WO2007010689A1

WO2007010689A1 - Clock generation device, on-vehicle device, and clock generation method

Info

Publication number: WO2007010689A1
Application number: PCT/JP2006/312133
Authority: WO
Inventors: Shinjiro Kato
Original assignee: Pioneer Corporation
Priority date: 2005-07-22
Filing date: 2006-06-16
Publication date: 2007-01-25

Abstract

An on-vehicle device (100) includes a GPS signal reception unit (101), an oscillation unit (102), a GPS satellite quantity detection unit (103), a correction unit (104), a clock generation unit (105), and a music composition reproduction unit (106). According to a detection result in the GPS satellite quantity detection unit (103), the clock generation unit (105) frequency-converts the GPS signal received by the GPS signal reception unit (101) and corrected by the correction unit (104) or the oscillation signal outputted from the oscillation unit (102) and outputs it as a clock to the music composition reproduction unit (106).

Description

Specification

Clock generating device, in-vehicle device, and clock generating method

Technical field

TECHNICAL FIELD [0001] The present invention relates to a clock generation device, an in-vehicle device, and a clock generation method using a GPS (Global Positioning System) signal. However, the use of the present invention is not limited to the above-described clock generation device, in-vehicle device, and clock generation method.

Background art

Conventionally, audio devices have been equipped with ceramic oscillators or crystal oscillators. Clocks are generated using oscillation signals output from these oscillators, and software such as music data is generated in accordance with the generated clocks. Data is reproduced (for example, see Patent Document 1 below).

[0003] Ceramic oscillators and crystal oscillators such as those listed in Patent Document 1 affect the phase and frequency of output oscillation signals due to changes in temperature when the environment changes. (Signal cycle fluctuation) becomes large. Therefore, it is desirable to use an oscillator having a temperature compensation function for an audio function unit incorporated in an in-vehicle navigation device.

[0004] In addition, the navigation function incorporated in the above-described navigation device generates an oscillation signal force with the highest level of accuracy output from an atomic clock to receive a GPS signal and perform positioning. A high-accuracy oscillation signal that can be matched with a GPS signal is required, and a high-performance oscillator such as a temperature compensated crystal oscillator (hereinafter referred to as “TCXO”) is installed.

Patent Document 1: Japanese Patent Laid-Open No. 05-343992

Disclosure of the invention

Problems to be solved by the invention

However, in an in-vehicle audio apparatus, an oscillator having a minimum necessary accuracy is used as a clock used for an operation capable of reproducing music and the like, so that sound quality can be improved. An example is the problem of not being able to. Also has temperature compensation function Although the oscillator outputs an oscillation signal with high accuracy and low jitter, it is more expensive than a normal oscillator and has not been used in an audio apparatus.

[0007] On the other hand, the conventional navigation device has a function of generating a highly accurate oscillation signal by TCXO and a function of receiving a GPS signal generated with the highest level of oscillation signal force. Is used only for positioning processing of the navigation function unit, and there is a problem that it is not used effectively by other function units (for example, audio function unit).

Means for solving the problem

[0008] In order to solve the above-mentioned problems and achieve the object, a clock generation device according to the invention of claim 1 includes a GPS signal receiving means for receiving GPS signals of a plurality of GPS satellites, and an oscillation signal. Oscillating means for outputting, GPS satellite number detecting means for detecting the force transmitted from the number of GPS satellites received by the GPS signal receiving means, and the waveform of the GPS signal using the oscillation signal A correction unit that corrects the frequency of the GPS signal and the oscillation signal to generate a clock according to the number of GPS satellites detected by the GPS satellite number detection unit. And a clock supply means for supplying the clock generated by the clock generation means to an external device driven by using the clock.

[0009] Further, the in-vehicle apparatus according to the invention of claim 4 includes a GPS signal receiving means for receiving GPS signals of a plurality of GPS satellites, an oscillating means for outputting an oscillation signal, and the GPS signal receiving means. GPS satellite number detection means for detecting how many GPS satellites received by the GPS signal, correction means for correcting the GPS signal using the oscillation signal, and GPS satellite number detection means According to the number of detected GPS satellites, a clock generating means for generating a clock by frequency-converting either one of the corrected GPS signal or the oscillation signal, and generating the clock by the clock generating means. And a music playback means for playing back music using the clock supplied with the clock power S.

[0010] In addition, a clock generation method according to the invention of claim 6 is provided for each of a plurality of GPS satellites. The GPS signal is received from the GPS signal receiving step, the GPS signal received by the GPS signal receiving step is detected from the number of GPS satellites detected by the number of GPS satellites, and output from the oscillation means. A correction process for correcting the waveform of the GPS signal using an oscillation signal, and either the corrected GPS signal or the oscillation signal according to the number of GPS satellites detected by the GPS satellite number detection process. A clock generation step of generating a clock by frequency-converting two signals, and a clock supply step of supplying the clock generated by the clock generation step to an external device driven using the clock. Features.

Brief Description of Drawings

FIG. 1 is a block diagram showing an example of a functional configuration of an in-vehicle device according to an embodiment of the present invention.

[FIG. 2] FIG. 2 is a flowchart showing an example of a processing procedure of the in-vehicle device which is effective in this embodiment.

FIG. 3 is a block diagram of an example of a hardware configuration of the in-vehicle device according to the first embodiment.

FIG. 4 is a block diagram illustrating a configuration example of a clock generation unit.

[Fig. 5-1] Fig. 5-1 is an explanatory diagram showing frequency shift due to C / A code matching

[Fig. 5-2] Fig. 5-2 is an explanatory diagram showing time lag due to C / A code matching.

FIG. 6 is an explanatory diagram showing the principle of positioning using GPS signals.

FIG. 7 is a flowchart showing a procedure of clock generation processing in the clock generation unit.

FIG. 8 is a block diagram of an example of a hardware configuration of the in-vehicle device according to the second embodiment.

FIG. 9 is a block diagram illustrating a configuration example of a clock generation unit.

FIG. 10 is a block diagram showing another configuration example of the clock generation unit.

FIG. 11 is a flowchart showing a procedure of clock generation processing in the clock generation unit. Explanation of symbols

[0012] 100 in-vehicle device

101 GPS signal receiver

102 Oscillator

103 GPS satellite number detector

104 Correction section

105 Clock generation

106 Music playback section

BEST MODE FOR CARRYING OUT THE INVENTION

[0013] Exemplary embodiments of a clock generation device, a vehicle-mounted device, and a clock generation method that are useful for the present invention will be described below in detail with reference to the accompanying drawings.

[0014] (Embodiment)

First, a functional configuration of an in-vehicle device that is focused on the embodiment of the present invention will be described. FIG. 1 is a block diagram showing an example of a functional configuration of an in-vehicle device that is effective in the embodiment of the present invention. The in-vehicle device 100 includes a GPS signal receiving unit 101, an oscillating unit 102, a GPS satellite number detecting unit 103, a correcting unit 104, a clock generating unit 105, and a music reproducing unit 106.

[0015] The GPS signal is generated using a highly accurate oscillation signal output from an atomic oscillator provided in a GPS satellite as a transmission wave. The oscillation signal that composes this GPS signal is jitter (signal period) with higher frequency accuracy than the clock used in the audio machine, even if the frequency shift due to the Doppler effect caused by the high-speed movement of GPS satellites is taken into account. It is excellent as a clock with less fluctuation.

[0016] Therefore, in the present embodiment, the oscillation signal output from the TCXO necessary for supplying the GPS signal to the navigation function unit or the GPS signal itself, which is the high-precision oscillation signal power output from the atomic oscillator, is used. It is configured to be supplied as a clock source for the audio function unit.

[0017] The GPS signal receiving unit 101 includes a GPS signal receiver, and receives a GPS signal transmitted from a GPS satellite orbiting a satellite orbit about 20000 km above the ground. Always in orbit More than 24 GPS satellites are in operation. The GPS signal receiving unit 101 receives a receivable GPS signal among the GPS signals transmitted from the plurality of GPS satellites, and outputs them to the GPS satellite number detecting unit 103 and the correcting unit 104.

The oscillation unit 102 generates an oscillation signal that repeats a sine wave having a predetermined frequency or a square wave. The generated oscillation signal is output to the correction unit 104 and the clock generation unit 105. As an element that generates an oscillation signal, a crystal oscillator, a ceramic oscillator, or the like is generally used. However, in this embodiment, since the GPS signal received by the GPS signal receiving unit 101 is corrected, a high precision such as TCXO is used. It is desirable to use an oscillator that outputs the oscillation signal.

[0019] The number of GPS satellites detection unit 103 detects how many GPS satellites are received from the GPS signal input from the GPS signal reception unit 101, and the detection result is a clock generation unit. Output to 105.

The correction unit 104 corrects the GPS signal input from the GPS signal reception unit 101 using the oscillation signal input from the oscillation unit 102. A GPS signal transmitted from a GPS satellite has a waveform frequency or phase deviation due to passage through the ionosphere until it is received by the receiver (in this embodiment, the GPS signal receiving unit 101). Arise. Therefore, the correction unit 104 corrects the deviation of the GPS signal using the oscillation signal input from the oscillation unit 102 and outputs the corrected GPS signal to the clock generation unit 105.

[0021] The clock generation unit 105 receives a GPS signal from the correction unit 104 and an oscillation signal from the oscillation unit 102, and generates a clock by frequency-converting one of these two signals. . The determination of whether to use the GPS signal or the oscillation signal to generate the clock is made based on the detection information of the number of GPS satellites input from the GPS satellite number detection unit 103.

[0022] When performing three-dimensional positioning using a GPS signal, the correction unit 104 cannot obtain a completely accurate GPS signal unless it receives GPS signals from four or more GPS satellites. Therefore, as an example of determining whether the clock generation unit 105 uses a GPS signal or an oscillation signal to generate a clock, four GPS satellites are detected from the detection result input from the GPS satellite number detection unit 103. If this is the case, there is a method of generating a clock using GPS signals. [0023] Further, as another example of the determination in the clock generation unit 105, a function unit that newly determines the reception state of the clock is provided, and even if the GPS signal is received from less than four GPS satellites, the reception state is If the clock is more stable than the oscillating signal, use a GPS signal to generate the clock.

The music playback unit 106 plays back music data based on the clock input from the clock generation unit 105. The music playback unit 106 includes recording means for storing music data. The music playback section 106 may read the music data by recording means. Alternatively, the music playback section 106 may be connected to an external recording means for storing music data to read music data to be played back sequentially. May be.

[0025] When a clock supply unit that supplies a clock to an external device that is driven using a clock is provided instead of the music playback unit 106, the use of the clock generated by the clock generation unit 105 is not limited. It can be used without In this case, the clock generator according to the present invention is configured.

[0026] (Processing procedure of in-vehicle device)

Next, a processing procedure of the in-vehicle device that works on this embodiment will be described. FIG. 2 is a flowchart showing an example of the processing procedure of the in-vehicle device that works on this embodiment. In the flowchart of FIG. 2, first, the GPS signal receiving unit 101 determines whether or not a GPS signal has been received (step S201). If the GPS signal is received and received (step S201: Yes), the correction unit 104 uses the received GPS signal as the oscillation signal output from the oscillation unit 102. (Step S202) ₀

[0027] In addition to performing the process of step S202, the GPS satellite number detection unit 103 determines whether or not the GPS satellites received by the GPS signal reception unit 101 have transmitted from GPS satellites having a GPS signal strength or higher (step S203). When the GPS signal is transmitted from four or more GPS satellites (step S203: Yes), the clock generation unit 105 subsequently generates a clock by converting the frequency of the GPS signal corrected by the correction unit 104 ( Step S204).

[0028] When the GPS signal is transmitted from less than four GPS satellites in step S203 (step S203: No), the clock generator 105 outputs the oscillation signal output from the oscillator 102. The clock is generated by frequency conversion (step S205). Finally, the song In the playback unit 106, the music data is played back using the clock generated in step S204 or step S205 (step S206), and the series of processing ends.

[0029] As described above, the in-vehicle device 100 that is effective in the present embodiment is capable of generating a high-quality clock using the GPS signal and the oscillation signal used for navigation without providing a new oscillator. S can.

[0030] Since the quality of the clock can be reproduced more faithfully, the sound quality can be improved. Further, since it is not necessary to provide a new oscillator, the audio function unit can be reduced in size and cost can be reduced.

Example 1

[0031] (Hardware configuration)

Next, a hardware configuration of the in-vehicle device according to Embodiment 1 of the present invention will be described. FIG. 3 is a block diagram of an example of a hardware configuration of the in-vehicle device according to the first embodiment. The in-vehicle device 300 includes a GPS antenna unit 310, a GPS signal processing unit 320, and an audio unit 330.

[0032] The GPS antenna unit 310 includes a GPS antenna 311 and an RF amplifier (Radio Frequency a

11 ^^ 1 "; High-frequency amplifier) 312. The GPS antenna 311 receives the GPS signal transmitted from the GPS satellite force. The RF amplifier 312 receives the GPS signal received by the GPS antenna 311. The GPS signal amplified by the RF amplifier 312 is output to the GPS signal processing unit 320.

[0033] The GPS signal processor B320 includes preamplifiers 321 and 327, finoletas 322, 323, and 324, an oscillation circuit 325, a TCX0326, an RF circuit B340, and a clock generator B350. Further, the RF circuit section 340 includes preamplifiers 341, 343, 344, and 348, a mixer 342, a voltage controlled oscillator (hereinafter referred to as “VC0”) 345, a phase comparator 346, It consists of a peripheral (1ZN) 347.

[0034] In particular, the VC circuit 345, the phase comparator 346, the frequency divider (1 / N) 347, the filter 324, and the oscillation circuit 325 in the RF circuit section 340 constitute a PLL (Phase Locked Loop) circuit. ing. VC0345 outputs an oscillation signal having a frequency corresponding to the voltage value of the input signal. The phase comparator 346 outputs a signal corresponding to the phase difference between the two input signals. Divider (1 / N) 347 outputs the input signal with a frequency of 1 / N. The PLL circuit composed of the above elements compares the phase difference between two signals input to the phase comparator 346 and outputs a signal synchronized with one of the signals (reference signal) from the VC0345. It has a function.

[0035] In the case of the GPS signal processing unit 320, the oscillation signal input from the TCX0326 is amplified by the preamplifier 348, and then divided by the frequency divider (1 / N) 347 to a frequency of 1ZN to be used as a reference signal. Comparator 346 Input. At the same time, the signal output from VC0345 is input as a feedback signal.

First, the GPS signal output from the GPS antenna unit 310 is input to the preamplifier 321. The preamplifier 321 amplifies the input GPS signal from the GPS antenna unit 310 and outputs a filter 322. The flyer 322 is a high-frequency filter, and transmits only the signal in the set high-frequency band among the GPS signals input from the preamplifier 321 and outputs the RF circuit unit 340.

The RF circuit unit 340 amplifies the GPS signal input from the filter 322 by the preamplifier 341 and then outputs the amplified signal to the mixer 342. The mixer 342 adds the GPS signal input from the preamplifier 341 and the oscillation signal input from the VC0345, and outputs a mixed GPS signal. The GPS signal output from the mixer 342 is output to the preamplifier 343. After removing noise by the filter 323, the GPS signal is amplified again by the preamplifier 344, and the GPS signal is subjected to high frequency amplification and output to the clock generator 350. .

[0038] The TCX0326 is a crystal oscillator having a function of compensating for a change in the output temperature, and outputs an oscillation signal to the RF circuit unit 340 and the clock generation unit 350 (via the preamplifier 327). The oscillation signal output from the TCX0326 is input to the RF circuit unit 340, and the frequency of the GPS signal received by the GPS antenna unit 310 is used by the clock generation unit 350 for correcting the GPS signal and generating the clock.

[0039] The clock generation unit 350 receives an RF circuit unit 340 force GPS signal, and receives an oscillation signal from the TCX0326. Of the signals input to the clock generator 350, the GPS signal is the power that received the GPS signal transmitted from the number of GPS satellites. Measures the current position of device 300 and The result is output to the GPS signal navigation unit (not shown). The positioning using the GPS signal in the clock generator 350 will be described in detail later.

[0040] In addition, the clock generation unit 350 generates a clock using either the GPS signal input from the FR circuit unit 340, or the oscillation signal input from the TCX03 26, and generates the generated clock. Output to the audio unit 330. At this time, which of the GPS signal and the oscillation signal is used depends on how many GPS satellites the GPS signal received by the GPS antenna unit 310 is transmitted from the GPS signal input from the FR circuit unit 340. The GPS signal is judged and based on the judgment result. The configuration of the clock generation unit 350 will be described in detail later with reference to the drawings.

[0041] The audio section 330 includes an audio PLL (Phase Locked Loop) 331, an audio microcomputer 332, an audio medium 333, an audio demodulation circuit 334, a D / A converter 335, an amplifier 336, and a speaker 337. It consists of les.

The audio PLL 331 generates a demodulated signal for demodulating music data on the basis of the clock input to the clock generation unit 350 of the GPS signal processing unit 320 and outputs the demodulated signal to the audio demodulation circuit 334. The audio microcomputer 332 outputs to the audio demodulation circuit 334 a control signal for controlling the music data demodulation processing using the demodulated signal input from the audio PLL 331.

The audio media 333 is a drive for reading music data recorded on a CD or DVD, and outputs the read music data to the audio demodulation circuit 334. The music data may also be recorded on a storage medium such as a hard disk or flash memory using a compression method such as MP3 or AAC.

The audio demodulation circuit 334 demodulates the music data read from the audio media 333 based on the demodulated signal input from the audio PLL 331 according to the control signal input from the audio microcomputer 332, and performs D / A Output to converter 335. The DZA converter 335 converts the demodulated music data (hereinafter referred to as “music signal”) input from the audio demodulation circuit 334 from a digital signal to an analog signal and outputs the analog signal to the amplifier 336.

The amplifier 336 amplifies the music signal input from the DZA converter 335, and Output to 337. The speaker 337 reproduces the music signal input from the amplifier 336 as sound.

[0046] In the in-vehicle device 300 configured as described above, the clock generation device according to the present invention is mounted as the clock generation unit 350, thereby supplying a high-quality clock to the audio unit 330 of the in-vehicle device 300. The sound quality of the music output from the audio unit 330 is improved. Next, the clock generator 350 will be described in detail with reference to the drawings.

FIG. 4 is a block diagram illustrating a configuration example of the clock generation unit. As shown in FIG. 4, the clock generation unit 350 includes a satellite number detection unit 351, a C / A matching unit 352, a CZA code list unit 353, a positioning unit 54, an internal clock unit 55, and a switch unit 56. Power is composed.

[0048] Based on the GPS signal input from the RF circuit unit 340, the number-of-satellite detection unit 351 determines how many GPS satellites received GPS signals, that is, how many GPS signals are received. Judgment is made, and the judgment result is output to the switch unit 356. At the same time, the input GPS signal is output from the satellite number detection unit 351 to the C / A matching unit 352 as it is.

[0049] The C / A code list unit 353 stores a pattern of a C / A code (Coarse / Acquisition code) that is a pseudo-random code different for each GPS satellite. The C / A matching unit 352 reads the C / A code of each GPS satellite from the C / A code list unit 353, and generates a matching signal using the C / A code according to the oscillation signal input from the preamplifier 327. . The generated matching signal is compared with the GPS signal input from the satellite number detection unit 351, and matching processing is performed.

[0050] Here, GPS signal matching and C / A code will be described. Currently, there are multiple GPS satellites that orbit the Earth, and each GPS satellite transmits multiple types of signals for general and military use. Among them, the signal used for commercially available navigation is the GPS signal by C / A code. The C / A code is transmitted with a 1023 bit length 1 and 0 random sequence repeated in 1.01 milliseconds. The random bit string of the C / A code is different for each GPS satellite. The in-vehicle device 300 performs matching between the matching signal generated from the CZA code stored in the CZA code list unit 353 and the received GPS signal. If the random bit strings by the C / A code match, the process of determining the frequency shift and time shift (phase difference) between the matching matching signal and the GPS signal is performed. Do it.

[0051] FIG. 5-1 is an explanatory diagram showing a frequency shift due to C / A code matching. Fig. 5-2 is an explanatory diagram showing the time lag due to C / A code matching. The square wave 510 shown in the upper part of Fig. 5-1 represents the matching signal generated from the CZA code of the GPS satellite stored in the C / A code list section 353. A square wave 511 shown in the lower part represents a GPS signal input from the satellite number detection unit 351 (here, a GPS signal transmitted from GPS satellite A as an example). A period T indicated by an arrow in the square wave 511 represents a pattern having a length of 1023 bits. Therefore, the GPS signal from GPS satellite A has a frequency shift of Δf compared to the matching signal generated from the C / A code.

In FIG. 5-2, a square wave 510 shown in the upper part represents a matching signal generated from the C / A code of GPS satellite A stored in the C / A code list section 353. The square wave 521 shown at the bottom represents the received GPS signal. The horizontal axis represents the elapsed time t with 0 as a reference. The square wave 510 and the square wave 521 have a time difference of At.

[0053] As described with reference to FIGS. 5-1 and 5-2, the matching signal generated from the C / A code stored in the C / A code list unit 353, the GPS signal actually received, For example, when the in-vehicle device 300 receives a GPS signal transmitted from GPS satellite A, there is a correspondence relationship between the frequency deviation and the time (phase) deviation. If they match, the GPS satellite A force transmitted GPS signal has been correctly received. The C / A matching unit 352 determines whether or not the correspondence between the frequency shift and the time (phase) shift matches the plurality of GPS signals input from the satellite number detection unit 351. Yes. The GPS signal for which the coincidence determination has been made is corrected for frequency and phase deviations using the oscillation signal, and is output to the positioning unit 354.

However, when the C / A matching unit 352 generates the code of the GPS signal transmitted from each GPS satellite from the C / A code stored in the CZA code list unit 353, the The oscillator provided in the device 300 is used. Therefore, the GPS signal is calculated from the difference in accuracy between the atomic oscillator installed in each GPS satellite and the oscillator installed in the in-vehicle device 300. Are not completely synchronized, resulting in a common error in the GPS signal from each GPS satellite.

FIG. 6 is an explanatory diagram showing the principle of positioning using a GPS signal. In order to perform three-dimensional positioning using GPS signals transmitted from GPS satellites, it is possible to accurately determine the current position by receiving GPS signals from three GPS satellites. However, as explained earlier, there is an error due to the difference in accuracy between the oscillators of the GPS satellite and the in-vehicle device 300, and the time (reception time) until the GPS signal transmitted from each GPS satellite is received is the actual time. Because it is detected with a value different from time, accurate positioning can be performed. In other words, if the GPS signal reception time shifts in satellites 1 to 3 as shown in Fig. 6, a difference in distance of T will occur, from satellite 1 to satellite 3 to `` desired position P ''. The distance is pseudorange 1 to pseudorange 3 considering the error of T minutes.

Therefore, in order to derive the “desired position P” at which the pseudo distance 1 to the pseudo distance 3 intersect, a GPS signal transmitted from another GPS satellite is required. Here, another GPS satellite is called GPS satellite 4. Accurate 3D positioning is achieved by combining four GPS signals derived from GPS signals from four GPS satellites. Specifically, the position of the in-vehicle device 300 is obtained using the following equations (1) to (4).

[0057] [Equation 1]

X! -x) ² + (, y! -V j ² + (z! -z) ² -S

(x ₂ -x) ² + (y ₂ -y) ² + (z ₂ -z) ² -s

x ₃ -x) ² + (y ₃ -y) ² + (z ₃ -z) 2 -s

[0058] The variables used in the equations (1) to (4) will be described below. Among the variables, T for obtaining x, y, z and S is an unknown number, and therefore the exact position of the in-vehicle device 300 can be obtained by simultaneous equations (1) to (4).

:, R, r, r: GPS satellites: 4 pseudoranges

1 2 3 4

xi, yi, zi (i = l, 2, 3, 4): GPS satellites: coordinate values representing the positions of! ~ 4 X, y, z: Coordinate values representing the position of the in-vehicle device 300

The variable S is obtained as follows.

S = TC

S: Difference in distance due to time lag of oscillator of in-vehicle device 300

T: Time difference of the oscillator of the in-vehicle device 300

C: speed of light

[0059] Therefore, when GPS signals from two GPS satellites are used, the positioning is considered as having a constant altitude and no oscillator deviation of the in-vehicle device 300. When GPS signals from GPS satellites are used, positioning is performed assuming that the altitude is constant. In order to perform accurate 3D positioning in consideration of errors, GPS signals from four or more GPS satellites must be received.

Returning to FIG. 4, the description of the clock generation unit 350 is continued. The CZA matching unit 352 receives the GPS signal input from the satellite number detection unit 351 and the C / A read from the C / A code list unit 353. Matching with the matching signal generated from the code is performed, and the matching result is output to the positioning unit 354. At the same time, a GPS signal is output to the switch unit 356.

[0061] The positioning unit 354 calculates the position information of the in-vehicle device 300 using the GPS signal matching result input from the C / A matching unit 352. The calculated position information is output to the navigation unit in accordance with the clock input from the internal clock unit 355.

Switch unit 356 outputs any one of the oscillation signal input from preamplifier 327 and the GPS signal input from C / A matching unit 352 to internal clock unit 355. The determination of which signal to output at this time is made based on the determination result of the number of GPS satellites received from the satellite number detection unit 351 and the number of GPS satellites received.

[0063] As described with reference to FIG. 6, when performing accurate three-dimensional positioning, since GPS signals from four or more GPS satellites are required, the switch unit 356 has four or more GPS signals. If received, the GPS signal input from the C / A matching unit 352 is output to the internal clock unit 355. Otherwise, the oscillation signal input from preamplifier 327 is Output to 355.

[0064] Internal clock unit 355 converts the frequency of the GPS signal or oscillation signal input from switch unit 356 to generate a clock having a predetermined frequency, and outputs the clock to positioning unit 354 and audio unit 330.

[0065] (Processing procedure of clock generation unit)

Next, the processing flow of the clock generation unit 350 will be described using a flowchart. FIG. 7 is a flowchart illustrating a procedure of clock generation processing in the clock generation unit. In the flowchart of FIG. 7, first, the satellite number detection unit 351 determines whether or not the number of GPS satellites that have received GPS signals is four or more (step S701). If the number of GPS satellites is four or more (step S701: Yes), the internal clock unit 355 generates a clock using the GPS signal (step S702).

[0066] If the GPS satellite power is less than ¾ in step S701 (step S701: No), the internal clock unit 355 generates a clock using the oscillation signal (step S703), and the series of processes is completed. To do. The clock generated by the clock generation unit 350 is output to the audio unit 330 and used for reproduction of music data.

As described above, the first embodiment uses the GPS signal or the temperature-compensated crystal oscillator force used for GPS signal processing to output any of the high-precision oscillation signals that are output. Regardless of the configuration, an in-vehicle device that uses GPS signals can generate a high-quality clock without installing a new oscillator. In the case of the in-vehicle device 300, by supplying a high-quality clock to the audio unit 330, the accuracy of music data demodulation processing in the audio demodulation circuit 334 is improved. Therefore, the sound quality of the sound output from the speaker 337 can be improved.

Example 2

[0068] (Hardware configuration)

Next, a hardware configuration of the in-vehicle device according to Embodiment 2 of the present invention will be described. FIG. 8 is a block diagram of an example of a hardware configuration of the in-vehicle device according to the second embodiment. The in-vehicle device 800 includes a GPS antenna unit 310, a GPS signal processing unit 320, an audio unit 330, and a clock switching unit 810. In-vehicle device 800 is an example A clock generator having a configuration different from 1 is used as the clock generator 820 (830) and the clock switcher 810. The configuration other than the clock generation unit 820 (830) and the clock switching unit 810 in the GPS signal processing unit 320 is the same as that of the first embodiment shown in FIG. A description thereof will be omitted.

[0069] In the case of the in-vehicle device 300 described in the first embodiment, the GPS signal satellite that receives the GPS signal has several GPS power satellites that change from ¾ or less to 4 or more, or conversely, the GPS signal satellite that receives the GPS signal. When the number of signals changes from 4 or more to 3 or less, the signal used for clock generation is switched, resulting in a phase difference in the clock. Therefore, it was necessary to set appropriate PLL circuit constants so that the audio PLL 331 would not malfunction due to the phase difference of the clock.

[0070] The second embodiment is a configuration example when the first purpose is to generate a high-quality clock as compared with the first embodiment, regardless of the positioning accuracy by the GPS signal. Therefore, if you pay attention to reception problems such as multipaths that receive the same GPS signal with multiple path forces, even if you receive a GPS signal from one GPS satellite, it will be clocked using the GPS signal. Can be generated.

In the second embodiment, the clock generation unit 820 (830) uses a clock generated using the GPS signal (hereinafter referred to as “clock 1”) and a clock generated using the oscillation signal (hereinafter referred to as “clock 2”). And a signal for discriminating the reception state of the GPS signal (hereinafter referred to as “discrimination signal”) are output to the clock switching unit 810. A detailed configuration of the clock generation unit 820 (830) will be described later with reference to FIGS.

The clock switching unit 810 is configured with the switch 811 and the system microcomputer 812.

The switch 811 receives clock 1 and clock 2 from the clock generation unit 820 (830). In addition, a control signal is input to the switch 811 from the audio microcomputer 332 of the audio unit 330, and one of the clocks 1 and 2 is output to the audio unit 330 according to the control signal.

[0073] The system microcomputer 812 receives a determination signal for determining the reception state of the GPS signal from the clock generation unit 820 (830), and receives a reproduction signal of music data from the audio microcomputer 332 of the audio unit 330 . The playback signal is currently stored in the audio unit 330 with ease. This signal represents information indicating whether the song data is being reproduced or whether the reproduction of a certain piece of music data is completed and the next piece of music data is reproduced (hereinafter referred to as “between songs”). The system microcomputer 812 outputs a control signal to the audio microcomputer 332 of the audio unit 330 based on the determination signal and the reproduction signal.

FIG. 9 is a block diagram illustrating a configuration example of the clock generation unit. The clock generation unit 820 shown in FIG. 9 includes a reception state determination unit 821, a satellite number detection unit 822, a CZA matching unit (period & time difference) 823, a C / A code list unit 824, a positioning unit 825, It consists of an internal clock unit 826 and a switch unit 827.

The reception state determination unit 821 determines the reception state of the GPS signal input from the RF circuit unit 340 and outputs the determination result to the clock switching unit 810 as a determination signal. The satellite number detection unit 822 determines how many GPS satellites the GPS signal is received based on the GPS signal input from the RF circuit unit 340, and outputs the detection result to the switch unit 827. At the same time, the input GPS signal is output from the satellite number detection unit 822 to the C / A matching unit 823 as it is.

[0076] The C / A matching unit (cycle & time difference) 823 first uses the oscillation signal input from the preamplifier 327 to generate a matching signal from the C / A code read from the C / A code list unit 824. . The C / A code list part 824 stores the C / A code of each GPS signal. Next, matching processing is performed on the generated matching signal and the GPS signal input from the satellite number detection unit 822, and the difference between the cycle and time, that is, explained in Fig. 5-1 and Fig. 5-2. By detecting and matching the frequency shift and phase shift, the GPS signal is corrected using the oscillation signal. The corrected GPS signal is output to the positioning unit 825 and the clock switching unit 810.

The positioning unit 825 performs a process for positioning the current position using the GPS signal input from the C / A matching unit (cycle & time difference) 823. The specific processing procedure is the same as the processing using the equations (1) to (4) described in the positioning unit 354 (see FIG. 4) in the first embodiment. The position information calculated by the positioning unit 825 is output to the navigation unit in accordance with the clock input from the internal clock unit 826.

The internal clock unit 826 converts the frequency of the signal input from the switch unit 827 and clocks it. And output to the positioning unit 825. The switch unit 827 outputs either the oscillation signal input from the preamplifier 327 or the GPS signal input from the C / A matching unit (cycle & time difference) 823 to the internal clock unit 826. At this time, which signal is output is determined based on the detection result input from the satellite number detection unit 822.

FIG. 10 is a block diagram illustrating another configuration example of the clock generation unit. The clock generation unit 830 shown in FIG. 10 has a configuration in which a C / A matching unit (period) 828 is added to the clock generation unit 820 shown in FIG. The C / A matching unit (cycle) 828 generates a matching signal from the C / A code read from the C / A code list unit 824 using the oscillation signal input from the preamplifier 327 force.

Next, processing when the clock generation units 820 and 830 having the configuration described with reference to FIGS. 9 and 10 are used will be described.

[0081] (Processing procedure of clock generator)

FIG. 11 is a flowchart illustrating a procedure of clock generation processing in the clock generation unit. In the flowchart of FIG. 11, first, the satellite number detection unit 822 determines whether the number of GPS satellites that have received a GPS signal is four or more (step S1101). If the number of GPS satellites is ¾ or more (step S1101: Yes), the internal clock unit 826 generates a clock using the GPS signal (step S1102). If the GPS satellite power is less than ¾ at step S 1101 (step S 1101: No), the internal clock unit 826 generates a clock using the oscillation signal (step S 1103).

At the same time as the processing of step S1101, the number-of-satellite detection unit 822 determines whether or not the number is less than the number of GPS satellites that received the GPS signal (step S1104). If the number of GPS satellites received is 1 or less (step S1104: Yes), then whether or not the GPS signal reception status is stable based on the discrimination signal output from the reception status discrimination unit 821 Is determined (step S1105).

[0083] If the reception state is stable (step S1105: Yes), whether or not the audio unit 330 is currently between songs is determined from the playback signal of the music data input from the audio unit 330. Judgment is made (step S1106). If the audio unit 330 is currently between songs (step S1106: Yes), a clock is generated using the oscillation signal (step S1107). [0084] In step S1104, when the number of GPS satellites that received the GPS signal is two or more (step S1104: No), and in step S1105, the reception state is not stable (step S1105: No). In step S 1106, if the audio unit 330 is not in the current song (step S 1106: No), a clock is generated using all GPS signals (step S 1108).

As described above, in the second embodiment, the clock generation units 820 and 830 always generate two clocks, and the generated clocks are input to the switch 8 11 of the clock switching unit 810, so that the system One of the clocks is output to the audio PLL 331 in response to a control signal from the audio microcomputer 332 of the audio unit 330 linked to the microcomputer 812.

[0086] As described above, according to the second embodiment, if a GPS signal is received from one or more GPS satellites, the opportunity to generate a clock by the GPS signal increases. In addition, assuming that the clock generated by GPS signal power is used with priority, the clock switching unit 810 can control the clock switching to reduce the frequency of switching to the clock. Therefore, it can be used without considering problems such as phase differences due to clock switching.

As described above, the in-vehicle devices 300 and 800 according to the first and second embodiments generate a high-quality clock using the GPS signal and the oscillation signal used for navigation without providing a new oscillator. That power S.

[0088] As another configuration example of the first and second embodiments, the generated clock may be replaced with a device that can carry the audio unit 330 and the navigation unit of the in-vehicle devices 300 and 800. ,. By making such a replacement, not only the vehicle but also a mobile object can be carried, and when combined with a personal navigation device, it can be compared with a conventional portable audio device without preparing a high-performance oscillator. High quality and sound quality can be provided.

Note that the clock generation method described in the present embodiment can be realized by executing a prepared program on a computer such as a personal computer or a workstation. This program is recorded on a computer-readable recording medium such as a hard disk, flexible disk, CD-ROM, M0, DVD, It is executed by being read from the recording medium by a computer. Further, this program may be a transmission medium that can be distributed through a network such as the Internet.

Claims

The scope of the claims

[1] GPS signal receiving means for receiving the GPS signals of each of a plurality of GPS satellites;

An oscillation means for outputting an oscillation signal;

GPS satellite number detecting means for detecting the force transmitted from the number of GPS satellites by the GPS signal received by the GPS signal receiving means;

Correction means for correcting the waveform of the GPS signal using the oscillation signal, and either the corrected GPS signal or the oscillation signal according to the number of GPS satellites detected by the GPS satellite number detection means A clock generation means for generating a clock by frequency-converting one signal;

Clock supply means for supplying the clock generated by the clock generation means to an external device driven using the clock;

A clock generation device comprising:

[2] The clock generation means may generate the clock by frequency-converting the GPS signal when the number of GPS satellites detected by the GPS satellite number detection means is four or more. The clock generator according to 1.

[3] The clock generation means, when receiving a GPS signal from one or more GPS satellites by the GPS signal reception means, a first clock obtained by frequency-converting the GPS signal corrected by the correction means And a second clock obtained by frequency-converting the oscillation signal,

A reception state determination unit that determines a reception state of the GPS signal received by the GPS signal reception unit and outputs a determination signal indicating a degree of stability of the reception state of the GPS signal;

A clock switching means is provided at a subsequent stage of the clock generation means,

The clock switching means, based on the determination signal output from the reception state determination means, outputs a clock having a stable output among the first clock and the second clock generated by the clock generation means. The clock generation device according to claim 1, wherein the clock generation device outputs to a supply means.

[4] GPS signal receiving means for receiving each GPS signal of a plurality of GPS satellites; An oscillation means for outputting an oscillation signal;

Correction means for correcting the GPS signal using the oscillation signal;

Clock generation means for generating a clock by frequency-converting one of the corrected GPS signal or the oscillation signal according to the number of GPS satellites detected by the GPS satellite number detection means;

Music reproduction means that is supplied with the clock generated by the clock generation means and performs music reproduction using the clock;

A vehicle-mounted device comprising:

[5] The clock generation means outputs a first clock generated using the GPS signal and a second clock generated using the oscillation signal, and the two clocks play the music If the first clock is generated and input to the clock switching means for switching the clock to be supplied to the means, the clock switching means may 5. The on-vehicle device according to claim 4, wherein the clock is switched so that the first clock is output with priority.

[6] A GPS signal receiving process for receiving each GPS signal of a plurality of GPS satellites;

A GPS satellite number detecting step for detecting the force transmitted from the number of GPS satellites by the GPS signal received by the GPS signal receiving step;

A correction step of correcting the waveform of the GPS signal using the oscillation signal output from the oscillation means;

A clock generation step of generating a clock by frequency-converting one of the corrected GPS signal or the oscillation signal according to the number of GPS satellites detected by the GPS satellite number detection step;

A clock supply step of supplying the clock generated by the clock generation step to an external device driven using the clock;

Including a clock generation method.