KR19990067119A - Earth positioning system receiver and telecommunication device combination - Google Patents

Abstract

The present invention relates to a GPS receiver 52, a communication receiver 22 or a transceiver 22, which shares a processor 26 of a communication receiver, in order to process a normal communication call volume and determine the location of a second station SS. , 46). In order to reduce the acquisition time and the current consumed by the second station SS, the first station PS of the communication system is provided with a minimum number of orbits transmitted by the orbiting GPS satellites SAT1, SAT2, SAT3 and SAT4. A GPS receiver 14 and a digital baseband processor 15 for recovering astronomical force data are mounted, the astronomical force data being downloaded to a second station SS and ready for use when position determination is required ( 32).

Description

Earth positioning system receiver and telecommunication device combination

The English abstract of Japanese Patent Laid-Open No. 07075162 discloses a promotion apparatus for use in a retail store, in which a transmitter transmits unidirectional promotional information along with position information. The subscriber processing second station, which is equipped with a receiver, a GPS receiver, a CD-ROM and an LCD panel, all connected to one processor, can receive the promotion information and send the retailer's location to the GPS receiver. As determined by it, the mapping information contained in the CD-ROM can be used to display along with the route from the subscriber's current location to the retailer.

In a known second station, each receiver performs its own function and provides the result to the processor. This is not significantly effective in terms of battery current savings.

For a suitable measurement to be made by the GPS receiver, i.e. the measurement of the arrival time of the signal from at least four GPS satellites, the GPS receiver must be able to see the sky without disturbing, for a period of approximately 10 seconds. Once the measurements have been made, the calculation of the subscriber's location needs to be processed and the results with the second station need to be displayed by any means, usually by an LCD screen. The time taken for this calculation depends on the processing power of the microprocessor of the GPS receiver. For example, an 8051 type processor requires approximately 5 seconds to perform the required processing.

Currently, the hardware required for a GPS receiver typically consists of two integrated circuits, an analog rf front end and a digital baseband processor, with a small number of discrete components. The antenna is typically a simple patch antenna that is approximately 2-3 cm in each side (carrier frequency is approximately 1.5 GHz). Typical current GPS chip sets can consume 500 to 800 mW of power at 3 volts. There are many reasons for this high power consumption, but the main reason would be that for most current applications, continuous operation is required for the new positioning created every moment. This leads to the need for a power hungry 16-bit microprocessor that is typically clocked at 25 MHz.

From the time the GPS receiver is turned on, the time it takes to generate the position determination depends on the following coefficients.

1. The time it takes to acquire a signal from enough (at least four) GPS satellites.

2. The time it takes to download enough data from the captured satellites to characterize their orbit and clock mismatch.

3. Time taken to process and calculate positions for raw measurements.

The last of these (coefficient) is easiest to describe because it contains an appropriately well defined set of calculations and thus depends on the processing power of the receiver's microprocessor. As mentioned above, this leads to an appropriate and straightforward power versus speed compromise. Current GPS chip sets use processors that are powerful enough to handle these steps in less than a second, but if the computation is done on fewer processors, it can take as little as 10 seconds.

The first two coefficients (times) are virtually completely different, since they are usually not of significant importance in a GPS receiver. This is because they should only be performed at the start and then sometimes as a background task. Capturing at least four satellites depends heavily on how much previous knowledge the system has. If you don't have any information at all, the acquisition may take an hour, while if you know the location (in tens of kilometers) and the current time (in seconds), the acquisition will take only a few seconds. At the extreme, a receiver that knows the place and time very accurately can pick up the signal almost instantaneously. Most current GPS receivers store some unprocessed satellite orbital parameters (enough to predict for weeks of cycles) in nonvolatile memory and maintain a real-time clock when they are turned off. As a result, they can capture satellites within 10 to 30 seconds that are typically turned on.

Downloading the appropriate orbital data from the satellite takes theoretically at least 30 seconds. This is because data is repeatedly transmitted in five subframes, each of which takes 6 seconds to transmit. Of course, in practice, the GPS receiver can pick up the signal at any point during the transmission period, and in certain cases, can "waste" almost the entire 6-second subframe, trying to find a recognizable preamble. Again, some current GPS receivers store this data while turned off. However, these data only have a useful life of a few hours (the orbits of the satellites are not constant), so storing them for more than one day is not very good.

The present invention relates to a combination of a GPS system and a communication transmitter or receiver. A particular but not exclusive application of the present invention is a combination of a GPS receiver and an answer-back pager. However, the pager may include a unidirectional (or receive only) pager, a cellular / wireless telephone or a mobile / portable transceiver.

In this specification, the term GPS is to be understood to include other satellite navigation systems and the US Global Positioning System. Furthermore, in the present specification, the term "ephemeris data" has been used to describe all data transmitted by GPS satellites, which characterizes the nature of the satellite orbits and of its internal clock characteristics. Describe.

1 illustrates an embodiment of the invention in which a second station comprises a GPS receiver and a response pager.

It is an object of the present invention to save the power consumption of a second station for receiving and processing GPS signals.

According to one aspect of the invention,

A first station having a GPS receiver and processor for receiving and deriving at least astronomical force data from a received GPS signal, and a first station having at least one transmitter for transmitting communication signals and astronomical data;

A GPS receiver, a communication receiver for receiving communication signals and astronomical force data from the at least one transmitter, and the GPS receiver and the to determine a location of a second station from the astronomical data and GPS signals received by the GPS receiver. A combination of a paging system and a GPS system is provided, including a second station having a processor connected to a communication receiver.

By the transmitter of the first station, which sometimes broadcasts GPS astronomical force data, the time taken to perform GPS positioning is also significantly reduced by this time, resulting in significant current savings.

According to a second aspect of the invention, there is provided a second station for use in a system for broadcasting astronomical force data relating to a GPS satellite orbiting a first station, the second station being a GPS receiver. A communication receiver for receiving communication signals and astronomical force data from the at least one transmitter, and the GPS receiver and the GPS receiver for determining a location of a second station using the astronomical data and GPS signals received by the GPS receiver. A processor connected to the communication receiver.

If desired, the clock signal generated for the processor may be used to provide an accurate time signal to the GPS receiver and its digital baseband processor. The more accurately the GPS receiver knows the time, the easier it is for the GPS receiver to capture the signal from the GPS satellites from the perspective of predicting the expected position in the sky, thus making the determination of the Doppler shift.

If desired, a modified controlled oscillator used by the processor may be used to describe the nature of the local oscillator of the GPS receiver in advance. This, in turn, reduces the degree of uncertainty when attempting to capture a signal from a GPS satellite.

If desired, the second station may include a transmitter for transmitting position data to the first station. In emergency situations, the transmitter transmits location data in a relatively low bit rate signal, allowing the signal to be detected over a larger area than is possible with higher bit rate transmissions. Can be used as Optionally, the second station may comprise coding means by which the user indicates a form of emergency and / or a coded signal indicating what services are needed at the same time as transmitting the location data. You can send

The invention is now described by way of example with reference to the drawings.

The infrastructure includes a paging system controller (PSC) 10 connected to one of the plurality of first stations PS by ground lines. The first station includes a transceiver 12 controlled by the PSC 10. GPS receiver 14 with antenna 16 connected to the input has a digital base comprising storage means (not shown) for astronomical data recovered from orbiting GPS satellites SAT1, SAT2, SAT3 and SAT4. An output connected to the band processor 15.

The paging signal and the astronomical force data from the PSC 10 are transmitted by the transceiver 12 via the antenna 18.

The second station SS comprises an antenna 20 connected to the receiver stage 22, with the output of the receiver stage 22 being supplied to the decoder 24. The processor 26 is connected to the decoder 24 via bidirectional links 27 and 28. The processor 26 operates according to the software contained in the program storage device 30. RAM 32 for storing data messages and astronomical data received from the first station PS is connected to the processor 26. The processor has an output connected to the LCD driver 34, which in turn is connected to the LCD panel 36. Keypad 38 is connected to the processor to provide a human / machine interface. The acoustic transducer 40 and the light emitter 42, such as the LED, are connected to a processor 26 which uses them as an alarm device, and in addition the light emitter 42 has messages and position data stored in the RAM 32. Can be used, for example, to deliver to a printer or personal computer (not shown). The receiver 22 is operated by the processor 26 according to the battery saving protocol, and the battery saving stage 44 is connected between the processor 26 and the receiver 22. The low-power transmitter 46 is connected between the output of the processor 26 and the antenna 20.

The patch antenna 50 is connected to a GPS receiver 52 that provides an output 54 to the processor 26, which is configured to receive received satellite data and RAM (in order to calculate the position of the second station). Use astronomical data stored in 32).

Processor 26 includes a clock circuit based on temperature controlled crystal oscillator (TCXO) 56. The TCXO 56 provides an output 58 to the GPS receiver 52, which output 58 is used within the receiver 52 to describe in advance the nature of the receiver's local oscillator. This eliminates uncertainty when attempting to capture signals from GPS satellites SAT1, SAT2, SAT3 and SAT4.

In operation, the PSC 10 causes the paging signal to be transmitted in accordance with any suitable protocol, such as known as CCIR radio paging code NO.1, otherwise POCSAG. The message received and decoded by the second stage is stored in RAM 32 for later recall and display.

Each GPS satellite (typically 24 at any time in operation) broadcasts approximately 500 bits of data enumerating its orbit and information about its internal clock, collectively referred to herein as astronomical data. This information is updated mainly every hour, but is considered valid for four hours. Thus, astronomical data only need to be relayed rarely, which can be done in a quiet period. However, the advantage of a second station for storing astronomical data in RAM 32 is significant, since positioning is likely to be within 15 to 20 seconds, of which only the first 10 seconds of active GPS is active. Include specific hardware (the remaining time is purely needed for position calculation by processor 26).

For transmission of the astronomical force data to be recognized by the second station, the astronomical force data is transmitted as a message preceded by an address code word recognizable by a second station having a GPS receiver.

In addition, the communication portion of the second station SS provides a means for supporting the GPS receiver in a number of ways.

The TCXO 56 provides an accurate (in fraction of a second) time signal. The more accurately the GPS receiver knows the time, the easier it is for the GPS receiver to capture the signal from the GPS satellites (predicting the expected position in the sky, thus making it easier to determine the Doppler shift).

The offset of the local oscillator can be characterized in advance by reference to the apparent frequency of the paging signal. This again eliminates uncertainty when attempting to capture a signal from a GPS satellite.

So-called "differential GPS" signals can be accommodated in the pager system. This is a structure that includes a fixed base station (eg, the transmitter side of the first station) that measures obvious inaccuracies in the GPS signal (caused by atmospheric effects and the US military's planned attempts to degrade the quality of the information). . Details of these inaccuracies can be sent to the GPS receiver in the field and used to improve the accuracy of proper location calculations. This results in inaccuracies better than 5 meters (not usually 100 meters).

Transmitter 46 provides a second station with bidirectional capabilities. In its simplest form, the second station SS can operate as an emergency beacon, transmitting position data as a relatively low bit rate signal, perhaps as a spread spectrum signal. In addition, the processor 26 may include coding means (not shown), which, depending on the operation of the keys of the keypad 38, cause the transmitter to send an alarm together with the form and / or position data of the emergency. Enables the transmission of coded signals that indicate service is needed.

By reading the disclosure of the present invention, other variations will be apparent to those skilled in the art. Such modifications include other features that are already known in the design, manufacture, and use of GPS and telecommunication systems and their components, and that can be used in place of or in addition to the features already described herein. While the claims are formulated herein for specific combinations of features, the disclosure scope of this specification is any feature disclosed herein, either implicitly or directly, or any new combination of such features, or any generalization thereof. It should be understood that, including whether or not related to the same invention presently claimed in any claim, and whether or not alleviate some or all of the same technical problems with the present invention. As such, Applicant discloses that, during the execution of this specification or any further specification derived therefrom, new claims may be formulated for such features and / or combinations of such features.

Claims (6)

In the combination of paging system and earth positioning system (GPS) system, A first station having a GPS receiver and processor for receiving and deriving at least ephemeris data from the received GPS signal, and at least one transmitter for transmitting the communication signal and the astronomical data; A second station having a GPS receiver, a communication receiver for receiving communication signals and astronomical force data from said at least one transmitter, and a processor, said processor using said astronomical force data and GPS signals received by said GPS receiver And a second station, connected to the GPS receiver and the communication receiver, to determine a location of a second station. A second station for use in a system for broadcasting astronomical force data relating to a GPS satellite orbiting a first station, A GPS receiver, a communication receiver for receiving communication signals and astronomical force data from a first station, and the GPS receiver for determining the position of the second station using the astronomical data and GPS signals received by the GPS receiver. And a processor coupled to the telecommunication receiver; and a second station for use in a system for broadcasting astronomical data. 3. The processor of claim 2, wherein the processor comprises a clock signal generator for generating a clock signal, And the clock signal is supplied to the GPS receiver for use in a system for broadcasting astronomical data. 4. A crystal controlled oscillator is used for generating the clock signal, The second station for use in a system for broadcasting astronomical data, characterized in that the output of the modified controlled oscillator is used in advance to describe the nature of the local oscillator of the GPS receiver. 5. A system according to any one of claims 2 to 4, comprising a transmitter connected to the processor, the transmitter being used to transmit positional data. 2 stations. 6. The processor of claim 5, wherein the processor comprises coding means, wherein the coding means allows a user to send a coded signal providing additional information at the same time as transmitting the position data. A second station for use in a system for broadcasting astronomical data.