SU450108A1 - Analog wideband frequency meter - Google Patents

Description

(54) ANALOG WIDE BAND METER

FREQUENCIES

fermentation to receive the signal, depending on frequency - V (t) (Wo) cos att.

At the same time, in order to eliminate the influence of the instability of the amplitude of the signal on the measurement error, it is necessary to ensure the constancy of the amplitude of the signal from the sensor, for example, by using amplifiers with automatic gain control.

The drawing shows a block diagram of the described meter, consisting of a differentiating device 1, a generator of 2 rectangular pulses, a logarithmic frequency meter 3 and a switching circuit 4.

The switching circuit 4 consists of a Schmitt trigger 5 and two keys 6 and 7. A differential device can be implemented from a conventional differentiating / C-chain and a full-wave rectifier.

The device works as follows.

The measured signals are fed to the diffusing device 1, which acts as a linear low frequency meter, and simultaneously to the driver 2, which converts the input sinusoidal signals to square signals. A Schmitt trigger can be used to form the near-coal signals. The signals generated by shaper 2 are fed to a capacitor frequency meter 3. The signals from the output of the capacitor frequency meter 3 and the differentiator are combined using a switching circuit 4.

The switching circuit 4, controlled by a signal from the output of the frequency meter or from the output of the differentiating device, serves to automatically connect a capacitor frequency meter and a differentiating device to the output of the meter. This is accomplished by interrupting the signals from blocks 4 and 1 with the help of keys 6 and 7, controlled by a Schmitt trigger 5.

In the differentiator, the C-depochka serves to receive a signal of the form () co5o), and a full-wave rectifier - to select the amplitude of this signal (Waos).

At low frequencies of the input signal, the measurement is carried out by the differentiator 1, and the signal from it through the switching circuit 4 is fed to the output of the meter, and the signals from the frequency meter 3 are blocked by the switching circuit 4.

The switching circuit 4 changes its state, interrupts the signal from the output of the trimmer 1, and connects the output signal from the frequency meter 3 to the output when the control signal of the circuit exceeds the threshold value. In this case, the conversion of the frequency of the input signal into a voltage occurs as follows: square signals are generated from quasi-periodic input signals, the frequency of which is converted by frequency meter 3 to the output signal supplied through switching circuit 4 to the output of the speed meter.

At a frequency, the switching circuit disconnects the signal from the frequency meter output and connects a differentiating device to the output.

Subject invention

Claims (2)

1. Analog wideband frequency meter containing series-connected rectangular pulse shaper and a capacitor frequency meter, characterized in that, in order to improve the speed of the meter over the entire measurement range and improve the accuracy in measuring low frequencies, it is equipped with a differentiating device and switching circuit, one the input of the switching circuit is connected to the output of a capacitor frequency meter, and the second is connected to the output of a differentiating device, the input of which is connected to the input Forming rectangular pulses. 2. The frequency meter according to claim 1, characterized in that for automatically connecting the differentiator, the switching circuit comprises a Schmitt trigger and two keys, wherein the Schmitt trigger input is connected to the first input of the first key, and its outputs are connected respectively to the second inputs of the first and second keys. entrance about e O-1 6 1-1 I recalled ejrena