JP5452647B2 - Data conversion system and method - Google Patents

Description

  The present invention relates to a data conversion system and a data conversion method, and more specifically to a data conversion system and a data conversion method for performing nonlinear data conversion.

  An optocoupler is a device that communicates signals from a first device to a second device using light. Thus, optocouplers can be used to provide electrical isolation, such as between certain components or circuits. Electrical isolation can be advantageously used to prevent a component or circuit from drawing excessive current. In addition, electrical isolation can be used to prevent short circuits or other problems within the device from affecting other devices. As a result, optocouplers are often used to insulate electrical devices and / or electrical circuits.

  One isolation application is used when the device is placed in an explosive or hazardous environment. An optocoupler can be used to ensure that the device does not draw excessive current, cannot draw, and therefore cannot produce an electrical spark or cause ignition.

  Optocouplers have drawbacks. Optocouplers have a relatively slow switching speed. As a result, the optocoupler has a limited signaling bandwidth. Further, the optocoupler is a passive device and does not perform any signal transmission control or signal transmission adjustment.

In one aspect of the invention, a data conversion system that performs non-linear data conversion on a digitized AC signal comprises:
An input for receiving a digitized AC signal;
An output that outputs a non-linearly transformed signal;
A non-linearly transformed signal that is coupled to the input and output, receives the digitized AC signal, and non-linearly transforms the digitized AC signal using a predetermined transfer function to create a non-linearly transformed signal And a processing system configured to transfer to the output.

Preferably, the predetermined transfer function creates a non-linearly transformed signal with respect to a predetermined reference point.
Preferably, the predetermined transfer function is configured to alternatively compress or amplify the digital value of the digitized AC signal.

Preferably, the predetermined transfer function is configured to alternatively compress or amplify the digital value of the AC signal digitized with respect to the distance from the predetermined reference point.
Preferably, the non-linear data transformation substantially preserves phase information within the non-linear transformed signal.

Preferably, the non-linear data transformation preserves zero crossing information in the non-linear transformed signal.
Preferably, the non-linear data transformation substantially reduces the signal bandwidth of the non-linear transformed signal.

In one aspect of the present invention, a data conversion method for a digitized AC signal includes:
Receiving a digitized AC signal;
Nonlinearly transforming the digitized AC signal using a predetermined transfer function to create a nonlinearly transformed signal;
Transferring the non-linearly transformed signal.

Preferably, the predetermined transfer function creates a non-linearly transformed signal with respect to a predetermined reference point.
Preferably, the predetermined transfer function is configured to alternatively compress or amplify the digital value of the digitized AC signal.

Preferably, the predetermined transfer function is configured to alternatively compress or amplify the digital value of the AC signal digitized with respect to the distance from the predetermined reference point.
Preferably, the non-linear data transformation substantially preserves phase information within the non-linear transformed signal.

Preferably, the non-linear data transformation preserves zero crossing information in the non-linear transformed signal.
Preferably, the non-linear data transformation substantially reduces the signal bandwidth of the non-linear transformed signal.

In one aspect of the present invention, an optocoupler transmission system for controlling signal transmission via an optocoupler transmission medium comprises:
An optocoupler,
Coupled to the optocoupler, receives a transmission attempt from the first device, determines whether the second device is already transmitting via the optocoupler, and accepts the transmission attempt is a deadband after the occurrence of power up A controller configured to transmit from the first device via the optocoupler if the second device has not transmitted and the deadband period has passed, and determines whether the period is out including.

  Preferably, the controller is further configured to wait for the first device to transmit via the optocoupler when the second device is already transmitting, until the second device has finished transmitting.

  Preferably, the controller is further configured to wait for the first device to transmit through the optocoupler if the transmission attempt is within the deadband period until the deadband period has expired.

Preferably, the optocoupler transmission system includes at least two devices communicating via the optocoupler.
Preferably, the optocoupler transmission system implements a master-slave communication scheme.

In one aspect of the present invention, a transmission control method for controlling signal transmission via an optocoupler transmission medium includes:
Receiving a transmission attempt from a first device;
Determining whether the second device is already transmitting over the optocoupler transmission medium;
Determining whether receipt of a transmission attempt is outside the deadband period after the occurrence of power up;
Transmitting from the first device via an optocoupler transmission medium when the second device is not transmitting and the deadband period has elapsed.

  Preferably, the method further comprises waiting for the first device to transmit over the optocoupler transmission medium if the second device is already transmitting, until the second device has finished transmitting. .

  Preferably, the method further comprises waiting for the first device to transmit over the optocoupler transmission medium until the deadband period has elapsed if the transmission attempt is within the deadband period.

Preferably, the optocoupler transmission medium includes at least two devices communicating via the optocoupler transmission medium.
Preferably, this method implements a master-slave communication scheme.

  The same reference number represents the same element on all drawings. It should be understood that the drawings are not necessarily drawn to scale.

It is a figure which shows the bus loop system by embodiment of this invention. FIG. 5 shows further details of the isolation features of a signal processor according to an embodiment of the present invention. 1 is a diagram illustrating a conversion system that performs data conversion on a digitized AC signal in accordance with an embodiment of the present invention. FIG. It is a figure which shows the transfer function by embodiment of this invention. It is a figure which shows the AC signal in the input of a conversion system. FIG. 3 shows a digitized AC signal after non-linear data conversion according to the present invention. 3 is a flowchart illustrating a data conversion method of a digitized AC signal according to an embodiment of the present invention. 1 is a diagram illustrating a prior art optocoupler communication system that performs duplex communication between device A and device B via an optocoupler transmission medium. FIG. 1 is a diagram illustrating an optocoupler communication system according to an embodiment of the present invention. FIG. 3 shows further details of an optocoupler communication system according to an embodiment of the present invention. 3 is a flowchart illustrating a transmission control method for controlling signal transmission through an optocoupler transmission medium according to an embodiment of the present invention.

  1-11 and the following description are specific examples to teach those skilled in the art how to make and use the best mode of the invention. In order to teach the inventive principles, some conventional aspects have been simplified or omitted. Those skilled in the art will appreciate variations from these examples that fall within the scope of the invention. Those skilled in the art will appreciate that the features described below can be combined in various ways to form multiple variations of the invention. As a result, the invention is not limited to the specific examples described below, but only by the claims and their equivalents.

FIG. 1 shows a bus loop system 100 according to an embodiment of the present invention. The bus loop 100 includes a host system 1, a bus loop 4, a bus device 10, and a signal processor 30 that couples the bus device 10 to the bus loop 4. The host system 1 generates a loop voltage V _L and a loop current I _L on the bus loop 4. The host system 1 can include a central controller, CPU, or some other processing system used to process signals received on the bus loop 4. According to one embodiment of the present invention, the bus loop 4 includes a two-wire bus loop 4. However, it should be understood that the bus loop 4 need not include a two-wire bus loop.

The bus device 10 can include all forms of sensors or meters, such as a flow meter. In embodiments where the bus device 10 includes a flow meter, the flow meter may include a vibratory flow meter, such as a Coriolis flow meter or a density meter. As shown in FIG. 1, the bus device 10 includes a sensor 13 and bus device electronics 20. The bus equipment electronics 20 can include any form of CPU, processing system, or microprocessing system. According to an embodiment of the present invention, the sensor 13 is configured to generate a first analog signal and input the first analog signal to the bus equipment electronics 20. Bus instrument electronics 20 can generate a second analog signal in the form of a variable loop current I _L flowing through the bus loop 4. The bus device 10 can be configured to draw a predetermined or limited amount of power when used with the two-wire bus 4. Due to the measurement communication protocol and power limitations built into the bus loop system 100, the bus device 10 can be isolated from the two-wire bus loop 4 using the signal processor 30. In some embodiments, the signal processor 30 may include an intrinsically safe (IS) barrier (dashed line).

  The insulation limits the power that the bus device 10 can draw from the two-wire bus loop 4 and the host system 1. Insulation prevents damage to the two-wire bus loop 4 and the host system 1 in the event of a catastrophic failure of the bus device 10. Further, the insulation removes the risk of explosion and prevents ignition of all explosive or flammable materials in the environment of the bus equipment 10. S. Limit power transfer through the barrier.

  FIG. 2 shows further details of the isolation features of the signal processor 30 according to an embodiment of the invention. The signal processor is illustrated as receiving a first analog signal from the bus device 10. However, it should be understood that the first analog signal need not originate from the bus device 10 and that the signal processor 30 can be utilized in other environments where analog signal processing is required. An analog signal received from the bus device 10 via the lead 220 is received by the analog-to-digital converter 240, and this signal is digitized by the analog-to-digital converter 240. According to one embodiment of the invention, the analog-to-digital converter 240 includes a ΔΣ converter that converts the analog signal into a serial bitstream. However, it should be understood that other analog-to-digital converters can be used and the particular analog-to-digital converter used should not limit the scope of the present invention.

  According to an embodiment of the present invention, the signal processor 30 includes an optocoupler 115 connected between the two-wire bus loop 4 and the analog-to-digital converter 240. The optocoupler 115 is sometimes called an optical isolator, an optical coupler, or a photocoupler. The optocoupler 115 electrically insulates the bus device 10 from the host system 1. As a result, the bus device 10 cannot short-circuit the two-wire bus loop 4. Furthermore, a catastrophic failure of the bus device 10 cannot draw an excessive current from the host system 1. The optocoupler 115 includes a transmitter light source 122 and a receiver light source 123. Transmitter light source 122 and receiver light source 123 include all forms of laser transmitter light source and laser receiver light source, LED transmitter light source and LED receiver light source, LED laser transmitter light source and LED laser receiver light source, etc. Photoreactive electronic components can be included.

  The transmitter light source 122 and the receiver light source 123 are generally formed adjacent to each other, and the light generated by the transmitter light source 122 is received directly by the receiver light source 123. In other embodiments, transmitter light source 122 and receiver light source 123 are separated by an optical device, such as, for example, a fiber optic cable. In some embodiments, the two components are formed in a single package as shown in FIG. However, it should be understood that in other embodiments, the transmitter light source 122 and the receiver light source 123 may include separate components.

  The transmitter light source 122 generates an optically encoded signal that includes a conversion of current to emitted light. The receiver light source 123 receives this optically encoded signal and converts the received light back into an electrical signal, which is substantially identical to the original electrical signal at the transmitter light source 122. is there. Therefore, the optocoupler 115 is well suited for transferring digital signals.

  In the embodiment shown in FIG. 2, the bus device 10 generates a first analog signal that is sent to the analog-to-digital converter 240. The analog-digital converter 240 outputs a digital signal. This digital signal is received by the transmitter light source 122 and sent to the receiver light source 123. The receiver light source 123 then sends the received signal to the signal conditioner 250.

  Signal conditioner 250 can process a digital signal, which can be, for example, in the form of a serial bitstream, and can convert the digital signal to a scaled pulse width modulation (PWM) signal. Thereafter, the PWM signal can be converted into a second analog signal and output to the bus loop 4.

  FIG. 3 illustrates a conversion system 100 that performs non-linear data conversion on a digitized AC signal in accordance with an embodiment of the present invention. The conversion system 100 includes one or more inputs 101 and one or more outputs 102. Conversion system 100 receives a digitized AC signal at input 101 and outputs the converted signal at output 102. The converted signal can be converted into a more efficient and convenient form for transmission over a transmission medium, such as transmission through optocoupler 115, for example. However, other transmission media are contemplated and are within the scope of this specification and the claims.

  The conversion system 100 receives the digitized AC signal and non-linearly transforms the digitized AC signal by using a predetermined transfer function to create a converted signal portion, and the converted signal portion Can be configured to forward. The conversion system 100 can convert a digitized AC signal with respect to a predetermined reference point. The conversion system 100 can convert a digitized AC signal with respect to a distance from a predetermined reference point, such as a vertical distance (ie, voltage) from the reference point.

  Conversion system 100 can include all forms of systems, including part of signal processor 30 or other barrier device, analog-to-digital (A / D) converter, processor or microprocessor, preprocessor, and the like. Instead, in some embodiments, the conversion system 100 may include a portion of the bus device 10 or a subsystem of the bus device 10.

  The conversion system 100 can include a processing system 104 and storage (not shown). The processing system 104 can include a conversion routine 110, a digitized AC signal storage 111 (or storage of at least a portion of a digitized AC signal, such as a signal portion), and a predetermined transfer function 112. The predetermined transfer function 112 is used to process the digitized AC signal or signal portion thereof and perform a non-linear transformation of the signal portion (see discussion below).

  FIG. 4 shows a transfer function according to an embodiment of the present invention. This transfer function is non-linear, including both compression and amplification. This is shown in the legend above the graph. Further, in some embodiments, compression and amplification can also be non-linear.

  This transfer function changes the digitized AC signal, such as by adjusting a specific value or region, without changing the overall shape of the input waveform. This transfer function may include a mathematical function that converts the digitized AC signal. Alternatively, the transfer function can include a series of coefficients multiplied by a digitized AC signal, which is essentially a digital filter. The digitized AC signal is converted to improve the transfer of the digitized AC signal and to improve the efficiency of the transfer. Data conversion improves the quality of transmission by limiting bandwidth. Data conversion maintains phase information and advantageously maintains phase information while reducing bandwidth. Data conversion accomplishes this by both compression and amplification of the digitized AC signal.

  In some embodiments, digitization can include a digital communication protocol imposed on a time-varying AC signal, such as an analog measurement signal. For example, a HART digital communication protocol can be superimposed on an analog voltage signal or analog current signal. The HART protocol may use phase continuous frequency shift keying (CP-FSK) in some embodiments. However, it should be understood that other communication protocols and modulations are contemplated and are within the scope of this specification and the claims.

  The transfer function performs amplification on input values that are within a specified distance from the reference point. One reference point can be the zero crossing point even if the AC signal zero crossing is shifted above or below the zero voltage level. However, other reference points are contemplated and are within the scope of this specification and claims.

  Amplification can achieve a predetermined gain. Amplification can be substantially linear or non-linear. In some embodiments, the gain can vary with distance from the reference point. Amplification around the reference point preserves the zero crossing information. Amplification around the reference point can make zero-crossing identification easier.

  Conversely, the transfer function performs compression on signal portions that exceed a predetermined distance from a reference point, such as the zero crossing point previously described. The compression can be substantially linear or non-linear. The compression can achieve a predetermined compression. In some embodiments, the compression can vary with distance from the reference point.

  FIG. 5 shows an AC signal at the input of the conversion system 100. This AC signal includes a time-varying signal including amplitude and period. This AC signal may have already been digitized, or alternatively, in some embodiments, digitized by the conversion system 100 prior to conversion.

  FIG. 6 shows a digitized AC signal after non-linear data conversion according to the present invention. From this figure, it can be seen that the overall peak-to-peak amplitude of the AC signal is greatly reduced and compressed without changing the shape of the waveform. In this example, the original AC signal is compressed from about 250 original amplitude to about 30 amplitude. However, at the same time, the amplitude around the reference point, which is here the zero crossing point (even if the amplitude is not 0), is amplified. In the amplified region around the reference point, the digital values are about 3 units apart, as opposed to a compressed region where the digital values are about 1 unit vertically apart. This is done so that the reference points of the digitized AC signal are closer together and not difficult to distinguish, such as when the signal region around the reference point is compressed. The compressed digital value can be difficult to determine, particularly in the presence of noise superimposed on the digital value.

  The net result is that digital values away from the reference point (such as near the peak) are relatively closer in terms of vertical distance as a result of compression. Conversely, the digital values around the reference point are moved away vertically by amplification. The result is that the reference points are more distinguishable while the overall AC signal requires less overall bandwidth.

FIG. 7 is a flowchart 700 of a method for data conversion of a digitized AC signal according to an embodiment of the present invention. In step 701, a digitized AC signal is received.
In step 702, the digitized AC signal is nonlinearly transformed. A transfer function is used to compress signals away from the reference point (ie, compress large digital values). The compression can be any desired amount of compression, and any desired compression can be used. This compression of the signal portion of the voltage domain operates to reduce the bandwidth of the digitized AC signal, making the transmission of the digitized AC signal through the optocoupler more efficient. In addition, the transfer function is used to amplify a signal close to the reference point by a predetermined gain (ie, amplify a small digital value). Amplification can be by any desired amount of gain. Amplification preserves phase information, including phase information provided by the zero crossing of the digitized AC signal. In addition, amplification can help distinguish zero crossings in the digitized AC signal after the digitized AC signal has passed through the optocoupler.

  In step 703, after compressing / amplifying the signal portion, the non-linearly transformed signal is transferred to the optocoupler for transmission. After transmission, phase information including zero crossing information can be determined from the non-linearly transformed signal. Further, if desired, compression and amplification can optionally be reversed after transmission, such as by using a mirror image (ie, inverse) transfer function. The method can then loop back to step 701 and repeatedly receive and process the signal portion.

  FIG. 8 shows a conventional optocoupler communication system that performs duplex communication between device A and device B via an optocoupler transmission medium. Optocoupler transmission media include optocouplers and associated wires or other conductors. Two separate transmission paths are included, so that duplex communication (ie communication in both directions) can be performed. In some embodiments, the communication includes half-duplex communication, where only one device can transmit at a time.

  Prior art optocoupler communication systems have drawbacks. Both device A and device B can attempt to communicate at the same time. Attempting simultaneous communication in a half-duplex communication system results in transmission failures. Further, if the transmission from device A creates an echo back to device A, device A may erroneously interpret the received echo as a legitimate transmission from device B.

  FIG. 9 shows an optocoupler communication system 900 according to an embodiment of the present invention. Optocoupler communication system 900 includes a controller 920 that coordinates communication between device A 905 and device B 907 over a transmission medium including optocoupler 115. The optocoupler 115 of some embodiments performs half-duplex (or simplex) communication between devices, where only one device can transmit at a time.

  It should be understood that the controller 920 can be located anywhere within the optocoupler communication system 900, and the controller 920 is shown to the right of the optocoupler 115 for illustration only. In some embodiments, the controller 920 can include components of the signal processor 30. Further, in some embodiments, the controller 920 can include a component of device A 905 or device B 907, where the device operates like a master communication device. At the same time, the other device (s) operate as slave communication device (s).

  The optocoupler communication system 900 is configured to prevent reception of echoes. Alternatively or additionally, the optocoupler communication system 900 is configured to prevent multiple devices from transmitting at a time.

  The optocoupler communication system 900 of some embodiments receives a transmission attempt from the first device A 905, determines whether the second device B 907 is already transmitting via the optocoupler 115, and transmits the transmission attempt. It is determined whether the reception is outside the deadband period after the occurrence of power-up, and if the second device B 907 is not transmitting and the deadband period has elapsed, the first via the optocoupler 115 1 device A 905 is configured to transmit.

  FIG. 10 shows further details of an optocoupler communication system 900 according to an embodiment of the present invention. In this embodiment, controller 920 and optocoupler 115 are combined into one device. The combined device can include additional functionality and additional circuitry. The controller 920 can include switches 931 and 932 that are switched by the controller 920 to coordinate transmission through the optocoupler 115. These switches can include any form of switch.

  FIG. 11 is a flowchart 1100 of a transmission control method for controlling signal transmission through an optocoupler transmission medium according to an embodiment of the present invention. In step 1101, a transmission attempt is received from a device such as device A. The transmission attempt can be from any device, but it should be understood that device A is used in this figure and example for clarity.

  In step 1102, it is determined whether device B is already transmitting. If device B is already transmitting, the method proceeds to step 1103. If device B is not already transmitting, the method branches to step 1105.

In step 1103, device B is already transmitting, and device A waits for transmission. This standby is performed until the device B completes the transmission.
In step 1104, the method waits for another transmission attempt until the transmission from device B is complete. This transmission may include a transmission from device B to device A in some embodiments, although other devices are contemplated and are within the scope of this specification and claims.

  In step 1105, device B is not already transmitting, but the method checks to see if the attempt is outside the deadband. If the transmission attempt is not outside the deadband, the method loops back to step 1101 and all transmissions are waited until the deadband period has elapsed. Otherwise, if the transmission attempt is outside the deadband, the method proceeds to step 1106.

  For some bus equipment, during the power-up phase, the equipment may generate measurements or other data that are not included in the specification and should not be transmitted. For this reason, this method can implement a deadband period during a predetermined time after power-up. Signals received during this deadband period can be determined to be unreliable and can be ignored. Signals that arrive after the deadband expires are determined to be acceptable.

  In step 1106, device B waits for transmission. This can include additional devices where more than two devices can transmit over the optocoupler transmission medium.

  In step 1107, device A is allowed to transmit. In step 1108, the method checks to see if device A has finished transmitting. If device A has not finished transmitting, the method loops back to step 1106. When device A has finished transmitting (at that time), the method loops back to step 1101 and waits for further transmission attempts.

Claims (10)

An optocoupler transmission system (900) for controlling signal transmission through an optocoupler transmission medium, comprising:
A first device (905);
A controller (920) electrically connected to the first device (905) to enable bidirectional transmission;
A second device (907) electrically connected to the controller (920) to enable bidirectional transmission;
With
The controller (920) includes an optocoupler (115) ,
Wherein the controller (920) will receive attempts transmission (transmit attempt) from said first device (905), said second device (907) already through the optocoupler (115), said first device (905) is being transmitted towards determines whether (already transmitting MIDI) or receives attempt the transmission, it is determined whether the outside deadband period after a power-up occurrence (deadband period) (outside), the second device (907) is Orazu is transmitted, if the a dead band period elapsed already (elapsed the), allowing transmission from the through the optocoupler (115) the first device (905) Ru is configured to,
Optocoupler transmission system (900). When the second device (907) is already transmitting, the controller (920) allows the first device (905) to transmit the optocoupler (115) until the second device (907) completes transmission. 2. The optocoupler transmission system (900) of claim 1, further configured to hold off for transmission over the network. When the transmission attempt is within the deadband period, the controller (920) transmits the first device (905) via the optocoupler (115) until the deadband period has elapsed. The optocoupler transmission system (900) of claim 1, further configured to wait. The optocoupler transmission system (900) of claim 1, wherein the optocoupler transmission system (900) includes at least two devices (905, 907) communicating via the optocoupler (115). The optocoupler transmission system (900) of claim 1, wherein the optocoupler transmission system (900) implements a master-slave communication scheme. The first device (905), the controller (920) electrically connected to the first device (905) so as to be capable of bidirectional transmission, and the controller (920) can be electrically bidirectionally transmitted. A second device (907) connected to
The controller (920) is a transmission control method for controlling signal transmission through an optocoupler transmission medium in an optocoupler transmission system (900) comprising an optocoupler (115) ,
The controller (920) receiving a transmission attempt from the first device;
The controller (920) determining whether the second device is already transmitting over the optocoupler transmission medium;
The controller (920) determining whether receipt of the transmission attempt is outside a deadband period after a power-up occurrence;
The second device is Orazu is transmitted, wherein when a dead band period has already been elapsed, and a step of allowing said controller (920) is transmitted from the first device through the optocoupler transmission medium Including methods. The method further comprises waiting for the first device to transmit over the optocoupler transmission medium until the second device has completed transmission if the second device is already transmitting. 6. The method according to 6. The method further comprises waiting for the first device to transmit over the optocoupler transmission medium until the deadband period has elapsed if the transmission attempt is within the deadband period. 6. The method according to 6. The method of claim 6, wherein the optocoupler transmission medium includes at least two devices communicating via the optocoupler transmission medium. The method of claim 6, wherein the method implements a master-slave communication scheme.

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