SU485539A1 - Frequency detector - Google Patents

Description

(54) FREQUENCY DETECTOR

one

The invention relates to radio engineering and can be used in frequency and phase locked loop devices.

A frequency detector is known, which contains an FDP of the input signal shaper, the output of which is connected to four coincidence circuits, the driver. a reference signal with four outputs, the signals of which are phase shifted by O, 180, 90 and 270, connected respectively to the second inputs of the coincidence circuits, and the determinant of the sign of the difference frequency, made in the form of two output coincidence circuits.

However, the known frequency detector does not have a high detection accuracy in a wide frequency range.

In order to increase the detection accuracy in the umpoKOM frequency range, the proposed detector is equipped with two triggers and a differential frequency driver, and the zero and single inputs of the first trigger are connected respectively to the outputs of the first and second circuits (coincidence, and the zero and single inputs

the second flip-flop is connected to the outputs of the third and fourth coincidence circuits, while the outputs of the first flip-flop are connected to one of the inputs of the output coincidence circuits, BTOpf re whose inputs are connected to the output of the second flip-flop via a pulse shaper.

The drawing shows a functional diagram of the proposed frequency detector.

The frequency detector contains an input signal conditioner 1, the output of which is connected to four coincidence circuits, 2-5, a reference signal conditioner 6 with four outputs, the signals of which

shifted in phase by O, 18O, 9O and 270 °, connected respectively to the second inputs of the matching circuits 2-5, the differential frequency sign determinant, made in the form of two output matching circuits 7 and 8, two triggers 9 and 10, and the differential frequency pulse shaper 11. The zero and single inputs of the trigger 9 are connected respectively to the outputs of the matching circuit 2 and 3, and the zero and single inputs of the trigger 10 to the outputs

348553

 matching circuits 4 and 5. The outputs of the trigger 9 are connected to one of the inputs of the output matching circuits 7 and 8, the second inputs of which are connected to the output of the trigger 10 via a differential frequency pulse generator Ts.

The frequency detector works in the following way.

. The input signal is fed to a driver 1, from which a signal in the form of narrow impulses is fed to four matching schemes 2-5. The second inputs of the coincidence circuits from the outputs of the imaging unit 6 are supplied, respectively, phase-shifted reference signals of a rectangular shape. Impulses at the output of any one: coincidence schemes appear only in the following: b: -the time of the appearance of a narrow pulse from the top of the driver 1, the potential of the reference signal at the second input corresponds to the resolving potential of the coincidence circuit. Since the frequencies of the input and reference signals are not equal, i.e., the narrow pulses of the driver 1 change their position relative to the beginning of the reference signal period, at the output of coincidence circuit 2-5 there appear bursts of pulses with the difference frequency of the input and reference signals, and 2–5 coincidence circuit packs are phase shifted by O, 18O, 90, and 270, respectively. The bursts of pulses from coincidence circuits 2 and 3 are supplied to the zero and single inputs of trigger 9, respectively, and the bursts of pulses from coincidence circuits 4 and 5 to the zero and single inputs of trigger 10. From the outputs of trigger 9, the square-phase signals with differential frequency arrive at output schemes of coincidence 7 and 8. A square-shaped signal from the trigger 10 is fed to shaper 1, from which pulses come

I to the other inputs of the output circuits of coincidence 7 and 8. The coincidence of the moment of arrival of the pulse of the former 11 with the resolving potential of the rectangular signals

the shape of the trigger 9 occurs only on one of the output schemes of coincidence 7 or 8. If the frequency of the input signal is higher than the frequency of the reference signal, then this coincidence occurs in scheme 7, the output

of which pulses of difference frequency appear. If the frequency of the input signal is lower than the frequency of the reference signal, then the pulses of the difference frequency appear at the output of the circuit.

Prev W et vi {3 o 6. p e shadow

The frequency detector | e containing the shaper of the input signal, the output of which is connected to four coincidence circuits, the shaper of the reference signal with four outputs, the signals of which are phase-shifted by O, 18 O, 90 and 27 O °. „Ol- connected, respectively, to the second inputs of the coincidence circuits, and the determinant of the sign of the difference frequency, made in the form of two output coincidence circuits, which is

increase detection accuracy over a wide frequency range, it is equipped with two triggers and a differential frequency pulse shaper, the zero and single inputs of the first trigger are connected to the outputs of the first and second coincidence circuits respectively, and the zero and single inputs of the second trigger are connected to the outputs of the third and fourth matching circuits, while the outputs of the first trigger are connected to one of the inputs of the output matching circuits, the second inputs of which are connected to the output of the second trigger through a pulse former in.