SU466601A2 - Device for automatic frequency control of pulsed magnetron oscillators - Google Patents

Description

one

The invention relates to radio engineering, can be applied mainly in transmitting microwave devices.

A device for automatically adjusting the frequency of a pulsed magnetron oscillator (ed. St. No. 272386), containing an external source of a microwave synchronizing signal, a circulator, a synchronizable tunable pulsed magnetron, a phase detector, a frequency detector, an amplitude selector, a paraphase amplifier, two peak detectors, a differential direct current amplifier, magnetic amplifier, frequency tuning mechanism of a magnetron with a reversible electric motor and a tachometric feedback circuit.

The known device does not operate stably enough when synchronizing a magnetron from an external source of a microwave synchronizing signal with a coded intrapulse phase shift keying (QFM). This disadvantage is due to the fact that the phase of the microwave synchronization signal (f (t) in the code group changes from a pulse to a pulse for a finite period of time, as a result of which the frequency ω f / d changes, and at the output of the frequency detector tuned to pulses appear in the carrier frequency of the signal. In general, their amplitude may exceed the limiting level of

minimum amplitude selector. The passage of pulses through a selector under these conditions may disrupt the operation of the phase-locked loop, since these pulses may create false information that the magnetron is not operating in synchronous mode.

The purpose of the invention is to increase the stability of the synchronization of the magnetron

microwave signals from CFMF.

The proposed device is characterized in that between the amplitude selector and the adder there are connected in series the coincidence circuits, the second input of which is connected to the additionally introduced strobe pulse generator, and the waiting rectangular pulse generator.

The drawing shows a block diagram of the device.

The device contains a source of microwave synchronizing signal with CFMF 1, circulator 2, tunable pulsed magnetron 3, phase detector 4, frequency detector 5 (type of notch filter), amplitude selector 6, adder 7 with two inputs, paraphase amplifier 8, peak detectors 9, 10, DC differential amplifier 11, magnetic amplifier 12, frequency tuning mechanism 13

a magnetron with a reversible electric motor; a tachometric feedback circuit 14 for improving dynamic stability; a matching circuit 15; a waiting square pulse generator 16; and a strobe pulse generator 17.

The microwave synchronizing signal with CFMF and carrier frequency sos from source 1 through circulator 2 is fed to magnetron 3, having a frequency of free self-oscillations co, close to (OC, so | ci) c - ((O, where Dsho is the sync band. Signals The microwave from source 1 and magnetron 3 enters the phase detector 4 and then to the first input of the adder 7. Outside the synchronization band (its boundaries (a and co, and the center coincides with (OC), beats occur with frequency | (OC - (o. In the synchronous mode of operation of the magnetron, when (OC-soo | A (OC, signal from the phase detector Uff through a paraphase amplifier 8, peak detectors 9, 10 and differential amplifier 11 to the input of magnetic amplifier 12, provides the error signal, the sign and magnitude of which are determined by the sign and magnitude of the phase shift caused by the "potential detuning Fc- (o- These factors determine the direction and speed of rotation of the electric motor in the tuning mechanism 13, with which the frequency adjustment of free auto-oscillations (Oo of the magnetron 3) is achieved. This ensures the closure of the phase-locked loop ( AP) and maintain the frequency difference bs-NEO close to zero.

However, the PLL circuit does not provide self-tuning in cases where the frequency of the co magnetron is outside the sync band of the ASC. In fact, due to the beep, the error signal is zero, since the amplitudes of the positive and negative half-waves are the same.

A frequency locked loop (CHAP) is used to provide self-tuning. A signal from a frequency detector (in the form of a notch filter) 5 tuned to a frequency (OC enters an amplitude selector (for example, a semiconductor diode) 6. The selector passes 15 signals / chd to the first input of the coincidence circuit, the amplitude of which exceeds a certain level Un, t i.e. f / 4fl f / n. As a result, the dependence of the output voltage f / ac of the selector 6 has the shape of a deformed resonance curve with a flat bottom and steep slopes, with the bottom

(when Ua.) is located within the synchronization band Atoc In the beat mode, when | (0s - () s, chd Un- Vac pulses go to the first 5 input of the coincidence circuit 15, and f / cip strobe pulses from the generator 17 are fed to its second input. These strobe pulses coincide in time with the first signs of the CFMF signal.If both pulses coincide in time, circuit 10 coincides 15 produces a pulse that triggers the waiting square pulse generator 16. Its output pulses U receive the second input of the adder 7. As a result, the error signal on 15 magnetic inlet amplifier 12 is not zero due to the fact that the positive half waves t / fd are added to the pulses U. The reversible motor of mechanism 13 begins to tune the frequency (Oo of the magnetron .3, for example, upwards to the lower border from the synchronization band. When the sync band, t / bh becomes less than f / n, ao becomes zero due to the action of the amplitude selector 6; the pulses at the output of the coincidence circuit 15 and the output of the waiting generator 16 also disappear. The loop of the FAP automatically disconnects and cannot interfere with the operation of the PLL circuit that is in effect at this time. In fact, voltage peaks Idch caused by frequency jumps of the synchronizing microwave signal from CFMF from source 1 at the final time of the phase change from sign to sign , the time does not coincide with the strobe pulses, so the generator 16 does not start. As a result, only the PLL circuit works.

The device can also be used when synchronizing a magnetron with microwave signals with a 0 ppei frequency internal pulse module (by manipulation).

Subject invention

A device for automatic adjustment of the values of pulsed magnetron generators according to ed. St. 272386, characterized in that, in order to increase the stability of operation when synchronizing the magnetron with microwave signals with intrapulse phase shift, between the amplitude selector and

the adder includes a series-connected coincidence circuit, the second input of which is connected to the additionally introduced strobe generator, and a waiting generator of rectangular pulses.