JP2009002879A - Gps receiver - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a GPS receiver that allows rapid positioning processing when the electric wave state is good even if the power supply is marginal in a system, and can avoid a failure where the whole system shuts down by simple control processing even if the electric wave state is bad. <P>SOLUTION: This GPS receiver 100 is provided with a plurality of receiving processing circuits 16-1 to 16-n capable of independently executing the receiving processing of GPS signals, and positions the current position based on a plurality of GPS signals received by the plurality of receiving processing circuits. The GPS receiver has a controlling means 18 for decreasing the number of reception processing circuits put into an operating state among the plurality of receiving processing circuits 16-1 to 16-n based on the passage of a preset time from the start of the positioning. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a GPS receiving apparatus including a plurality of reception processing circuits that can independently execute GPS signal reception processing.

  In general, a GPS receiver includes a plurality of reception processing circuits that can independently execute GPS signal reception processing. It is possible to simultaneously receive signals from at least four GPS satellites and determine the current position based on the received data. Currently, 24 GPS satellites orbit around the earth, and normally, a GPS receiver is provided with 8 to 16 reception processing circuits.

  In recent years, a GPS receiver is sometimes mounted on a small portable electronic device. In this case, it is assumed that the GPS receiver is driven by a small battery.

Further, the following technologies are disclosed as conventional technologies related to the present invention. For example, in Patent Documents 1 and 2, only a reception channel circuit that is receiving a GPS signal used for positioning calculation is operated, and other reception channel circuits are stopped to reduce useless power consumption. Techniques for making them disclosed are disclosed. Further, in Patent Document 3, a plurality of reception channel circuits are operated when external power is supplied, and a single reception channel circuit is driven in a time-division manner when switched to battery driving, so that a plurality of GPS satellites are operated. A technique for receiving the signal is disclosed.
JP 2004-191054 A JP-A-6-88867 JP-A-6-102338

  Even if the conventional GPS receiver is a battery-powered device, the power supply has a considerable margin. However, in a system that does not have a power source such as a small battery as a driving source, the signal receiving circuit requires a relatively large driving current, so that when a plurality of signal receiving circuits are operated at the time of positioning operation, The current consumption is greatly increased and the battery voltage is greatly reduced. Further, when the operation is continued as it is, a large number of drive currents are required in inverse proportion to the decrease in the battery voltage so as to compensate for the decrease in the battery voltage, thereby causing a vicious circle in which the battery voltage further decreases. As a result, when the radio wave condition was poor and it took a long time to determine the position, the battery voltage dropped to a level below the minimum voltage of the system and the system was shut down.

  Generally, when the number of signal receiving circuits to be used increases, the current consumption increases, but the time required for positioning can be reduced. On the other hand, if the number of signal receiving circuits used is reduced, the current consumption is reduced, but the time required for positioning is increased.

  Therefore, if the number of signal receiving circuits to be operated is simply reduced from the beginning in order not to reduce the battery voltage, there arises a problem that the time required for the positioning process is uniformly extended.

  In addition, a system that measures the battery voltage at the same time as starting the GPS receiver and selects the number of signal receiving circuits to be driven based on the measured value is also conceivable. In this case, a circuit that measures the battery voltage is also conceivable. In addition, a control operation for determining an operation based on the measured value is required, and there is a problem that power consumption is increased and a circuit configuration is increased accordingly.

  The object of the present invention is to enable quick positioning processing even when the radio wave condition is good even in a system where the power source is not sufficient, and even if the radio wave condition is poor, simple control processing is possible. An object of the present invention is to provide a GPS receiver that can avoid such a problem that the entire system shuts down.

In order to achieve the above object, the invention according to claim 1
A plurality of reception processing circuits capable of independently executing GPS signal reception processing are provided, the current position is determined based on the plurality of GPS signals received by the plurality of reception processing circuits, and the driving power is In the GPS receiver supplied by
Control means is provided for reducing the number of reception processing circuits in the operating state among the plurality of reception processing circuits based on the passage of a preset time from the start of positioning.

The invention according to claim 2 is the GPS receiver according to claim 1,
A data table representing a transition of a power supply voltage when the plurality of reception processing circuits are operated at a number before reduction;
The control means includes
With reference to the data table, when the power supply voltage falls below a predetermined threshold, the number of reception processing circuits to be activated is reduced.

The invention described in claim 3 is the GPS receiver according to claim 1 or 2,
The control means includes
The reception processing circuit is deactivated by stopping the operation clocks supplied to the reception processing circuit.

  According to the present invention, even in a system where the power source is not sufficient, it is possible to perform quick positioning by operating many reception processing circuits when the radio wave condition is good, and the reception process takes time due to poor radio wave condition etc. In this case, it is possible to prevent the situation that the power supply voltage is extremely lowered by reducing the number of reception processing circuits to be operated. Furthermore, there is an effect that such an operation can be realized by a simple control process without requiring a complicated process such as measuring the power supply voltage or judging based on the measured value.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a block diagram showing an internal configuration of a GPS receiver according to an embodiment of the present invention.

  The GPS receiver 100 according to this embodiment is a system having a function of receiving a GPS signal using a small battery E1 as a drive source and measuring a current position, and an antenna 10 that receives a radio wave transmitted from a GPS satellite. A preamplifier 11 that amplifies a signal in the frequency band of the GPS signal among received radio waves, a high-frequency receiving circuit unit 12 that detects and amplifies the GPS signal from the amplified signal, and converts the signal into an intermediate frequency signal, and an intermediate frequency signal And a digital signal processing unit 13 that individually decodes signals from a plurality of GPS satellites by various signal processing and calculates position information, and a power supply circuit that receives power from the battery E1 and supplies an operating voltage to each unit And a device control circuit unit 20 that performs control processing of the entire system such as display control for a display unit (not shown) and input control from an operation input unit. There.

  The digital signal processing unit 13 is, for example, a DSP (Digital Signal Processor) in which an internal circuit is integrated and packaged on a single semiconductor chip. A multi-channel decoder 16 that individually decodes GPS signals transmitted from GPS satellites, a GPS control circuit unit 18 as control means for performing drive control of the multi-channel decoder 16 and positioning calculation based on GPS signals, and the multi-channel decoder A memory 17 for inputting / outputting data between the GPS control circuit unit 18 and the GPS control circuit unit 18, a ROM (Read Only Memory) 28 storing a control program and control data executed by the GPS control circuit unit 18, and GPS control The circuit unit 18 includes a RAM (Random Access Memory) 29 that provides a working memory space.

  The multi-channel decoder 16 includes n (for example, 8 to 16) search engines 16-1 to 16-n as reception processing circuits, and each of the search engines 16-1 to 16-n is independent of each other. It is configured to perform reception processing of signals sent from GPS satellites. Here, the reception process is a process of combining a C / A (Coarse and Acquisition code) code or a C / A code and a P code (Precision code) included in the GPS signal from the intermediate frequency signal. Large current consumption occurs. Further, the reception processing here may include navigation data decoding processing.

  The multi-channel decoder 16 is provided with a selector for individually shutting off / passing operation clocks respectively supplied to the search engines 16-1 to 16-n, and driving signals from the GPS control circuit section 18 or driving stoppage. A plurality of search engines 16-1 to 16-n can be individually operated by the signal, or the clock signal can be individually stopped to be in a non-operating state.

  Further, information on whether or not the GPS signal reception process has been started in each search engine 16-1 to 16-n and the sensitivity of the received signal is obtained via the memory 17 or directly via GPS. You may comprise so that it can recognize with the control circuit part 18. FIG.

  FIG. 2 is a data chart showing the data structure of the GPS signal, and FIG. 3 is a chart for explaining the contents of the data structure of the GPS signal.

  The GPS signal is a radio wave having a predetermined frequency obtained by performing spread spectrum modulation on a C / A code and a P code composed of predetermined 0 and 1 data strings. For the spread spectrum modulation, a different PRN (pseudo random noise) code is used for each GPS satellite, and the plurality of search engines 16-1 to 16-n individually use the PRN code assigned to each GPS satellite. By performing the composite processing, each GPS signal can be combined and processed individually without receiving interference of signals from other GPS satellites.

  Further, navigation data as shown in FIG. 2 is superimposed on the C / A code and the P code of the GPS signal, and it is possible to obtain information necessary for the compensation process of positioning from this navigation data. Yes. The navigation data is 50 bps (bit / s) data superimposed on the C / A code and the P code. As shown in FIG. 2, the data has 5 subframes per frame. Includes 10 words of data (one word is 30 bits) each including a synchronization word.

  As shown in the chart of FIG. 3, the subframe 1 includes the satellite clock correction count of the GPS satellite itself that is transmitting the signal, the data update time, and various flags. The subframes 2 and 3 contain trajectory information. For subframes 4 and 5, all the satellites transmit the same content. The contents of subframe 4 include almanac (rough orbit information) and ionization correction coefficients for all GPS satellites (up to 32 satellites) in orbit, and the contents of subframe 5 include the health of almanac and satellites. Information indicating a state or the like is included. Since the data of these subframes 4 and 5 has a large amount of data, they are divided into pages and accommodated in subframes, and all information is indicated by data of 1 to 25 pages. Therefore, in order to acquire the entire contents of the navigation data, it is necessary to receive a signal of 25 frames over 12 minutes and a half.

  The GPS receiver 100 of this embodiment does not perform positioning processing using all navigation data, but mainly performs positioning processing using C / A codes (or C / A codes and P codes). Therefore, positioning of the current position can be realized by a relatively short time reception process.

  FIG. 4 is a graph showing the contents of the battery characteristic table stored in the ROM 28.

  The above-described ROM 28 stores a battery characteristic table 28a as control data. The battery characteristic table 28a is a data table representing a time-series change in the voltage of the battery E1 when all the search engines 16-1 to 16-n of the multi-channel decoder 16 are simultaneously driven. For each short time interval, the time from the start of driving and the value of the percentage of the battery voltage are stored in association with each other.

  As shown in FIG. 4, when all the search engines 16-1 to 16-n of the multi-channel decoder 16 are driven simultaneously, the drive current is large. For example, the battery voltage is the internal resistance of the battery E1. It drops to about 70% at a stretch due to voltage effect. After that, as the battery voltage decreases, the output current needs to be further increased. Therefore, the battery voltage gradually decreases, falls below 60% after a certain time, and falls below 40% after a certain time. Show voltage change.

  Such a change in battery voltage appears uniformly from when the battery is in full capacity to when it is used to some extent. Therefore, except when the remaining capacity of the battery is small, the change in the battery voltage when all the search engines 16-1 to 16-n of the multi-channel decoder 16 are in the operating state actually measures the battery voltage. Therefore, it is possible to predict relatively accurately from the battery characteristic table 28a and the elapsed time.

  Next, the positioning operation of the current position in the GPS receiver 100 having the above configuration will be described.

  First, an outline will be described. In the GPS receiving apparatus 100, a command for positioning the current position is issued from the apparatus control circuit unit 20 to the GPS control circuit unit 18, whereby the digital signal processing unit 13 starts processing to receive a GPS signal.

  When the GPS signal reception process is started, first, a driving signal for driving all the search engines 16-1 to 16-n from the GPS control circuit unit 18 to the multi-channel decoder 16 is output. Thereby, the operation clock is supplied to all the search engines 16-1 to 16-n, and the GPS signal reception process is started. In addition, the timer is counted in the GPS control circuit unit 18 from the start of the reception process, and the current battery voltage is detected in the GPS control circuit unit 18 by referring to the data corresponding to the timer count value from the battery characteristic table 28a. The percentage of is predicted.

  Here, when the radio wave condition is good, by receiving all of the search engines 16-1 to 16-n, a predetermined number (for example, four) of GPS signals necessary for positioning can be received. This is done quickly before the battery voltage drops significantly. Then, the received GPS signal information is developed in the memory 17, and the GPS control circuit unit 18 confirms this to determine that the reception is completed. Then, the GPS control circuit unit 18 outputs drive stop signals to all the search engines 16-1 to 16-n as they are to stop the reception operation. By this drive stop signal, the supply of the operation clock to all the search engines 16-1 to 16-n is stopped, and the operation current in the search engines 16-1 to 16-n becomes almost zero. In addition, since the operating current is significantly reduced, the battery voltage then returns to nearly 100%.

  When the reception process is completed, the GPS control circuit unit 18 performs a calculation process based on the reception information of the GPS signal developed in the memory 17 to generate current position information. And this is transmitted to the apparatus control circuit part 20, and positioning operation | movement is complete | finished.

  FIG. 5 is a graph showing an example of a change in battery voltage when the number of startups of the search engine is reduced during the GPS reception process, and FIG. 6 is a graph showing GPS reception when the number of startups of the search engine is not reduced. Graphs representing changes in battery voltage during processing are shown.

  On the other hand, when the radio wave condition is poor, it takes a relatively long time to receive the GPS signal even when all the search engines 16-1 to 16-n are driven. Here, if a long time elapses while all the search engines 16-1 to 16-n are driven, the battery voltage gradually decreases as shown in FIG. There is a risk that the system will shut down below the minimum voltage to maintain (eg, 60 percent voltage).

  Therefore, the GPS control circuit unit 18 counts the timer from the start of reception and refers to the battery characteristic table 28a to predict how much the battery voltage has currently decreased. Then, as shown in FIG. 5, when it is predicted that the battery voltage has decreased to a set value (for example, 65%), the GPS control circuit unit 18 causes a predetermined number of all the search engines 16-1 to 16-n to be set. Control for stopping the drive of the search engine is performed. That is, a drive stop signal is output from the GPS control circuit unit 18 to the multi-channel decoder 16, and the operation clocks of a predetermined number of search engines are stopped.

  Here, among the search engines 16-1 to 16-n, the ones that are stopped are higher in priority of search engines that are not yet in a GPS signal reception state, and the priority of search engines that are receiving GPS signals. The search engine in a state where the GPS signal sensitivity is low is preferably set high, and the search engine high in the GPS signal sensitivity is preferably set low. In addition, a predetermined number of search engines may be stopped regardless of the reception state.

  Since the drive current is reduced by a certain width due to the stop of the predetermined number of search engines, the battery voltage greatly recovers as shown at timing T1 in FIG. It is avoided that the battery voltage decreases drastically as the shutdown is performed.

  When reception of the GPS signal is completed by the remaining search engines that have not been stopped, information on the received GPS signal is expanded in the memory 17 and the GPS control circuit unit 18 determines that reception is complete. Then, the GPS control circuit unit 18 outputs a drive stop signal to the remaining search engines to stop the receiving operation. Due to this drive stop signal, the supply of the operation clock to all the search engines 16-1 to 16-n is stopped, the operation current in the search engines 16-1 to 16-n becomes almost zero, and the timing of FIG. As shown after T2, the battery voltage returns to nearly 100%.

  Based on the reception information of the GPS signal developed in the memory 17, the GPS control circuit unit 18 performs calculation processing to generate information on the current position, which is transmitted to the device control circuit unit 20 to perform a positioning operation. Exit.

  Next, the GPS reception control process executed by the GPS control circuit unit during the positioning operation will be described in detail with reference to a flowchart.

  FIG. 7 shows a flowchart of GPS reception control processing executed by the GPS control circuit unit, and FIG. 8 shows a flowchart of timer interruption processing executed by interruption during the GPS reception control processing.

  The GPS reception control process in FIG. 7 is started when, for example, a command for a positioning process for the current position is issued from the device control circuit unit 20. When this process is started, first, various initialization processes are executed (step S1), and then a drive signal is output to the multi-channel decoder 16 to drive all the search engines 16-1 to 16-n. (Step S2). As a result, the operation clock is supplied to all the search engines 16-1 to 16-n, and all of them are in the operating state.

  Subsequently, the first flag SF indicating the stop of a predetermined number of search engines is sequentially set to “0” (step S3), the count value of the timer T is set to “0” (step S4), and the timer of FIG. Settings are made to advance the execution of the interrupt process (step S5).

  When the timer interrupt setting in step S5 is performed, the timer interrupt processing of FIG. 8 is executed in parallel at short regular intervals. That is, the timer value T is incremented by “1” every short time (step S21), and the value of the battery characteristic table 28a is read using this value as an address (step S22). Then, the table value (predicted value of the battery voltage percentage) is compared with a predetermined value (for example, 65%) or less (step S23). Note that the predetermined value here may be set to a value slightly higher than the lowest voltage of the system. As a result of the comparison, if it is not less than the predetermined value, the timer interrupt process is terminated as it is, but if it is less than the predetermined value, drive stop control of a predetermined number of search engines 16-k to 16-n is performed. (Step S24). In other words, the operation clock is stopped to make it non-operating. Further, “1” is set to the first flag SF in order to switch the control contents of the GPS reception control process (FIG. 7) (step S25), and this timer interrupt process is terminated.

  That is, the above-described timer interrupt process is repeatedly executed every short time, so that during the GPS signal reception control process, the battery characteristic table 28a is referred to and the current battery voltage is pseudo-monitored. When the value falls below a predetermined value, the predetermined number of search engines 16-k to 16-n are stopped.

  When the timer interrupt is canceled (step S5) and the process proceeds to step S6 in the GPS reception control process of FIG. 7, the first flag SF is confirmed and a discrimination process is performed (step S6). If the first flag SF is “0” (driving state of all search engines 16-1 to 16-n), the process proceeds to step S7 and GPS reception using all the search engines 16-1 to 16-n is performed. If the first flag SF is “0” (predetermined number of search engines 16-k to 16-n are in a stopped state), the process proceeds to step S8, and several search engines other than these are selected. The used GPS reception process is executed.

  Then, the data developed in the memory 17 is confirmed to determine whether the reception is completed (step S9). If the reception is not completed, the processing from step S6 is repeatedly executed. On the other hand, if it is determined in step S9 that at least four GPS signals have been received and it is determined that the reception has been completed, the process proceeds to step S10, where the current position is determined by sequentially calculating the current position (step S10). The current position information is output to the apparatus control circuit unit 20 (step S12), the progress of the timer interrupt process is prohibited (step S13), and the GPS reception control process is terminated.

  By such GPS reception control processing, as described above, at the start of reception, the reception processing using all the search engines 16-1 to 16-n can promptly receive the GPS signal. The operations of the predetermined number of search engines 16-k to 16-n are stopped, and an extreme decrease in battery voltage is avoided.

  As described above, according to the GPS receiving apparatus 100 of this embodiment, even if the system has no power supply, it operates many search engines 16-1 to 16-n when the radio wave condition is good. While quick positioning processing is possible, if the reception process takes time due to poor radio wave conditions, etc., the number of search engines 16-1 to 16-n to be operated is decreased with the passage of time. The effect that the situation where the power supply voltage is extremely reduced can be prevented. Furthermore, there is an effect that such an operation can be realized by a simple control process without providing a circuit for measuring the power supply voltage.

  Such an action is particularly useful in a wristwatch that operates using a small battery as a drive source or a system in which a GPS reception function is added to a form terminal.

  Further, by using the battery characteristic table 28a representing the transition of the battery voltage, for example, when developing a plurality of systems having different battery characteristics, a battery characteristic table is created by obtaining the battery voltage transition data, and this is stored in the ROM. The development cost can be reduced because it is only necessary to write the data in the program.

  Further, when the search engines 16-k to 16-n are stopped, the supply of the operation clock is only stopped, so that the drive current can be reliably stopped by simple control.

  The present invention is not limited to the above-described embodiment, and various modifications can be made.

  FIG. 9 is a block diagram showing an example of a change in the internal configuration of the GPS receiver, FIG. 10 is a flowchart showing a modified example of the timer interrupt process, and FIG. 11 is a diagram of the search engine during the GPS reception process. The graph showing an example of the change of the battery voltage at the time of reducing the starting number in the beginning is shown.

  For example, as shown in FIG. 9, the battery characteristic table 28a is not stored in the internal memory of the digital signal processing unit 13, but is stored in an external ROM 28B or the like and can be read into the GPS control circuit unit 18. It is also good. With such a configuration, when the battery E1 is changed, the battery characteristic table 28a can be easily changed correspondingly.

  In the above embodiment, battery voltage data corresponding to the timer value T is read using the battery characteristic table 28a, and the timing for stopping a predetermined number of search engines is measured based on the data value of the battery voltage. However, since the elapsed time when the data value of the battery voltage is equal to or less than the predetermined value is known, the elapsed time T exceeds the set time (Tth) without referring to the battery characteristic table 28a as shown in FIG. The predetermined number of search engines may be stopped (steps S32 and S24).

  With such a configuration, it is not necessary to prepare a battery characteristic table or to read out a data value every short time only by setting a time for stopping a predetermined number of search engines in advance.

  In the above embodiment, a predetermined number of search engines are stopped in one stage as time passes. However, the number of search engines that are driven in a plurality of stages may be reduced to the beginning. . For example, as shown in FIG. 11, by reducing the number of search engines that are driven at the timing of T11 to T16, the battery voltage can be changed with less rapid fluctuations.

  In addition, how to reduce the number of search engines to be driven may be performed by a hardware configuration such as a sequencer, not by the program operation of the control means, or by a power supply voltage cut-off, etc. without stopping the clock. May be in a non-operating state. In addition, the details shown in the embodiments can be appropriately changed without departing from the spirit of the invention.

It is a block diagram which shows the internal structure of the GPS receiver of embodiment of this invention. It is a data chart which shows the data structure of a GPS signal. 3 is a chart for explaining the contents of the data configuration of FIG. 2. It is the figure which showed the contents of the battery characteristic table stored in ROM as a graph. It is the graph which showed an example of the change of the battery voltage during GPS reception processing. It is the graph which showed the change of the battery voltage during the GPS reception process when not reducing the starting number of search engines. It is a flowchart which shows the process sequence of the GPS reception control process performed by a GPS control circuit part. It is a flowchart which shows the process sequence of the timer interruption process performed by interruption during the GPS reception control process of FIG. It is a block diagram which shows the example of a change of the internal structure of a GPS receiver. It is a flowchart which shows the modification of a timer interruption process. It is the graph which showed the change of the battery voltage at the time of reducing the starting number of search engines in the beginning during GPS reception processing.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Antenna 11 Preamplifier 12 High frequency receiving circuit part 13 Digital signal processing part 15 Power supply circuit part 16 Multichannel decoder 16-1 to 16-n Search engine (reception processing circuit)
18 GPS control circuit section 28 ROM
28a Battery characteristics table (data table)
100 GPS receiver E1 battery

Claims (3)

A plurality of reception processing circuits capable of independently executing GPS signal reception processing are provided, the current position is determined based on the plurality of GPS signals received by the plurality of reception processing circuits, and the driving power is In the GPS receiver supplied by
A GPS receiving apparatus, comprising: control means for decreasing the number of reception processing circuits to be in an operating state among the plurality of reception processing circuits based on elapse of a preset time from the start of positioning. A data table representing a transition of a power supply voltage when the plurality of reception processing circuits are operated at a number before reduction;
The control means includes
2. The GPS reception according to claim 1, wherein the number of reception processing circuits which are set in an operation state when the time when the power supply voltage falls below a predetermined threshold with reference to the data table is reduced. apparatus. The control means includes
3. The GPS receiver according to claim 1, wherein the reception processing circuit is brought into a non-operating state by stopping operation clocks supplied to the reception processing circuit. 4.

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