SU995337A1 - Generator - Google Patents

Description

one

The invention relates to radio engineering and can be used in frequency stabilization devices.

Generators comprising a controlled generator, a thermal sensor, a code converter and a digital-to-analog converter are known. The temperature sensor detects the ambient temperature and, in the form of a digital code, provides the measured value to the input of the code converter. The code converter stores the shape of the temperature-frequency characteristic (TFC) of a quartz resonator of a controlled oscillator. At the output of the code converter, a code of the compensating function is formed, which with the help of a digital-to-analog converter is converted into a control voltage applied to the input of the controlled generator 1).

However, these generators have a low stability of the oscillation frequency, since they do not take into account the temperature-dynamic phenomena in quartz resonators.

A generator is also known that contains a thermal sensor and is connected in series (54). GENERATOR

the reference oscillator, the mixer, the first low-pass filter, the phase detector, the second low-pass filter, the amplifier and the controlled oscillator, the output of which is connected to the input of a frequency divider, the second

5 input mixer and divider input with a variable division factor, the output of which is connected to another input of the phase detector, as well as the first code converter, the output of which is connected to

Q is the control input of the divider with a variable division factor, and a counter, the input of which is connected to the output of the thermal sensor.

Thermal compensation is carried out by changing the division factor of the frequency divider with a variable division factor. The division coefficients are determined experimentally for each temperature point in the working temperature range when tuning the generator and stored in code converter 2.

However, the known generator does not take into account the temperature-dynamic phenomena in the quartz resonator of the reference generator with sudden changes in the ambient temperature, which reduces the stability of the output oscillation frequency.

The purpose of the invention is to increase the frequency stability during unsteady thermal effects.

To achieve this goal, a generator containing a thermal sensor and a series-connected reference generator, a mixer, a first low-pass filter, a phase detector, a second low-pass filter, an amplifier, and a controlled oscillator whose output is connected to the input of the first frequency divider. The second input of the mixer and the input of a divider with a variable division coefficient, the output of which is connected to another input of the phase detector, as well as the first code converter, the output of which is connected to the control input of the divider with a variable division ratio, and a counter, the input of which is connected to the output of the thermal sensor, between the output of the counter and the input of the first code converter are the serially connected switch, the second code converter and the adder, and the second frequency divider, whose input is connected It is connected to the output of the first frequency divider, the second output of the switch is connected to the second input of the adder, and the counter is made in the form of a reversible counter, the first and second control inputs of which are connected to the npjfMbiM and inverse outputs of the second frequency divider, respectively.

The drawing shows a structural electrical circuit of the proposed generator.

The generator contains a reference generator 1, a thermal sensor 2, a mixer 3, a first low-pass filter 4, a phase detector 5, a second low-pass filter 6, an amplifier 7, a controlled oscillator 8, a divider with a variable division factor (DDC) 9, a counter 10, the first the converter 11 codes, the first frequency divider 12, the switch 13, the second converter code 14, the adder 15, the second frequency divider 16.

The generator works as follows.

The oscillation frequencies of the reference oscillator 1 and the controlled oscillator 8 are mixed in the mixer 3. The first filter 4 separates their difference frequency, which is fed to the first input of the phase detector 5. The second input of the phase detector 5 receives the N frequency divided NDCK 9 oscillator 8. The signal from the output of the phase detector 5 is filtered by the second filter 6 and through the amplifier 7 changes the frequencies of the controlled oscillator 8 until the unbalance signal is zero.

The division factor N of the DPCD 9 is chosen such that

fon (t)

out

where ln ()

the frequency of the reference oscillator 1, depending on the temperature;

OUT - output frequency of the controlled oscillator 8.

The output frequency of the sensor 2 is fed to the input of the counter 10. The time interval during which the

pulse counting from the output of the temperature sensor 2 is formed from the output oscillations of the controlled generator 8 using the first frequency divider 12 and the second frequency divider 16. The counter 10 is made in the form of a reversible counter. If the division divider factor 12 is equal to M, then during the time M / fgb,; p, a high potential is present at the input of the counter 10 and the counter 10 operates in the mode of summing the pulses from the output of the thermal sensor 2 to its signal input.

During the next time interval, the input of the subtraction counter 10 has a high potential and a counter

10 operates in a subtraction mode for incoming pulses. The second frequency divider 16 serves to form a symmetrical time interval for addition and subtraction. After the end of the summation, a code corresponding to the ambient temperature is stored in the counter 10. After the completion of the subtraction, in the counter 10 there remains a code corresponding to the difference of the temperature codes between the measurement in the addition mode and the subtraction mode, i.e., the value is proportional to the rate of temperature change. After the end of the summing operation, the value recorded in the counter 10 is transmitted to the first input of the adder 15 and stored in its memory cells. After the completion of the subtraction operation, the difference value is supplied via the switch 13 to the second converter 14 of codes, which forms an amendment to the compensating function determined by the rate of temperature change. This correction is applied to the second input of the adder 15. With the arrival of the code combination to the second input of the adder 15, the sum of the values fed to its first and second inputs is transmitted to the input of the first converter

11 codes, which determines the division ratio of the DPCD 9.

The required division factors at various temperatures and rates of temperature change are determined experimentally during generator tuning. If the temperature between the two samples has not changed, then the second converter 14 of the codes produces a zero correction, and the division ratio of the PDKD 9 does not differ from the division ratio determined when the generator is tuned to under conditions of a slow change in temperature.

Claims (2)

Thus, the proposed device has improved dynamic characteristics, since it takes into account the rate of change of temperature, which allows reducing the time for setting the output frequency of the generator with abrupt changes in ambient temperature and stability during non-stationary thermal effects. The invention includes a generator containing a thermal sensor and a series-connected reference oscillator, a mixer, a first low-pass filter, a phase detector, a second low-pass filter, an amplifier and a controlled oscillator whose output is connected to the input of the first frequency divider, the second mixer input and the divider input variable division factor, the output of which is connected to another input of the phase detector, as well as the first code converter, the output of which is connected to the control input of a divider with variable coefficient The division circuit and the counter, whose input is connected to the output of the thermal sensor, differing well that, in order to increase the frequency stability during non-stationary thermal effects, serially connected switch, second code converter and adder, as well as, are entered between the counter output and the input of the first code converter. A second frequency divider, the input of which is connected to the output of the first frequency divider, is introduced, the second output of the switch is connected to the second input of the adder, and the counter is designed as reversing A first counter, the first and second control inputs of which are connected respectively to the direct and inverse outputs of the second frequency divider. Sources of information taken into account in the examination 1. Prak and others. The system of temperature compensation of frequency drift based on digital integrated circuits for master oscillators. “Electronics, 1972, No. 17, p. 63-66. 2.Warwic G. A digital technique for temperature compensation of crystal oscillators. “Proc. Conf. Radio Receivers and Assoc Syst Southampton. London, 1978, 207-216 (prototype).