SU570975A1 - Frequency discriminator - Google Patents

Description

one

The invention relates to radio engineering and automation and can be used in frequency systems for remote control, telemetry and other electronic devices that require tuning to a specific fixed frequency.

Frequency discriminators sampling a predetermined frequency are known 1, 2, 3. The closest technical solution to this is a pulse selection circuit containing a pulse shaper from a harmonic signal, a delay node and an AND 3 circuit.

However, this circuit has a low frequency resolution and responds to multiple frequencies.

The purpose of the invention is to increase the resolution of the circuit.

This is achieved in that the circuit comprises a frequency-dependent phase-shifting device connected in series, for example a circuit connected to the discriminator input, and an additional pulse shaper, the output of which is connected to the second input of the coincidence circuit.

In the drawing, an electrical schematic diagram of a discrete frequency signal selector is shown, based on a predlozhenny frequency discriminator.

The frequency discriminator contains two channels connected to the common input of the device.

The nerve channel consists of a pulse former 1 and a delay unit 2 connected in series with it. The outputs of the delay node 2 are connected to one input of the coincidence circuit 3.

The second channel contains a frequency-dependent phase shifter 4 with a steep phase characteristic, in which both active and passive LC or C circuits can be used, the output of which is connected to the second input of the matching circuit 3 via an additional driver 5.

Consider the operation of the device in steady state.

A harmonic signal with a frequency / k from the discriminator input is simultaneously applied to the pulse shaper 1 and to the frequency dependent phase shifter 4.

The pulses formed by shaper 1 and rigidly attached to a certain phase of the original harmonic signal (moments of zero crossing in the positive direction) are fed to node 2 delays, from the output of which to the input of circuit 3 coincidence pulses will be received with frequency and.

A pulse formed by an additional driver 5 of a harmonic signal / k transmitted through phase shifter 4 and received as a result of this time shift relative to the original signal by an amount proportional to the frequency deviation of the signal from the resonant frequency of the device 4.

At a certain frequency value, the signals from both channels simultaneously arrive at both inputs of the coincidence circuit 3, at the output of which there are coincidence pulses in the MS.

In this way, a certain frequency in the device is discriminated against.

The device is converted into a discrete frequency signal selector, if the delay node is executed as a time interval sensor, which can be used by any known distribution scheme, for example, a chain of included relaxers with one steady state, triggering each other, or a delay line with taps. The outputs of the sensor 2 time intervals are then connected to the separate inputs of the groups of the matching circuit 3, the second inputs of which receive signals from the additional imaging unit 5.

Thus, the first inputs of the 3 matches will consistently receive pulses with a frequency / k, with a delay independent of the frequency of the transient signal, and determined only by the sensor parameters of 2 time intervals and the retraction number, and the second combined inputs Circuit 3 matches pulses that receive a certain time shift relative to the original signal by an amount proportional to the frequency deviation of the signal from the resonant frequency. At the same time, the K-coincidence circuit generates a pulse sequence with frequency / k.

This pulse sequence is fed to the input of the K-th storage device 6, the output of which is only

after multiple pre-calculated pulses at its input, which eliminates false positives during the transient period and increases the selector resistance to impulse noise.

The signal from the output of the K-th storage device is fed to the input of the K-th output device 7, causing it to trigger, and this is fixed by the presence of the selector at the input

signal with frequency / k.

Thus, the presence of a frequency-dependent phase-effecting device with a steep phase characteristic in the circuit leads to an increase in the frequency resolution of the circuit and excludes the possibility of triggering at multiple frequencies, but, on the other hand, increases the transient time, which leads to can be avoided by connecting output devices to coincidence circuits through storage devices, which simultaneously increases the noise immunity of the circuit.

Claims (3)

1. USSR author's certificate №363927, cl. G 01R 23/00, 1973. 2. USSR author's certificate No. 396811, cl. H 03 D 3/02, 1973. 3. Firestone Pulse selection scheme for selecting frequency channels. - “Electronics, 1963, No. 51, p. 23-24.