JPS59169233A - Ranging circuit - Google Patents

Abstract

PURPOSE:To measure an error distance at a high speed after comparing a reception position with a standard position by calculating and holding the shift between the burst reception position of own station and the standard position of the burst returned from a satellite station of the own station on the basis of a reference burst returned from the satellite station for each pescribed symbol. CONSTITUTION:A standard position extracting circuit 1 of a distance measuring circuit detects a standard position from the reception data of a reference station and then produces a standard position signal. At the same time, an own station burst position extracting circuit 2 produces an own station burst position signal showing the own station burst position from the reception data. Furthermore a standard position generating circuit 3 generates a standard position signal of the own station burst from the standard position signal given from the circuit 1. The difference is measured between the standard position given from the circuit 3 and the burst position received from the circuit 2 and then held at an error measuring circuit 4. Then a comparison position generating circuit 5 produces a comparison position signal having a shift from the standard position by an amount equivalent to the distance measurement data. A phase comparator 6 compares the outputs of the circuits 4 and 5 with each other. Thus an error distance between a ground station and a satellite is measured with high accuracy.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention The present invention relates to a method for detecting and correcting variations in burst transmission position based on variations in distance from a satellite in a time division multiple access (TDMA) ground station. This relates to distance circuits.

Prior Art and Problems In a time-division multiple access communication network, a plurality of ground stations use a common satellite station in a time-division manner to perform multiple communications. At this time, it is necessary for the satellite station to ensure that the usage time of each ground station does not overlap, but as the arrival time from each ground station to the satellite station changes as the position of the satellite station changes, It is necessary to control the burst transmission position of the station so that the time relationship of each ground station signal at the satellite station is always maintained correctly. Therefore, in a TDMA ground station, the burst transmitted by the reference station and the burst transmitted by the own station are received via the satellite station, and the predetermined standard transmission position of the burst transmitted by the own station is reflected by the satellite station relative to the burst position of the reference station. The burst position of the own station is corrected by measuring the deviation from the current position, but in order to improve the accuracy of the distance measurement, it is necessary to measure the distance in one symbol time, that is, one bit of data. It is desirable to improve the accuracy of distance measurement by performing it in units of time of 1/ri (n is any integer) of the clock whose period is the corresponding time, but conventionally, 1/n symbol When distance measurement is performed with high precision in time units, it is difficult to perform accurate distance measurement because the distance measurement data constantly fluctuates minutely based on fluctuations due to jitter, etc. in received and extracted burst positions.

OBJECT OF THE INVENTION The present invention is intended to solve the problems of the prior art, and its purpose is to transmit bursts transmitted from a reference station and bursts transmitted from its own station to a satellite station in a TDMIA ground station. When measuring the deviation from a predetermined standard transmission position of the own station burst received via the reference station and reflected by the satellite station with respect to the burst position of the reference station, this method detects and measures the center point of the fluctuating received burst position. It is an object of the present invention to provide a method that can perform distance measurement with high accuracy even when there is jitter in the received burst by using the distance data.

Composition of the Invention The distance measuring circuit of the present invention receives bursts from a reference station via a satellite station at a TDMA ground station, and calculates the distance from a predetermined standard transmission position of the local station burst reflected by the satellite station to the burst position of the reference station. The position of the distance measurement data currently held in the distance measurement circuit that performs high-precision distance measurement by counting the deviation from the standard sending position using a clock that is n times the reception data rate when measuring the distance. By re-holding new ranging data when the received and extracted position shifts regularly, the influence of small fluctuations before and after the held data in the own station's burst reception extracted position based on sick etc. can be reduced. This makes it possible to remove the .

Embodiment of the Invention FIG. 1 shows the configuration of an embodiment of the distance measuring circuit of the invention. In the figure, reference numeral 1 denotes a reference position extraction circuit which detects a reference position from reference station reception data and generates a reference position signal. Reference numeral 2 denotes a local station burst position extraction circuit, which generates a local station burst position signal indicating the local station no.\'-st position from the received data. 3 is a standard position generation circuit,
From the reference position signal of the reference position extraction circuit 1, a standard position signal indicating the standard position of the own station burst is generated. 4 is an error measurement circuit that counts the difference between the standard position of the own station's burst and the actually received burst position by multiplying it by n, and locking it.
The count results are retained as ranging data. Reference numeral 5 denotes a comparison position generation circuit which generates a comparison position signal indicating a position deviated from the standard position by the measured distance data. Reference numeral 6 denotes a phase comparison circuit, which compares the comparison position signal generated by the comparison position generation circuit 5 with the local station burst position signal indicating the actually received position, and generates a forward clock or a backward clock. 7 is an up/down counter, and a phase comparator circuit 6
The forward clock counts up and the backward clock counts down, and when the counted value exceeds a certain value, a borrow or carry occurs.

FIG. 2 shows signals of various parts in the distance measuring circuit of FIG. 1, and provides a detailed explanation of the present invention. In Figure 2, (
A) shows each burst in the received data, A is a reference station burst, and B is a local station burst that has been looped back by the satellite. In addition, (bl is a reference position signal, (C) is a local station burst position signal, and (d) is a standard position signal.

te+ is the comparison position signal, (f) is the forward clock, (g
) are ranging data, and each of these signals is indicated by the same reference numeral at a corresponding position in FIG.

Hereinafter, the operation of the distance measuring circuit of the present invention will be explained based on these figures. Received data (al is input to the reference position extraction circuit 1 and own station burst position extraction circuit 2. In the reference position extraction circuit 1, the reference station parse in the received data) A
The reference position signal (bl) indicating the reference position in the received data is extracted from the reference position signal (b).The standard position generation circuit 3 calculates the standard position of the own station burst from the reference position signal (b) according to a predetermined temporal relationship. Standard position signal (di
occurs. On the other hand, the local station burst position extraction circuit 2 generates a local station burst position signal (C) indicating the local station burst position from the local station parse (B) in the received data. The error measurement circuit 4 receives the own station burst position signal (C1) and the standard position signal (
The error with g
). Distance measurement data (gl is error measurement circuit 4
is held until the distance measurement data update signal +1) is output from the counter J.

The comparison position generation circuit 5 converts the standard position signal (dl to the distance measurement data (n times corresponding to gl) in accordance with the distance measurement data (gl).
Comparison position signals (e) are generated at positions separated by the number of clocks. The comparison position signal (e) can only be generated after the standard position signal (d) in terms of time, but the standard position signal (
Since dl is a normal periodic signal (ITDMA frame period), it can be shifted forward isometrically. Phase comparison circuit 6
compares the own station burst position signal (C) and comparison position signal (e), and if the own station burst position signal (C) is ahead of the comparison position signal (el) in time, it corresponds to a deviation. When the own station burst position signal (C) is delayed in time from the comparison position signal (e), the clock is outputted as the forward clock (fl), and when the own station burst position signal (C) is delayed in time from the comparison position signal (e), the clock is outputted as the forward clock (fl). The clock (output as hl). The forward clock (fl and backward clock fh) are input to the up/down counter 7 and count up or down the counter 7, respectively.

The initial value of the up/down counter 7 is set at the center of the upper and lower limits of the countable value, and when the own station burst position signal (C) makes slight fluctuations before and after the comparison position signal (el), In this case, the count value only moves up and down around the center value, but if the own station's burst position steadily shifts forward or backward, the count value gradually deviates from the center value and reaches the upper limit. Further, when the IJ lower limit value is exceeded, a borrow or carry is output.The borrow or carry is inputted to the error measurement circuit 4 as a distance measurement data update signal fl), and thereby the holding circuit in the error measurement circuit 4 operates. As described above, the distance measurement data at that time is updated as the value held in the error measurement circuit 4.

In this case, according to the present invention, the comparative position signal (el) is controlled so that it is always near the center of the jitter of the local station burst position signal, so the distance measurement data (g
l is data indicating the vicinity of the center of jitter of the own station burst position signal (C).

In this way, according to the ranging circuit shown in FIG.
It is possible to measure with high accuracy in units of n symbols.

DETAILED DESCRIPTION OF THE INVENTION As described in detail, the ranging circuit of the present invention calculates the deviation of the own station's burst reception position from the standard position of the satellite station return burst based on the reference station burst returned by the satellite station. 1/n (n is any integer) means for counting and holding in symbol units, and only the value held by the counting means 1/n
means for generating a signal indicating a comparison position shifted from the standard position in symbol units;
and means for updating the value held in the counting means when the deviation between the two regularly exceeds a certain value by comparing n symbols, and measuring the deviation of the burst from the standard position of the own station based on the held value. As a result, distance measurement can be performed with high accuracy even if there is a slight change in the burst reception extraction position of the own station before and after the held data due to jitter or the like.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment of the distance measuring circuit of the present invention, and FIG. 2 is a time chart showing signals of various parts in the embodiment of FIG. 1--Reference position extraction circuit, 2- Own station burst position extraction circuit, 3- Standard position generation circuit, 4- Error measurement circuit, 5--
Comparison position generation circuit, 6-phase comparator, 7-up/down counter Patent applicant Fujitsu Limited

Claims (1)

[Claims] In a time-division multiple access ground station where multiple ground stations use a common satellite station in a time-division manner, the satellite station's own satellite station return burst from its standard position is determined based on the reference station burst returned by the satellite station. Station burst reception position shift by 1
/n (n is any integer) symbol unit counting and holding means; means for generating a signal indicating a comparison position shifted from the standard position by the value held by the counting means in 1/n symbol units; means for comparing the comparison position and the receiving position in units of 1/n symbols and updating the value held in the counting means when the difference between the two regularly exceeds a certain value; A distance measuring circuit characterized by measuring the deviation from a standard position.