the output signal and the input signal by amplitude shift keying (ASK).

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