JPH0271184A - Device for measuring gps location - Google Patents

Abstract

PURPOSE:To obtain accuracy equal to or higher than that of an atomic oscillator without using the atomic oscillator by a method wherein color subcarrier signals of television broadcasting are received at two points approximately at the same time and used as reference oscillation signals. CONSTITUTION:A reference signal generator A consisting of an antenna 7 for receiving television broadcasting and a tuner 8 and a signal converter 9 which reproduces reference signals and converts is provided. At receiving points A, B, color subcarrier signals of television broadcast signals are received by the antenna 7 approximately at the same time, amplified and band-limited by the tuner 8, and then output to the signal converter 9 as video signals. The converter 9 extracts color carrier signals from the input video signals and reproduces continuous signals synchronizing said signals, while the reproduced subcarrier signals are converted into required frequency to be used as reference signals for a device for measuring locations.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention receives equipment information and time information composed of a plurality of artificial satellites at one point or two or more points, and determines the position of the receiving point and known points. This relates to a satellite-based positioning device that determines the distance from a point to a receiving point.

[Conventional technology]

As a positioning system that uses artificial satellites, there is GPS (Global Pos.
(For GPS, see document USP 4,667.203).

When the system is completed, there will be 18 in total, 3 in each of the 6 orbits.
satellites are scheduled to be launched.

Each satellite generates signals from its built-in highly stable atomic clock.
．． 5G) Iz band (L, band) and 1.2GHz band (L.

It orbits the Earth while constantly transmitting navigation signals.

Satellite orbit information, clock information, ionospheric information, etc. necessary for positioning are transmitted by the L1 band and Lt band navigation signals.

[Explanation of principle]

With this GPS, anytime, anywhere on the earth,
It is designed to be able to receive four or more of these satellites, and a positioning device placed anywhere on the ground receives and reproduces the navigation signals transmitted by these satellites. The position of the receiving point can be determined by precisely measuring the arrival time of the radio waves to the point.

Now, calculate the true distance between the first satellite (i-1 to 18) and the receiving point, and calculate the pseudo distance (the distance obtained by multiplying the arrival time of the measured radio wave by the speed of light). , ′, the following relational expression holds.

Di ' - Di + C (Δ1.-Δtsv) where
D,' = (t++ tr )xcDr = ((
Xst xo)” + (yi; yo)”+
(z si −z o) 2 ] 1/2ΔLu
: Offset amount (error) of the clock in the positioning device to the GPS time ΔLr, v : Offset amount (error) of the clock in the satellite to the GPS time t, : Time ty when the navigation signal of the GPS satellite is received by the positioning device : GPS satellite Time C when the navigation signal was transmitted: Speed of light (Xsi, ysi, Zst): 1st cp
The position where the s-satellite issued the navigation signal (Xo+yo+Zo): Represents the position of the receiving point (where the positioning device is located).

In the equation (1) above, the position where the satellite transmitted radio waves (
X sit y sit Z si + I =L2+
...'', 18) is a known quantity that can be calculated from the orbital information and time information transmitted from the satellite as mentioned above, so the unknown quantity is the position of the receiving point (Xo+o+Zo) and t=
There are four: Δ1゜-ΔL, 2ヰ.

Therefore, by simultaneously receiving four satellites, creating four observation equations corresponding to equation (1), and solving these four observation equations using the least squares method, the position of the reception point (Xo , yo+zo) can be obtained.

A positioning device using GPS is used not only for positioning to precisely know the position of a receiving point (for example, knowing the position as a navigation device), but also for positioning to precisely know the distance between two receiving points. Moreover, the latter positioning requires the highest accuracy than the former positioning.

Let's consider the latter for a moment.

GPS positioning devices used in the field of precision surveying use the phase of the 1.5 GHz band signal and C/A for pseudorange measurement.
code, P code clock phase (1,023MHz
, and the phase of 10.23 MHz) to improve accuracy.

When the relationship corresponding to equation (1) is expressed using the phase of the signal, it is as follows.

Dr (t) = C(Δt+tx(t)−Δtsvt(
t)tr tT) +(-(φR(t)-φ1 (1)) 10,)λ ・・・・・・(2) Here, Ll: Delay time of radio waves due to the ionosphere L7: Delay of radio waves due to the troposphere Time Δt sv= (t): Delay time (offset time) of the internal clock of the satellite relative to GPS time Δt, 1x(t): Delay time (offset time) of the internal clock of the receiving device relative to GPS time nl: Certain integer λ: Measured radio wave Wavelength φ1 (tl Phase of received radio wave at receiving antenna φL(t): Phase of local signal in the positioning device (phase of reference signal generator) C: Represents the speed of light, respectively.

The delay time of the satellite internal clock with respect to the GPS time in the above formula (2), (Δtsv+(t)) and the GP of the positioning device internal clock
The delay time for time S, (ΔL++x(L)) is 1
By simultaneously receiving 2 satellites at 2 points A and B and subtracting them using the observation method, we can create an observation equation by simultaneously receiving 2 satellites called stationery at 2 points A and B. By subtracting them, we can establish an observation equation that removes these errors.

Therefore, similar to equation (1) above, by creating observation equations for the unknowns included in these equations and solving them using the least squares method, we can calculate the distances from several points to the receiving points, and the distances between the receiving points. etc. can be obtained.

For information on the principles, positioning techniques, and methods of positioning using GPS, see, for example, the Geodetic Society of Japan (rGPS - Precision Positioning System Using Artificial Satellites), Japan Surveying Association,
Details are disclosed in the November 1986 issue.

Now, if we consider the case where one satellite S■ is observed simultaneously at two points A and B at time 1, the equation (2) above becomes as follows.

D Al (++)=C(ΔLeA(++)−Δts
v+(++)LIA-tTA) +(-[φ1a(++)-φtA(++))+n,)
λ = AI + (-(φ*A(++)-φLA(tI))
++1)λ・・・・・・(3)D
Bl (++)=c (ΔLr5(++)−Δt s
v I(++)test□) +(-[φ□(L,)-φti(++)]++2)
λ −B++((φ1ll(++)−φtm(++))+n
2) λ・・・・・・(4
)(3)-(4), D Al (++)-D ++ (++) = A +
-B ++(-(φ+u(++)-φRR(tl))
= (φLA(++)−φLn(++))+ n +
n z ) λ ・・・・・・
(5) However, l A + = C(Δt, 1A(tI)−Δtsv+(
++)tlA tTA) B, =C(Δtin(++)−Δtsv+(++)
Ll-to) are shown respectively.

Furthermore, considering the i-th satellite in the same manner, the following relational expression is obtained.

Dh=-Dm=　(tt　)=A,-B.

+(-(φ*A (ti)-φ, lIl (Ll))-
(φLA(tI)−φt++(tl)+n is z
n = or 3) λ ...... (6) (i
= 1.2. ..., 18) When having multiple reception channels and receiving multiple satellites at the same time, t1-t2=tx...=mu.

Then, φLA (++) − φ1++ (1+) = φLA (tz) − φLll (L2) = φL^ (
)−φLll (L8)=α (constant)
(7) where α: indicates the fixed phase difference between the A and B reference signal generators.

becomes.

Therefore, by subtracting the plurality of observation equations in equation (6), an observation equation can be obtained in which the fixed phase difference of the reference signal generators in both side devices is eliminated. However, in a positioning device that uses a directional antenna and switches reception with a single channel reception circuit, if the receiving satellite changes, it is not possible to receive at the same time, and it is necessary to shift the measurement time and receive reception. becomes. Therefore, the value of 1 in equation (6) will be a different reception time each time the satellite changes, and will be as follows.

t,≠t2≠t,...≠t1 The phases of the reference signal generators of the positioning devices at points A and B2 at time t1 are as follows.

φLA (Ll) = φLa (t++ΔL) = φLA
(tI) + (2π/λ) (σ7.×Δt XC)・・・・・・(
8) φva(ti)=φtm(t++ΔL)=φLs
(++) +(2π/λ)(σ, ×Δt XCI・・・・・・(9
) Here Δt=ti-tl (i=”l12+3・
...) σ, A: Frequency stability of the reference signal generator in positioning device A σy: Frequency stability of the reference signal generator in positioning device B λ: Wavelength of observation radio wave C: Speed of light, respectively.

Therefore, the phase difference between the two is φLa(tt) −φLm (mui)=φLA(
CI) −φLm(tt)+(2π/λ)((σyA
−σym) ×Δ txc)x(10) =φLA(tt)−φu+(tt) 1ε・・・・・・(
10) However, ε=(2π/λ)((σyA−σy8)
×ΔtXc).

Therefore, σyA≠σ, from ε≠0 φLA (tt)−φ□ (Ll) ≠φt, A (tz)−φtm(tz)≠φL＾ (L
3) −φLII (t3)≠φLA (tt) −φ
tm (t direct) ≠ α (constant)...
...(11), and the term related to the phase of the reference signal generator in the observation equation cannot be eliminated.

It is fine if ε in equation (10) is a negligibly small value, but if the influence of the frequency stability of both reference signal generators A and B accumulates over observation time and exceeds the allowable error, the positioning accuracy will deteriorate. It causes

[Problem to be solved by the invention]

As mentioned in the above principle explanation, this type of positioning device (1
In channel switching reception systems, ultra-highly stable atomic oscillators such as rubidium and cesium are usually used as reference signal generators to minimize this effect and make ε negligible. It has become expensive.

In addition, this type of atomic oscillator belongs to special precision equipment, and is capable of vibration,
It has the disadvantage of being weak against shock and difficult to handle.

Therefore, as a user positioning device, it is desirable to provide a device that does not use an expensive atomic oscillator and can obtain the same or higher accuracy.

The present invention takes the above points into consideration and proposes a positioning device that does not use an atomic oscillator and can obtain accuracy comparable to or even higher than when using an atomic oscillator.

[Means to solve the problem]

In order to achieve this object, the device of the present invention is provided with a reference signal generator composed of an antenna for receiving television broadcast signals, a tuner, and a signal converter for reproducing and converting the reference signal, and two reception points A and B are provided. The color subcarrier signals of the same television broadcast signal are received at almost the same time, reproduced and converted by this reference signal generator, and this converted signal is used as the reference oscillation signal of the positioning device.

[Effect]

If the signal reproduced and converted by the reference signal generator of the present invention is used as a reference signal source, the television broadcast signal before reproduction is the same at two points A and B.
This is almost equivalent to the case where the positioning devices at each point are operated using a common reference signal source. Moreover, the color subcarrier signals used in television broadcast signals use atomic oscillators made of rubidinium or cesium, and use signals with extremely high frequency stability, precision (rIfi degree), and phase stability. Therefore, the characteristics of this color subcarrier signal can be utilized.

In other words, the phase difference between the television color subcarrier signals reproduced at the two points A and B is only a fixed error of the reference signal generator and remains constant regardless of the passage of time.

〔Example〕

FIG. 1 is a block diagram showing the configuration of a positioning device according to the present invention. FIG. 2 shows a block diagram of a conventional GPS positioning device using a one-channel switching reception method using a directional antenna.

Comparing FIG. 1 and FIG. 2, there is a difference in the configuration of the reference signal generator (A in FIG. 2). Other parts are similar.

The GPS signal is received by a directional antenna 1 for reception.

Using the directivity of the directional antenna 1, it is possible to separate the signal of a satellite desired to be received from the signals of other satellites.

The antenna driving device 2 is a device for directing the directional antenna 1 in the direction of a satellite from which reception is desired, and the antenna driving device 2 is controlled by the antenna control device 3.

The above-described directional antenna 1, antenna drive device 2,
The spread spectrum signal of the GPS satellite received by the antenna control device 3 is guided to the high frequency amplifier 4, where it is amplified to a required level, and then sent to the frequency converter 6a, where it is converted into the reference signal of the reference signal generator A. Based on
It is mixed with a local oscillator signal generated by the local oscillator 6e and converted to an intermediate frequency in the several tens of MHz band. This signal is band-limited by the IF filter 6b to a signal in a necessary band, and then sent to the mixer 6c.

On the other hand, the C/A code modulator 6g converts the signal generated by the Doppler shift NGO (numerically controlled oscillator) 6f, which generates the second local oscillator signal shifted by the Doppler frequency shift amount, into the PN signal generator 6j. A modulated wave is created by modulating the PN code of the desired satellite, and this signal is sent to mixer 6C.

The mixer 6c mixes the spread spectrum IF flaw signal and the modulated signal, returns the signal to the original BPSK signal, and then sends it to the A/D converter 6d. A/D converter 6d
Here, the BPSK signal, which is an analog signal, is converted into a digital signal and then sent to the control calculation section 10. mixer 6
c, A/D converter 6d, control calculation section 10, numerically controlled oscillator 6f, C/A code modulator 6g, mixer 6c, A/D converter 6d, control calculation section 10, C
/A code NC06h, PN signal generator 6j1C/
The circuits composed of the A-code modulators 6g each constitute a digital Costas loop, and the former tracks the Doppler frequency of the B1-band navigation signal, and the latter detects the period of the PN code of the satellite from which it is desired to receive. These circuits demodulate the BPSK signal output from mixer 6C, reproduce 50 bps navigation data, measure the C/A code clock phase, and the B1 band carrier phase.
It is recorded in the memory controlled by the control calculation unit IO.

Note that the intra-station delay calibration device 5 is a device that calibrates the delay time of a signal within the positioning device.

In the prior art shown in FIG.
The phase φ of the output signal of the frequency converter 6a is φ*A(t+)−φLA(t+).

In this conventional system, the reference signal generator A uses an atomic oscillator such as rubidium or cesium as the reference oscillator a, whereas in the embodiment of the present invention shown in FIG. The conventional format of a is changed, and this part is replaced with a reference signal generator A consisting of an antenna 7 for receiving television broadcasting, a tuner 8, and a signal converter 9 shown in FIG.

The television broadcast signal received by the antenna 7 is frequency-converted by a converter built into the antenna, and then guided to the tuner 8. The tuner 8 performs high frequency amplification, intermediate frequency amplification, and band limitation, and then outputs the signal as a video signal to the signal converter 9.
Output to. The signal converter 9 extracts a color subcarrier signal from the input burst video signal and reproduces a continuous signal synchronized with this signal using a phase-locked loop. It converts the subcarrier signal into the required frequency and uses it as a reference signal source for the positioning device.

In addition, in the present invention, the television color subcarrier signal is received and reproduced as a signal from a common basic signal generation source, but it is not limited to this signal, and is highly stable and used at two points A and B. It is fine as long as the signal can be received at the same time.
For example, a high-quality signal such as a television PCM audio signal or a signal used in other communication systems that has frequency stability, precision (accuracy), and phase stability that can be used as a frequency standard. May be used.

Further, as described in the explanation of the principle, this positioning device can be used not only to precisely measure the distance between certain points, but also to precisely know the position of a certain point.

〔Effect of the invention〕

By regenerating and using a television color subcarrier signal or a similar high quality signal as a reference signal source, the same signal is transmitted at two points A and B at the same time 1. Therefore, the phase difference between the reference signal generation sources reproduced by the positioning devices at both points is as follows in equation (9) above: σya=σ.

It is obtained by setting t1≠L2≠L3...≠Li+, and (π/2)((σyA-σyl+)×ΔtXC)=
From O, φt, A (ti) - φu+ (ti) = φca (tz) - φLIl (tz) = φLA (mu 3) - φLB (mu 3) - φLA
(t8)-φLll(ti)-α (constant), and the phase difference could always be kept constant.

As a result, it is possible to completely eliminate the cumulative error in the phase of the reference signal generation source over time, without using an ultra-precise and expensive atomic oscillator. We were able to provide positioning equipment.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of a positioning device according to the present invention. FIG. 2 is a long view for explaining the prior art. In the figure, l is a directional antenna, 2 is an antenna drive device, 3 is an antenna control device, 4 is a high frequency amplifier, 5 is an intra-office delay calibration device, 6a is a frequency converter, 6b is a BPF,
6C is a mixer, 6d is an A/D converter, 6e is a local synthesizer, 6f is a Doppler shift NGO 26g is a C/D converter.
The submodulator h for A code is C/A/A code C016j
is a PN signal generator, 7 is an antenna, 8 is a tuner, 9 is a signal converter, and A is a reference signal generator. Patent applicant: Anritsu Corporation Representative: Patent attorney: Ryutabe Koike

Claims (1)

[Claims] In a GPS positioning device that operates based on a reference signal generated by a reference signal generator (A), the reference signal generator (A) includes an antenna (7) and a signal received by the antenna (7). a tuner (8) that selects an electromagnetic wave that can serve as a frequency standard from electromagnetic waves;
1. A GPS positioning device comprising: a signal converter (9) that processes a signal passed through and generates a reference signal.