JPH07198832A - Distance-measuring apparatus using fixed data pattern - Google Patents

Abstract

PURPOSE:To provide a delay time measuring apparatus whose delay-time measuring resolution is enhanced and whose maximum distance-measuring range can be made larger in an apparatus in which the transmission and reception timing delay time is measured by using a data pattern such as a PN code or the like and which measures the distance of a transmission line. CONSTITUTION:In a data transmission circuit, transmission data D2 which is generated by a reference clock source 1 and a transmission frame pattern generator 2 is received by a bit synchronous circuit 4 and a frame synchronous circuit 5 via a transmission line 3. In the data transmission circuit, the counted value (c) of a transmission frame counter 9 is sampled by a sampler 10 at a reception frame-synchronous-pattern detection timing (b). A transmission-clock sampling-phase measuring part 11 is provided with a T/2 delay circuit 112 which delays the synchronous pattern detection timing (b) by half the integration time T, with a waveform memory 111 which records the waveform of a transmission clock (d), with a complex multiplier 114 which performs a complex multiplication between outputs of a numerically controlled oscillator 113, with an integrator 115 and with an a tan an operation device 116 which operates a phase angle on the basis of an integrated result. An operation device 8 which computes a delay-time measured value on the basis of outputs of the sampler 10 and the atan2 operation device 116 is provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention uses a data clock and a frame synchronization pattern necessary for transmitting data in a mobile communication or satellite communication system for transmitting and receiving a data pattern, or a spread spectrum communication system. The present invention relates to a distance measuring device for measuring a round-trip distance between a mobile body or a flying body and a base station by using a transmission / reception timing of a PN code for spread spectrum and a PN code.

[0002]

2. Description of the Related Art FIG. 3 shows a frame synchronization timing in which a delay time measurement system measures a generation timing difference of a frame synchronization pattern (a type of fixed data pattern) between a transmission side and a reception side in a transmission / reception data transmission system. It is a block diagram of the distance measuring device utilized, FIG. 4 is a time chart which shows the signal of each part of this distance measuring device.

The delay time measuring function in FIG. 3 is based on the transmission timing of the transmission frame synchronization pattern h,
A measurement gate i as shown in FIG. 4 is created at the timing when the frame synchronization pattern m is detected on the receiving side, and the number of waves of the high-speed reference clock j is counted while the measurement gate i is open. The width of i, that is, the transmission / reception frame synchronization timing difference is measured. When the number of cycles of the high-speed reference clock j is f _REF , the width of the measurement gate i is T, and the value of the measurement count k is N, the following relationship is established: T = (1 / f _REF ) N "SEC" Therefore, the round trip distance R with respect to the measurement delay time T is obtained as follows.

R = (speed of light) * T "m"

[0005]

In the delay time measuring method as shown in FIG. 3, in order to improve the distance measuring resolution, that is, the delay time measuring resolution, a high frequency of the reference clock j is required, and the maximum distance measuring distance is required. In order to increase, the counter 7 for counting the wave number of the high-speed reference clock j needs to operate at high speed and have a long counter length. Generally, when the counter length is increased, it is difficult to handle a high-speed reference clock due to the problem of the propagation time of the carry signal that propagates the change of the least significant digit to the most significant digit, thus increasing the maximum distance measurement range and increasing the measurement resolution. It has been difficult to measure improvements.

Further, in the method of measuring the width of the measurement gate by opening the measurement gate at the transmission event (input event h) and closing the measurement gate at the reception event (reference event m).
It is necessary to make a waiting time necessary to perform the next measurement, and it is inevitable that the measurement cannot be performed during this time.

[0007]

In order to solve the above-mentioned problems, the means provided by the present invention transmits a data pattern, which is based on the transmission timing of a fixed data pattern, to a transmission line, and the receiving side uses a data clock The fixed data pattern is detected at the same time as the reproduction, and the delay time generated in the transmission path is measured by measuring the delay time between the detection of the fixed data pattern and the transmission timing. In the distance measuring device that measures the distance of the transmission line based on the above, by sampling the contents of the fixed data counter on the transmitting side at the detection timing of the fixed data pattern on the receiving side, a rough delay time is measured as a rough delay time, and fixed reception is performed. The means for measuring the phase of the clock on the transmission side at the data pattern detection timing delays the A distance measuring device using a fixed data pattern, characterized in that the total time is measured as a high resolution delay time, and the distance calculated by combining the coarse delay time and the high resolution delay time is output as the distance of the transmission path. Is.

[0008]

The delay time measuring means of the present invention counts the transmission side frame synchronization pattern (fixed data pattern) interval, that is, the frame size by the transmission data clock, and samples the contents of this counter at the detection timing of the reception side frame synchronization pattern. However, it has a system for measuring the delay time using the data clock on the transmitting side as a reference signal (corresponding to the reference clock j in FIGS. 3 and 4). When the transmission-side data clock frequency is f _TX and the transmission frame size is N, a delay time measuring device having a delay time measuring resolution (1 / f _TX ) and a maximum measuring delay time range (N / f _TX ) can be realized.

Generally, the resolution in delay time measurement cannot be improved just by using the transmission data clock as the reference signal. However, the resolution in the delay time measurement can be improved by having the phase measurement function of measuring the phase of the transmission data clock at the reception frame synchronization detection timing.

Assuming that the measurement phase resolution is δθ and the measurement phase is θ, the measurement delay time resolution {(1 / f _TX ) · (δθ / 2
π)}, the maximum measurement delay time range (1 / f _TX ) becomes a delay time measuring device, and the measurement delay time resolution {(1 / f _TX ) · (δθ / 2π)}, It is possible to realize a delay time measuring device having a maximum measurement delay time range (N / f _TX ).

When the measurement phase difference is θ and the wave number count sampling value is X, the measurement delay time T can be calculated by the following equation.

T = (θ + 2πX) / (2πf _TX ) “SEC” In the present invention, a method of sampling the value of the transmission side frame counter and sampling the phase of the transmission side data clock when the reception frame synchronization pattern is detected is adopted. ing. Therefore, it was inevitable in the conventional device of FIG.
The device of the present invention does not have the drawback of having a non-measurement band necessary for the next measurement, and the measured value θ (k−
By holding the values 1) and X (k-1), the additional function that the inter-received frame period P can be measured can be obtained.

P = {θ (k) + 2πX (k) -θ (k-
1) + 2πX (k−1)} / (2πf _TX ).

[0014]

The present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a configuration of an embodiment of the present invention,
FIG. 2 is a time chart of signals of respective parts in the embodiment of FIG.

The transmission data clock d generated by the reference clock generation source (also serving as a data generator) 1 is transmitted to the frame pattern generator 2 and the frame counter 9. The frame generator 2 receives the transmission data clock d and the data D1, generates a transmission data pattern D2 including a frame synchronization pattern, and transmits it to the transmission line 3. The bit synchronization circuit 4 reproduces the data clock from the received data pattern, transmits the reproduced clock a and the reproduced data D3 to the frame synchronization section 5, and detects the frame synchronization pattern position in the received data pattern.

The frame counter 9 counts the transmission data clock d from the reference clock generation source 1, and the transmission frame timing R from the frame pattern generator 2.
It is reset by and thus constitutes a ring counter. The reception frame synchronization pattern detection timing (reception event b) of the frame synchronization unit 5 described above is determined by the sampler 1
0, where the transmission frame count value c is sampled, and a delay time measuring / decomposing function (1 / f _TX ) and a delay time measuring device having a maximum measurement delay time range (N / f _TX ) are realized.

On the other hand, the transmission data clock d is stored in the waveform memory 111 having the recording capacity T, the reception frame detection timing b is transmitted to the waveform memory 111 via the T / 2 delay circuit 112, and the transmission data clock d is transmitted. Storage is terminated. Therefore, in the waveform memory 111, the interval [+
The waveform of the transmission data clock d is stored over T / 2, −T / 2]. The numerically controlled oscillator 113 is an oscillator that has a zero phase at the center of the data in the waveform memory 111 and that generates complex signals of SIN and COS (e and f in FIG. 2) at the same frequency as the transmission data clock d. . The complex multiplier 114 performs the following calculation between the contents of the waveform memory 111 and the output of the numerically controlled oscillator 113.

[0018] _{cos (θ-θ ref) =} cosθcosθ ref + sinθsinθ ref sin (θ-θ ref) = sinθcosθ ref -cosθsinθ ref where, cos [theta], sin [theta is the waveform of the transmitted data clock d stored in the waveform memory 111, cos θ _ref , sin θ
_ref is a complex reference signal generated by the numerical control generator 113. The integrator 115 outputs cos (θ−θ _ref ), sin (θ−) from the complex multiplier 114 during the integration time T.
θ _ref ) is integrated, and the phase angle θ is calculated by the ATAN2 calculator 116.

Θ = tan ⁻¹ {Σsin (θ−θ _ref ) / (Σcos θ−θref)} “0 ≦ θ <2π” θ _ref is the transmission data clock d for the reception frame detection timing b as described above. Since it becomes zero at the center of the waveform, the phase angle θ obtained from the integrated value of the integration time T means the phase of the transmission data clock d sampled at the reception frame detection timing b. Therefore, assuming that the measurement phase resolution is δθ and the measurement phase is θ, the measurement delay time resolution {(1 / f _TX ) · (δθ / 2
π)}, and realizes a delay time measuring device having a maximum measurement delay time range (1 / f _TX ).

The calculation unit 8 calculates the phase measurement value θ (k) (Q2 in FIG. 1) and the sampling frame count value X (k).
(Q1 in FIG. 1) is input, and the delay time measurement value T (k) (Q3 in FIG. 1) is calculated by performing the following calculation.

T (k) = {θ (k) + 2πX (k)} / 2πf _TX “SEC” Also, as an additional function, θ (k−1), X one measurement cycle before
By storing (k-1), the reception frame period P (k) can be calculated.

P (k) = {θ (k) + 2πX (k) -θ
(K-1) + 2πX (k-1)} / {2πf _TX }

[0023]

As described above, according to the present invention, in the distance measuring device using the fixed data pattern such as the frame synchronization pattern, the transmission fixed data pattern at the detection timing of the reception fixed data pattern such as the reception frame synchronization pattern. The counter (transmission frame counter etc.) is sampled and the transmission data clock phase is measured,
By combining two measurement values, it is possible to improve the distance measurement resolution and increase the maximum distance measurement range.

By using this method, the non-measurement time required in the conventional delay time measurement is not required, and it has a feature of having a function of measuring the reception frame period.

Further, for the purpose of sampling and measuring the phase of the transmission data clock at the reception fixed data pattern timing (reception frame synchronization timing in the embodiment), the transmission data clock frequency is controlled by the numerically controlled oscillator instead of using the reception data clock. This means that the frequency of the transmission / reception data clock may be different in order to generate it. That is, it is possible to allow the deviation of the reception data clock from the transmission data clock due to the Doppler shift effect in the transmission path, and further, to employ various modulation / demodulation methods in which the data clock is different as the transmission path. Even now, distance measurement is possible.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is a time chart showing signals of respective parts in the embodiment of FIG.

FIG. 3 is a block diagram showing a conventional device.

FIG. 4 is a time chart showing signals of respective parts in the conventional apparatus of FIG.

[Explanation of symbols]

 1 reference clock source 2 frame pattern generator 3 transmission line 4 bit clock reproduction circuit 5 frame pattern detection circuit 6 measurement gate generator 7 high speed counter 8 arithmetic circuit 9 transmission frame counter 10 sampler 11 transmission clock sampling phase measurement unit 111 waveform memory 112 T / 2 delay circuit 113 Numerically controlled oscillator 114 Complex multiplier 115 Integrator 116 atan2 calculator

Claims (2)

[Claims] 1. A data pattern, which is based on the fixed data pattern transmission timing, is transmitted to a transmission line, and a receiving side reproduces a data clock and detects the fixed data pattern. In a distance measuring device that measures the delay time generated in the transmission path by measuring the delay time with the transmission timing and measures the distance of the transmission path based on this delay time, a fixed data counter on the transmission side. By sampling the contents of the above at the detection timing of the fixed data pattern on the receiving side, a rough delay time is measured as a rough delay time, and a delay with a large resolution is measured by means of measuring the phase of the clock on the transmitting side at the detection timing of the fixed data pattern on the receiving side. Time is measured as high resolution delay time, and coarse delay time and high resolution delay time Distance measuring apparatus using a fixed data pattern and outputting the distance calculated as the distance of the transmission path by synthesizing. 2. The method according to claim 1, wherein the fixed data pattern is a frame synchronization pattern, and the fixed data counter is a frame counter, which is applied to a communication system that transmits and receives data by a data transmission method. Distance measuring device using the fixed data pattern of.