SU1706050A1 - Device for forming frequency-shift signals - Google Patents

Abstract

The invention relates to radio engineering and can be used to obtain frequency mannpudated signals. The purpose of the invention is to increase the formation accuracy by reducing the instantaneous frequency emissions. A device for generating frequency-telegraph signals comprises a frequency shift generator 1, an electronic switch 2. a pulse shaper 3, a one-shot 4, a delay line 5. B-flip-flop 6, element OR 7. frequency divider 8 and output matching unit 9. The device allows to significantly reduce the instantaneous frequency emissions, depending on the set shift, which leads to a proportional decrease in the width of the spectrum of out-of-band emissions and telegraph distortion in the signal 2 or

Description

The invention relates to radio engineering and can be used to obtain frequency-manipulated signals.

The purpose of the invention is to increase the formation accuracy by reducing the instantaneous frequency emissions.

FIG. 1 shows a structural electrical circuit of the proposed device; in fig. 2 - time diagram.

The device for generating frequency-telegraph signals includes frequency shift generators 1, electronic switch 2, pulse shaper 3, one-shot 4, delay line 5, D-flip-flop 6, element OR 7, frequency divider 8, and output matching unit 9.

The device works as follows.

Frequency shift generators 1, the number of which should be equal to two to form the THB signals, and four for the DPT, produce high-frequency oscillations that are shifted in frequency by the intervals L A /, where N is the frequency division factor in

divider 8, L / - required frequency shift in adjacent information symbols of the output frequency-telegraph signal. Moreover, the value of A / meets the condition / «, / I, where / and is the average value of the frequency of the shift generators.

In the electronic switch 2, the sinusoidal oscillations of the shift generators 1 are converted into a pulse voltage of a selected logic level with the same repetition frequency, and then, by control commands from an external source (not shown), the manipulation signal is switched to the output switch 2 The 3 pulse generator is not a necessary element if the output signals of the I shift generators are pulsed.

At the moments of switching the shift generators 1, having different frequencies, the duration of the pulses or intervals between the pulses at the output of the switch 2 can be drastically reduced. This is shown in

one

About O5 About SP

waveform (Fig. 2, a). The resulting shortened "quasi-oscillation periods" cause a sharp increase in the instantaneous frequency and, therefore, a broadening of the spectrum of out-of-band emissions.

The 3 pulse generator, which can be performed by delaying, inverting and logical multiplying the delayed and non-delayed signals on the AND-NICs, selects the front of each pulse (Fig. 2, b) entering its input from the switch 2 output. The single-oscillator 4 starts with each pulse from the output of the imaging unit 3 pulses and produces rectangular pulses, the duration TI of which is slightly less than half the period of 7m repetition, that is, meets the CONDITION

.,.

Where

r “b

As a result, at the output of the one-shot 4, the pulse sequence is transformed so that short pulses are turned into short pauses (Fig. 2, c). Such reversal is achieved due to the additional delay of the moment of changing the information symbol by half the pulse repetition period. In the opinion that the manipulation period is much longer than the repetition period that is performed in real devices, the resulting delay does not introduce distortion in the modulating function.

The generated pulse signal by ci iiaei to the input of delay line 5 and to the synchronization input of D-flip-flop 6. The delay / j of signals in delay line 5 should be equal to half the average value of the pulse repetition period, i.e.

Гп.

The output of the spike n delay pulse sequence (Fig. 2, d) is fed to the information input of the D-trig ra 1. Then, taking into account the conditions t and d: --- 2 # - Lt, entry c) -grigger 6 logical units only occurs at the front of the pulse following a short pause. All other edges of the pulses arriving at the synchronization input of the D-flip-flop 6. write a logical zero into it (Fig. 2, d). As a result, when a short pause appears in the sequence, a pulse signal is formed at the output of the / -trigger (Fig. 2, e), the length of which is 7m, satisfies the condition .g, and the temporal position coincides with the position of the short pause in the pulse sequence at the output of the line 5 delay.

0

five

five

0

0

five

0

five

When a logical addition of the signal received at the output of the D-flip-flop 6 and the delayed delay line 5 of the pulse sequence, a signal is generated at the output of the element 7 (Fig. 2, e). This signal has no short pulses or pauses, and the quasi-period of pulse repetition when switching the shift generators 1 becomes greater than or equal to 7 and. As a result of such inhibition of the time of frequency change in the THF or HPT signal, the emission level of the instantaneous frequency decreases and, consequently, the width of the spectrum of out-of-band emissions decreases.

A pulse frequency divider 8 having a division factor L, causes the frequency of the signal and the shift L / frequency to the desired value. The need to install the divider 8 is also explained by the fact that it allows you to increase L times the frequency of the reference oscillations in the rings of the PLL of the shift generators 1 and thereby increase the speed of the ring and at the same time reduce the level of non-harmonic components of the output signal spectrum.

The output matching unit 9 is intended to transfer the frequency-telegraph modulation to an output signal having a fixed frequency or varying in the frequency range. As block 9, for example, a heterodyne frequency converter or a synchronized generator covered by a PLL ring can be used, in which the frequency-telegraph signal obtained at the output of frequency divider 3 is used as a reference signal.

Claims (1)

Invention Formula A device for generating frequency-telegraph signals containing frequency shift generators, the outputs of which are connected to the signal inputs of an electronic switch, an OR element whose output through a frequency divider is connected to the input of the output matching unit whose output is the output of the device whose control input is The control input of the electronic switch, characterized in that, in order to increase the formation accuracy by reducing the instantaneous frequency emissions, a D-trigger is introduced and the pulse shaper, the one-oscillator and the delay line, the output of which is connected to the D input of the D-flip-flop and to the first input of the OR element, the second input of which is connected to the output of the D-flip-flop (its input is connected to the output of the single-vibrator, the output of the electronic switch is connected to the input of the pulse former. I I, I l-ini:; i I. w / y is: .Ч | J I IH II11 v.VI r, 11 PGGN, / i lMH I.irnUi Hod I I G. 4.JH} / I HU.HJIV (. S fH. II , I 1 i i I) IH II .-. .i1 i UN ..i ii; .. I: .nbj ii and ii CLUIIIM. h about i. iHH.MiJ..I ll; / .ID | І1ИПИ .ch) н.ч П1: о | Ki: dn 0 i ildoiM1); ili iM.i kS v) h, 1. d.1) Vl.nix.ij Ц1 чл г. г4 Ц Jo.ixni -if 1l inV.J () li.Mi. lll.:..-1 | J and runun 9 2 2 / / 7