SU686139A1

SU686139A1 - Digital frequency detector

Info

Publication number: SU686139A1
Application number: SU762331298A
Authority: SU
Inventors: Костас Костович Венскаускас
Original assignee: Предприятие П/Я Г-4488
Priority date: 1976-03-02
Filing date: 1976-03-02
Publication date: 1979-09-15

Description

(54) ЦИФРОВОЙ ЧАСТОТНЫЙ ДЕТЕКТОР(54) DIGITAL FREQUENCY DETECTOR

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Изобретение относитс к электросв зи и может использоватьс дл детектировани частотио-модулированных (ЧМ) сигналов и определени ухода частоты в системах автоматической подстройки частоты.The invention relates to telecommunications and can be used to detect frequency-modulated (FM) signals and determine frequency drift in automatic frequency control systems.

Известен цифрювой частотный детектор, содержащий последовательно соединенные с источником сигнала полосовой фильтр и первые ограничитель и формирователь импульсов, последовательно соединенные опорный генератор и вторые ограничитель и формирователь импульсов , а также выходной формирователь импульсов (1).Known digital frequency detector comprising a band-pass filter and a first limiter and a pulse shaper connected in series with a signal source, a reference oscillator connected in series and a second limiter and a pulse shaper, as well as an output pulse shaper (1).

Однако известный цифровой частотный детектор имеет низкую помехоустойчивость.However, the known digital frequency detector has low noise immunity.

Цель изобретени повышение помехоустойчивости .The purpose of the invention is improving noise immunity.

Дл ЭТОГО в цифровой частотный детектор, содержащий последовательно соединенные с источником сигнала полосовой фильтр и первые ограничитель и формирователь импульсов, последовательно соединенные опорный генератор и вторые ограничитель и формирователь импульсов , а также выходной формирователь импульёFor THIS, a digital frequency detector comprising a band-pass filter connected in series with a signal source and the first limiter and pulse shaper, the reference oscillator connected in series, and the second limiter and pulse shaper as well as the output pulse shaper

сов, введены блок разделени импульсов, первый и второй блоки оценки частоты, блок управлени и решающий блок, причем первый вход блока разделени импульсов подключен к вьнходу второго формировател импульсов, выходы блока разделени импульсов подключены к попарно соединенным первым и вторым входам блока оценки частоты, к соединенным третьим входам которых подключен выход первого формировател импульсов, к выходам бло0 ков оценки частоты подключены попарно соединенные первые и вторые входы решающего блока и блока управлени , первый выход которого соединен с вторым входом блока разделени импульсов, а второй выход - с третьим The pulses separation unit, the first and second frequency estimators, the control unit and the decision block are entered, the first input of the pulse separation unit is connected to the input of the second pulse generator, the outputs of the pulse separation unit are connected to pairwise connected first and second inputs of the frequency estimator, connected to the third inputs of which the output of the first pulse shaper is connected, the outputs of the frequency evaluation blocks are connected in pairs the first and second inputs of the decision unit and the control unit, the first the output of which is connected to the second input of the pulse separation unit, and the second output - to a third

5 входом решающего блока, выход этого блока подключен к входу выходного формировател импульсе.5 input of the decision block, the output of this block is connected to the input of the output pulse shaper.

На чертеже приведена структурна электрическа схема предложенного устройства.The drawing shows a structural electrical circuit of the proposed device.

Claims

The digital frequency detector contains a band-pass filter 1, the first limiter 2 and the pulse shaper 3, the reference generator 4, the second limiter 5 and the pulse shaper 6, a pulse separation unit 7, the first and second frequency estimation blocks 8 and 9, the control block 10, a crucial block 11 and the output driver 12 pulses. The device works as follows. The principle of operation of a digital frequency detector will be considered on the basis of receiving discrete binary frequency-modulated (FM) signals. When a digital signal is received at the input of a digital radio frequency detector: the band-pass filter 1 selects a frequency spectrum including the main energy of the binary FM signal, which is limited by limiter 2, and in the form of square pulses goes to the pulse shaper 3, which forms a short imulse when the signal crosses zero the positive side, and then goes to the blocks 8 and 9. The signal of the reference generator 4 is limited by the limiter 5 and fed to the driver 6 pulses, the latter generates short pulses during the first zero signal section in a positive and a negative side. Blocks 8 and 9 together with decision block 11 decide which information signal (1 or O) the received signal belongs to. The unit corresponds to the highest transmitted frequency, zero - the lowest. The output driver 12 forms a continuously accurate send of the required value. The proposed digital frequency detector enhances the noise immunity of the digital desparator of FM signals and possesses great rational possibilities, since it can be used as a frequency detector in automatic tuning of the frequency signal and in telemetry systems. DETAILED DESCRIPTION OF THE INVENTION A digital frequency detector comprising a band-pass filter connected in series with a signal source and a first limiter and pulse shaper, a reference generator and a second limiter and pulse shaper in series, as well as an output pulse shaper, characterized in that, in order to improve noise immunity, a pulse separation unit, a first and a second frequency estimation unit, a control unit, and a decision unit were introduced, the first input of the pulse separation unit Connected to the output of the second pulse driver, the outputs of the pulse separation unit are connected to pairwise connected first and second inputs of frequency evaluation units, to the connected third inputs of which the output of the first pulse generator is connected, to the outputs of the partial pulse evaluation units connected in pairs the first and second inputs of the decision unit and the unit control, the first output of which is connected to the second input of the pulse separation unit, and the second output - to the third input of the decision block, the output of this block is connected to the output of the output th pulse shaper. Sources of information taken into account during the examination 1. Mashbits, L. M. Digital signal processing in radiotelephone communications, M., Sv, 1974, p. 105, fig. 42