SU559369A1 - Next filter - Google Patents

Description

one

The invention relates to radio engineering and can be used in systems for extracting a quasi-harmonic signal from noise.

The following filter is known, made on the basis of rings of phase-locked loop and containing signal limiters, automatic control circuits.

However, it spends significant

time to join synchronicity.

The closest technical solution to the invention is a servo filter comprising a filtering unit connected in series and a phase locked loop with a tunable output generator.

This filter also has the above disadvantage.

According to the invention, the reduction of the tracking filter time is achieved by the fact that in it the input source is connected to the filtering input of the filter through an adder, the second input of which is connected to the output of

The oscillator is connected via a sequentially connected phase shifter and key, and the control input of the adjustable oscillator is connected via a threshold element to the output of the filtering unit.

The drawing shows the block diagram of the proposed following filter.

The following filter contains in series the filtering unit 1 connected to the source 2 of the input signal via the adder 3, and the ring 4 of the phase-locked loop with a tunable generator 5 at the output. The second input of the adder 3 is connected to the output of the adjustable generator 5 via a serially connected phase shifter 6 and a switch 7, the control input of the adjustable generator 5 through the threshold element 8 is connected to the output of the filtering unit 1.

The device works as follows.

Claims (1)

The threshold element 8 is set to the minimum signal level for the operation of the ring 4 phase-locked loop. Phaser 6 has a phase cross-linking of 1t / 2 in total with a phase shift, generated by key 7, an adder-CH and a filtering unit 1, which provides the most accurate tracking of the frequency. If there is an input signal exceeding the threshold of the threshold element 8, the key 7 opens. The following filter acts as a common phase locked loop. When the input signal level drops below the threshold or when it is lost, the horny element B closes key 7. The output signal of the adjustable oscillator 5 is fed through phase shifter 6 to input of adder 3 and then through filtering unit 1 to input of ring 4 of phase-locked loop. As a result, the latter is transferred to the auto capture mode, i.e. The tuner 5 is tuned to its own signal passing through filtering block 1 and maintains the frequency near the center of the passband of filtering unit 1 until a sufficiently high level input signal is received. Due to the fact that the frequency of the tunable oscillator is constantly maintained in the vicinity of the bandwidth center of filtering unit 1, the time taken for the next filter to be synchronized significantly decreases. Claims The following filter contains a filtering unit connected in series: and a phase locked loop with an adjustable oscillator output, characterized in that, in order to reduce synchronization time, the input source is connected to the input of the filtering unit through an adder, the second input of which connected to the output of the adjustable oscillator through a series-connected phase shifter and key, and the control input of the adjustable oscillator through the threshold element is connected to you ode filtration unit.