SU767955A1 - Reference frequency oscillator - Google Patents

Description

(54) BASIC FREQUENCY GENERATOR

one

The invention relates to a pulse technique and can be used in phase shift keying information transmission systems.

A device is known comprising two counters, a block of coincidence elements, a decoder, two frequency dividers, a reference frequency generator, triggers, and AND and OR elements.

However, this device is quite complex and does not provide sufficient accuracy of frequency tuning.

The aim of the invention is to improve the accuracy of the frequency control.

This is achieved by the fact that the reference frequency generator, which contains two pulse counters, the outputs of which are respectively connected to the inputs of the coincidence unit block, a crystal oscillator, a frequency divider, a trigger, an AND element, a short pulse shaper, two AND elements and a shift register, turns through which the first additional element I is connected to the input of the short pulse pulse former and to the first inputs of the main and second additional elements I, the second inputs of which are connected to the output of quartz The generator, the output of the second additional element I is connected to the first input of the first pulse counter, the output of the main element I and is connected via a frequency divider to the first input of the second pulse counter, the output of the block of elements of coincidence is connected to the second input of the first pulse counter and to the first input of the trigger, the second input of which is connected to the output of the short pulse generator, with the second inputs of the frequency divider and the second pulse counter and with the third input of the first pulse counter.

FIG. 1 shows a functional diagram of the proposed reference frequency generator; in fig. 2 oh time diagrams.

15

The reference frequency generator includes a crystal oscillator 1, a shift register 2, elements AND 3, 4, 5, frequency divider 6, a short pulse driver 7, counters 8, 9 pulses, a block 10 of coincidence elements 20, and a trigger 11. In FIG. 1 also shows the input and output tires 12 and 13.

The generator works as follows.

Claims (2)

A busbar 12 receives a synchronization signal through a receiving device (not shown), which is a sending of sinusoidal voltage with a period T (Fig. 2, a) or a series of rectangular pulses with distorted edges and cuts. A receiving device converts this signal into square-shaped clock pulses with an error, so that the time between the edges of these pulses is T + AT (Fig. 2, b). The clock pulses are applied to the input of register 2, which is reset to the initial state before trimming. When the first clock pulse arrives at the input of the register 2, its element 2 1 is recorded 1 and remains until the register is cleared (Fig. 2, c), therefore 1 input of element 3 comes 1, while the other input of this circuit also acts 1, removed from the inverse output of the last element of the 2nd reg. 2. Thus, at the output of element 3, a control pulse arises (Fig. 2, h). Further, the state of the inputs of the AND 3 element does not change, it is only with the arrival of the nth pulse that input 1 to the second input of the AND element 3 stops and the formation of the control pulse ends, the duration of which, taking into account the possible error, is (n-1) T + AT. Thereafter, register 2 returns to its initial state after the end of the synchronizing signal. Under the action of the front of the control pulse, the driver 7 (Fig. 2, and) resets the divider 6, the counters 8, 9, and the trigger 11 (the beginning of the adjustment). At the same time, at the first input of the element And 5 acts "1, but due to the fact that this input is inverse, i.e. At this input, "1" is inverted into "O, and element 5 is closed, and the flow of counting pulses from generator 1 to counter 9 stops (Fig. 2, k). The first input of AND 4 is direct, i.e. the input signal is not inverted, therefore the element 4 is opened for the whole time of the control impulse, and the counting pulses are fed to the input of the divider 6 (Fig. 2, l), which divides by 2 (p-1). Thus, during the duration of the control pulse, the counter 8 will register the value of the half-period duration (T / 2) + AT / 2 (P1), which corresponds to the value of the period duration T-f АТ / (п-1), i.e. this ensures a reduction in the error of the adjustment in (n-1) times. After the termination of the control pulse, the And 4 element is closed, and the And 5 element opens, as a result of which the counter 9 begins to perceive the counting pulses of the generator 1 (Fig. 2, k). If the numbers recorded in the counters 8 and 9, i.e. After half a period at the output of block 10, a pulse is formed (Fig. 2, n), changing the state of trigger 11 (Fig. 2, o) and bringing the counter 9 to the zero state. Next, the pa6otaeT counter 9 is similarly, and at the output of the trigger 11, rectangular oscillations with the frequency of the synchronizing signal are created. The duration of the half period is actually found as the arithmetic average (n-1) of the period values. The proposed reference frequency generator increases the accuracy of the frequency adjustment by obtaining the information by averaging the n period values; its use improves the accuracy of deciphering the phase-shifted signals. Claims A reference frequency generator comprising two pulse counters, the outputs of which are connected to the corresponding inputs of a block of matching elements, a crystal oscillator, a frequency divider, a trigger, an AND element, characterized in that, in order to improve the accuracy of the frequency control, a shaper is additionally introduced pulse, two elements And and the shift register, the outputs of which through the first additional element And are connected to the input of the short pulse shaper and to the first inputs of the main and second complementary And the second inputs of which are connected to the output of the quartz oscillator, the output of the second additional element And connected to the first input of the first pulse counter, the output of the main element And connected through a frequency divider to the first input of the second pulse counter, the output of the matching elements connected to the second input of the first pulse counter and the first input of the trigger, the second input of which is connected to the output of the short pulse generator, with the second inputs of the frequency divider and the second pulse counter and the third input of the first pulse counter. de g (+ yy