SU1688419A1

SU1688419A1 - Device for measuring phase-frequency characteristic of communication channel

Info

Publication number: SU1688419A1
Application number: SU894771174A
Authority: SU
Inventors: Владимир Петрович Панкратов
Original assignee: Ленинградское научно-производственное объединение "Красная заря"
Priority date: 1989-12-19
Filing date: 1989-12-19
Publication date: 1991-10-30

Abstract

Изобретение относитс к технике св зи. Цель изобретени - повышение точности измерени . В устройство введены на приемной стороне усилитель 2, дифференцирующа цепочка 4, мостовой выпр митель 5, индикатор 16 значений частоты, регистрирующий блок 15, а в блок 6 вычислени фазы колебаний дополнительно введены блок 11 выбора пакетов, счетчик 7 длительности пакетов , фиксатор 10 перепада фазы, блок 12 базы данных. В предложенном устройстве дл определени фаэочастотной характеристики контролируемого канала св зи используетс метод сравнени скорости изменени частоты измерительного сигнала с генератора 1 на входе и выходе, а не сравнени фаз этих колебаний. Повышение точности достигаетс за счет исключени вли ни на результат измерений расхождени несущих частот каналообразующей аппаратуры св зи контролируемого канала св зи.1 ил. еThe invention relates to communication technology. The purpose of the invention is to improve the measurement accuracy. An amplifier 2, a differentiating chain 4, a bridge rectifier 5, a frequency value indicator 16, a recording unit 15 are inserted into the device on the receiving side, and a packet selection unit 11, a packet duration counter 7, a phase difference lock 10 are added to the oscillation phase calculator 6. , block 12 of the database. In the proposed device, the method of comparing the frequency of the measurement signal from generator 1 at the input and output, rather than comparing the phases of these oscillations, is used to determine the frequency characteristics of the monitored communication channel. The increase in accuracy is achieved by eliminating the effect on the measurement result of the divergence of the carrier frequencies of the channel-forming communication equipment of the controlled communication channel. 1 sludge. e

Description

При аналогичных преобразовани х вы- ражени сигнала на выходе канала вводитс г - новое обозначение текущего времени. Кроме того, фазочастотную характеристику представим в виде отдельных значений $к . у которых индекс К однозначСоотношение (13) позвол ет определ ть перепады фазы A 0k на каждом полупериоде Агк измерительного сигнала Однако использование его дл определени ФЧХ затруднительно. Это вытекает из того,With similar transformations of the signal expression at the channel output, r is introduced - a new designation of the current time. In addition, the phase-frequency characteristic is represented as individual values of $ k. in which the index K is one value. The ratio (13) allows determining the phase difference A 0k at each half-period Aq of the measuring signal. However, it is difficult to use to determine the phase response. This follows from the fact

что дл приемлемых скоростей изменени частоты (а 1000-2000 Гц/с) испытательного сигнала, предназначенного дл измерени каналов ТЧ. число учитываемых полуволн Лгк будет составл ть несколько тыс ч (от 1 до 6). Естественно, что измер ть, фиксировать и рассчитывать такое количество перепадов 0у, не представл етс целесообразным , Хот главной причиной отказа от пр мого использовани соотношени (13) вл етс дополнительна погрешность , св занна с суммированием погрешностей расчета отдельных ДгЯс при переходе к ФЧХ канала ТЧ. котора определ етс по формулеthat for acceptable rates of change in the frequency (a 1000–2000 Hz / s) of the test signal for measuring the PM channels. The number of half-waves recorded in Lgk will be several thousand hours (from 1 to 6). Naturally, it is not reasonable to measure, record and calculate such a number of 0u drops, Although the main reason for refusing to directly use the relation (13) is the additional error associated with the summation of the calculation errors of individual MGs when switching to the MF channel of the PM . which is determined by the formula

N (()N (()

Ь И I, к - 1B and i, k - 1

где N (а)) - количество полупериодов Лгк колебаний испытательного сигнала, учитываемое дл соответструющего текущего значени ш.where N (a)) is the number of half-periods LGK of oscillations of the test signal, taken into account for the corresponding current value w.

Поэтому практически оказалось целесообразным использовать и контролировать многоинтервальные отрезки времени А т«м и Агкм , включающие М единичных интервалов At (Лгк).Therefore, it has practically proved expedient to use and control multiinterval time intervals A t м m and Agkm, including M unit intervals At (Lgk).

Легко показать, что дл М-интервально- го отрезка времени соответствующий ему перепад фазы определ етс по формулеIt is easy to show that for an M-interval, the corresponding phase difference is determined by the formula

А л:МA l: M

Агк AtKAgk AtK

Полученные формулы (14) и (15) используютс дл составлени алгоритма вычислени ФЧХ и физически реализуютс в предлагаемом устройстве.The resulting formulas (14) and (15) are used to compile an algorithm for calculating the frequency response and are physically implemented in the proposed device.

В зависимости от скорости изменени частоты испытательного сигнала (коэффициента а) и частотного участка измер емой характеристики величина М выбираетс различной.Depending on the rate of change of the frequency of the test signal (coefficient a) and the frequency section of the measured characteristic, the value of M is chosen different.

Значени длительностей отдельных интервалов входного сигнала AtKM и частот, соответствующих их границам, вычисл ютс заранее при заданном коэффициенте а и ввод тс в блок 12 базы данных. По мере надобности в процессе измерений длительностей интервалов и вычислений перепада фазы информаци из блока 12 базы данных выдаетс в расчетный блок 9 и индикатор 16 значений частоты.The durations of the individual intervals of the input signal AtKM and the frequencies corresponding to their boundaries are calculated in advance at a given coefficient a and entered into block 12 of the database. As required in the process of measuring the durations of intervals and calculating the phase difference information from the database unit 12 is output to the computation unit 9 and the indicator 16 frequency values.

Claims

Apparatus of the Invention A device for measuring the phase-frequency characteristic of a communication channel, comprising

On the transmitting side, the oscillating frequency generator, the output of which is the input of the connection to the controlled communication channel, and on the receiving side the generator, the unit for starting and stopping the measurements, the generator of counting pulses, the first output of which is connected to the first input of the unit for starting and stopping the measurements , an indicator of phase values, a unit for calculating a phase oscillation phase, made in the form of a control unit, a packet duration latch and a calculation unit, characterized in that. what. in order to improve the measurement accuracy, an amplifier is inserted at the receiving side, the input of which is the output of the connections of the controlled communication channel, and the output of the amplifier is connected to the input of the driver, connected in series to the differentiating chain,

The input 20 of which is connected to the output of the generator, and the bridge rectifier, the output of which is connected to the second input of the start and stop measurement unit and the information input of the oscillating phase calculator, the first output of which is connected to the information input of the phase value indicator, serially connected frequency value indicator, whose information input is connected to the second output of the oscillation phase calculating unit, and the recording unit, the first and second information inputs of which are connected respectively to the output The odes of the phase value indicator and the frequency value indicator,

35a, the database unit is additionally entered into the oscillation phase calculation block, the input of which is connected to the first output of the control unit, the phase difference lock, the output of which is the first output

40 of an oscillation phase calculating unit, a packet selection unit connected in series, the input of which is an information input of a oscillation phase calculating unit, and a packet duration counter,

45 whose output is connected to the latch input of the packet duration, the output of which is connected to the first input of the computation unit, the second input and the output of which are connected respectively to the first output of the database unit and the input of the phase difference latch, the output of which is the first output of the oscillation phase calculator, the second output of which is the second output of the database block, the second and third

The 55 outputs of the control unit are connected respectively to the control inputs of the packet selection unit and the calculation unit, respectively; the fourth, fifth and sixth outputs of the control unit are the first, second and third

11 168841912

the control outputs of the block are computed first and second, respectively.

neither the phase of the oscillations which are connected by the control inputs of the calculating unit

correspondingly with the control inputs of the oscillation phase, and the correspondence of the phase value indicator is connected, indicator to the second output of the generator

values of frequency and recording block-5 pulses and the second output of the start block

ka, clock input of the counter duration of pa-and stop measurements, chum and the launch input of the control unit