SU1053308A1 - Method of measuring quantization characteristic of pulse-code-modulated signal receiver - Google Patents

Abstract

METHOD OF MEASUREMENT OF XAPAKTJE PHCfHKH QUANTIZATION OF THE RECEIVER OF SIGNS WITH A PULSE-CODE MODULATION consisting in the fact that the receiver's input serves sequentially a pair of alternating code combinations corresponding to two levels of quantizing, and there are spreads. in order to shorten the measurement time by eliminating measurements of linearly dependent quantization levels, as an alternating pair of code combinations, choose a combination coding whose difference is psh is equal to the value of one of the receiver reference sirnals for each of the segments constituting the quantization characteristic, and after measuring the difference values of the corresponding quantization levels, they memorize these values and determine the quantization characteristic in accordance with the expression k. . . + i 1 i 2 a (e, g). OK ; , ,, TLl .u.} M; de l; - values of measured quantization level differences g; e is the iaara P quantization number in the quantization characteristic segment; g is the number of the quantization characteristic segment.

Description

The invention relates to measurements in a communication technique and can be used for separate measurements of parameters and characteristics of PCM apparatus half sets. Separate transmitter and receiver measurements are necessary to obtain a regulated channel quality for any combination of semi-sets.

A known method for measuring the quantization characteristic of a PCM receiver; that is, a digital signal corresponding to an analog g mono signal is supplied to the receiver input, and the quantization levels 1J are measured at the receiver output (using an adjustable attenuator and level gauge).

The disadvantages of this method in-. The accuracy of measurements is low, due to the fact that the measurements do not differ in the levels corresponding to different half-waves; large measurement time, due to both the number of measured levels and the need to adjust the attenuation introduced by the a-tenuator for each level measurement.

The closest to the present invention is the method implemented in the device for measuring the quantization characteristic of a PCM receiver, consisting in that pairs of alternate code combinations corresponding to two quantization levels are fed to the receiver input, and the difference values of these levels are measured at the receiver output quantizing 2.

A disadvantage of the known method is a large measurement time, since this operation for measuring the entire quantization characteristic must be repeated n times, where m is the number of quantization steps.

For the quantization characteristic with the parameter A 87.6 / 13 and the eight-bit coding recommended by CCTT and used in the PCM-30 equipment, which is the basis of digital transmission systems, p 256.

The purpose of the invention is to reduce the measurement time by eliminating the measurements of linearly dependent quantization levels.

The goal is that according to the method consisting in that pairs of alternating code combinations corresponding to two quantization levels are fed to the receiver input, and the difference values of these quantization levels are measured at the output of the receiver, code combinations are chosen as alternating code combinations the difference of which is equal to the value of one of the receiver reference signals for each of the segments constituting the quantization characteristic, and after measuring the values of the difference corresponding to ovney quantization storing these values and determining a quantization characteristic in accordance with the expression

in the quantization characteristic segment;

g is the number of the quantization characteristic segment.

Fig. 1 shows a block diagram (devices implementing the proposed method; Fig. 2 shows the distribution of reference signals in segments and bits of code concatenation mantissa (the characteristic of the code combination determines the number of the segment.

In FIG. 2, each row is a set of reference signals, of which quantization levels in a segment are constituted, the first row corresponds to the seventh segment, the second to the sixth, and so on. At the same time, they are included in each level of the segment.

The device contains a digital generator 1, the measured receiver 2, the level meter 3, the first switch 4, the control unit 5, the algebraic adder b, the indicator 7 of the faulty bits, the second switch 8, the measurement delay delay element 9, the comparator 10, element 11, memory block 12, calculator 13 quantization levels.

The quantization characteristic measurement is carried out in three steps. At the first stage, the correctness of the logic and switching circuits of the receiver is checked and at the same time a part of the reference signal is measured — the reference signals of the diode of the half-wave lim4R + Kl K () and all the reference signals of the second half-wave, D, (0- # mill), in the third stage, the quantization levels are determined from the measured values of 4m and 4.

At the first stage, the signal from the first output of the control unit 5, from the output of the digital generator 1 to the input of the measured receiver 2, is successively supplied with pairs of alternating code combinations distinguishing {with one bit of the mantissa grouped by the values of m (first all pairs of code combinations appropriate, then, etc.). From the output level gauge 3, the value of the measured level difference is fed to input 1 of the first switch 4, to input 2 of which the switching signal, -1l, comes from output 2 of control unit 5. As long as lim R + K-2 (and for the first pair of code combinations, say P R + K-1 (m 10 /, the signal from the second output of the first switch 4 goes directly to the input of the second commutator 8. At the same time that the input of the digital generator 1c of the first output of the control unit 5 receives a command to generate a second pair of code combinations corresponding to m R + Kl (i.e., a pair of code combinations from different segments, the second input of the first switch 4 receives a signal according to 2 the value of the measured level difference comes from the first output and the first switch 4 to the first input of the algebraic adder b, the second input of which from the first output of the memory block 12 receives the value of this signal, which in total with the measured level difference gives the output of the algebraic adder 6 the value of the reference signal L for m R + Kl (I, which arrives at the first input of the second switch 8. To the second input of the switch 8, a signal is received, according to which the reference signals Af, KmiR + Kl are fed to the first input of the comparator 10, to the second input of which the previous value Lp ,, delayed read only in the element 9 delays the measurement cycle (time in one pair of interleaved codewords within which enters at the receiver input). From the output of the comparator 1, the signal is fed to the input of the control unit 5. If all the values of the DW, PR fixed value of m are equal to each other (zero signal at the comparator output, after the end of the comparison cycle for a fixed m signal from the fourth output of the control unit, the signal goes to the third input element And 11, unlocks it and the value of the reference signal from the output of the delay element 9 through the element 11 to the first input of the memory block 12. If the output of the comparator is not a zero signal, then the element H 11 remains locked, and the indicator 7 of the faulty bits from the sixth output of the control unit 5 or to receive information about faulty bit dah

(faulty receiver logic). After the end of all comparison cycles, if only zero signals were received from the output of the comparator, the second measurement stage begins, which determines the remaining values of the reference signals. The signal from the first output of the control unit 5 from the output of the digital generator 1 to the input of the measured receiver 2 receives pairs of code combinations corresponding to 0 and () the same half-wave, from the output of level 3 meter to the first input of the first switch 4 receives the measured level differences, and The second input from the second control unit 5 receives a signal on which the measured level differences from the first output of the first switch 4 arrive at the first input of the algebraic adder b. The second input of the algebraic adder 6 comes from the first output of memory block 12, previously measured reference signals such that the output of algebraic accumulator 6 produces reference signals Lj and l f c (L}.: From the output of the algebraic adder 6 | through the second switch 8 and element; And 11 reference Signals are recorded in memory block 12. Then, from the output of the digital generator 1, the pairs of code combinations corresponding to the reference signals of the second half-wave arrive at the input of the measuring terminal 1, and the signal from the first switch 4 for li miR + Kl (), it is removed from the second output and goes directly to the input of the second switch 8, a and (the signal is taken from the first output and goes to the input of the algebraic adder B. The values of the first output of the second switch 8 come through the | first element 11 to the first input of the memory block 12. After all 2 (R + KI reference signals i are recorded in the memory block 12, the third step of measuring the quantization characteristic is started, on which (values a, t are read from the second output of 12 memories to the input of the calculator 13, where they are determined Quantization levels Q (e, g) and Q (,. The proposed method is suitable for any PCM receiver in which decoding is performed by segment weighting.

The positive effect of using the proposed method for-. It is very significant in reducing the time during which the telephone channel cannot be used in connection with the measurement.

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Claims (2)

METHOD FOR MEASURING THE CHARACTERISTICS OF THE QUANTIZATION QUANTIZATION OF A SIGNAL RECEIVER WITH A PULSE-CODE MODULATION, which consists in the fact that the receiver input is fed sequentially pairs of alternating code combinations corresponding to two quantization levels, and the values of the difference of these quantization levels are measured at the output of the receiver. and it is skinny that in order to reduce the measurement time by eliminating measurements of linearly dependent quantization levels, code combinations are selected as alternating pairs of code combinations, the difference which is equal to the value of one of the reference signals of the receiver for each of the segments making up the quantization characteristic, and after measuring the difference values of the corresponding quantization levels, these values are stored and the quantization characteristic is determined in accordance with the expression SU w. 1053308 where 4; - the values of the measured differences of the quantization levels; 2 - quantization step number in the quantization characteristic segment; g is the segment number of the quantization characteristic.