SU530262A1 - Percentage frequency meter - Google Patents

Description

one

The invention relates to electrical measuring equipment and can be used in the construction of instruments for measuring the percentage frequency deviation from the nominal value.

A known digital frequency meter comprising a reference frequency generator, pulse shapers of reference and measured frequencies, keys, a control trigger, a coincidence circuit, and pulse counters of reference and measured frequencies. To improve accuracy, it is equipped with a coincidence divider, the control trigger is made with separate inputs, the first of which is connected to the output of the coincidence circuit and the input of the frequency divider, the second to the output of the frequency divider, and the output to the control inputs of the first and second keys.

However, the frequency counter has insufficient speed.

Also known is the percentage frequency meter G2, in which the period of conversion into active is used to extend the measurement range of the relative frequency deviation from the nominal value

Resistance with the subsequent comparison of constant time dB tsDS-chains, one of which includes the specified resistance. In this case, the value of the relative frequency deviation from the nominal value is determined by the number of generator pulses of the reference frequency, which fill the time interval equal to the difference of the time constant specified. R With-chains.

The indicated frequency meter has a pulse shaper, a control unit, a key, an exemplary frequency generator, a period-resistance converter, which forms a string with capacitor C RC whose time constant is compared with the time constant of an exemplary RC chain consisting of T} and CQ, two comparison blocks, a trigger, a BM generator, an active voltage divider, a key and a counter.

The low speed of such a frequency meter is associated with the sequential execution of the operation of converting the period of the measured frequency into resistance followed by the determination of the time difference between the two RC chains, the purpose of the invention is to increase the speed of the percentage frequency meter. This is achieved by the fact that the proposed frequency meter is connected in series by a controlled power source, a measuring bridge, a recording unit as well as a source of reference voltage, the output of which is connected to the first input of the comparison unit, the second input of the latter is connected to the second output of the measuring bridge, and its output the input of the controlled power source, the second input of the measuring bridge is connected to the output of the period-resistance converter. The drawing shows a structural diagram of the proposed percentage frequency meter. The percentage frequency meter contains a key 1, a shaper of 2 pulses, a generator of 3 exemplary frequencies, a 4 period-resistance converter, an unbalanced four-shouldered measuring resistive bridge S, a controlled power supply 6; a registration unit 7, a comparison unit 8, a reference voltage source 9. The input signal of the measured weight is fed to the Shaper 2, the pulses of which are controlled by the key 1, which is opened for a time equal to the period of the measured frequency T. Through the open key 1 from the generator 3 to the converter 4 period-resistance pulses of exemplary frequency are received. In the period-resistance converter, the period t value is converted to a resistance value equal to K, R x H resistance of the reference factor; oscillator frequency 3; the value of the measured frequency; output impedance period-impedance converter. The period-resistance converter 4 forms the shoulder of an unbalanced four-arm measuring resistive bridge 5, in which a constant voltage U r is maintained on the reference resistor. The power supply voltage of the bridge is determined by the output signal of the comparison unit 8, in which the voltage U 3 of the source 9 of the reference voltage is compared. voltage with a voltage across the ticket resistor. The voltage across the reference resistor is determined by the expression ET -R from this formula follows PM St With equal resistance of the shoulders of the bridge, between the shoulders formed by the period-resistance converter, and the shoulder formed by the reference resistor, the voltage in the measuring block (voltmeter) 7 avno ,, - and () Out 2, this is based on the expression (2) this formula has id) and in formula (4) the value is matched to get ". Mf fn The expression in brackets represents the relative deviation of the unknown frequency from but minal value. Thus, by the end of the pulse from the imaging unit 2, the voltage proportional to the relative y from the nominal value, i.e. the measurement in the proposed frequency meter occurs within one cycle, while in the known frequency meter this operation takes place in two cycles. The use of new elements — an unbalanced four-arm resistive measuring bridge with a controlled power source, a recording unit, a reference voltage source — shortens the measurement process. of the invention

pulses, a key, a converter, a period-resistance converter, as well as an exemplary frequency generator, the output of which is connected to the second key input, and a comparison unit, characterized in that, in order to increase speed, it is equipped with a series-connected controlled power source, measuring bridge, recording unit as well as the source of the reference voltage, the output of which is connected to the first input of the comparison unit, the second input of the latter is connected to the second output of the measuring bridge, and its output to the input of the controlled source power supply, the second input of the measuring bridge is connected to the output of the transducer period-resistance.

Sources of information taken into account in the examination:

1.Avt. St. USSR № 409149, cl. G01R 23/10, 02.22.72.

2. Avt. St. USSR number ZOO838, Cl. G01 K 23/10, 05/26/69. (prototype).