SU546825A1 - Digital microwave meter - Google Patents

Description

The meter contains axial mixer 1 1 heterodyne 2, frequency meter 3, driver 4 pulses of the end of the transient process, valve 5, additional counter 6, code-converter converter 7, synchronization unit 8, additional mixer 9, reference source 10, low-pass filter 11 , zero-body 12, pulse shaper 13, delay element 14.

The input signal under study is connected to one input of the main mixer 1, the output of the local oscillator 2 is connected to the input of the digital frequency meter 3 and to the input of the driver 4, the output of which is connected to the start input of the digital frequency meter 3 and through the gate 5, an additional counter 6 and the code-voltage converter 7 is connected to the frequency-control input of the local oscillator 2, the output of the latter through the synchronization unit 8 is connected to the frequency-control input of the local oscillator 2 and the additional mixer 9, the second input of which is connected to Exit reference frequency source 10, and output through the low pass filter II, the zero-body 12 and the generator 13 connected to the input imiulsa valve 5 and to the output of the delay element 14.

The device works as follows.

In the initial state, a signal is received at the input of the device whose frequency must be measured. The source 10 of the reference frequencies produces a uniform grid of reference frequencies, the values of which are determined by the values where / r - 1, 2, 3, etc.

To perform a frequency measurement, a start signal is received at the start input of the device, which resets the counter 6 to the zero position, returns the digital frequency meter 3 to the initial state, opens the gate 5 and enters the input of the delay element 14. Having passed the delay element 14, this signal goes through the valve 5 to the counter 6 and puts it into the state "1. Converter 7 code-voltage under the influence of the code received at its input from the counters produces such a voltage, thanks to which the local oscillator 2 produces a frequency fr, close to the frequency I, but somewhat smaller in magnitude.

The low-pass filter 11 triggers the null organ 12, its output in the pulse shaper 13 is converted into a single pulse.

The impulse from the output of the imager 13 through the open valve 5 enters the counter 6 and translates it into the state "2. The code of this number from the output of the counter is applied to the converter 7 of the code-voltage, where a voltage is generated to control the heterodyne 2, which changes the frequency of the local oscillator to a value frj close but less than the second frequency 2/1 from the reference frequency grid. Since the frequencies of the local oscillator 2 and the source of the 10 reference frequencies become different, the synchronization unit 8 starts working again, raising the frequency / y to 2fi. At the time of comparing the frequencies, the null body 12 acts on the imaging unit 13, which sends them next. pulse in the counter 6 and so on.

The process of filling with pulses of the counter 6 stops when a frequency 2 g / g is set at the output of the local oscillator - close to the frequency (/ 1 source of 10 reference frequencies, or when frequency / g approaches the value of //. Under the influence of synchronization unit 8, the difference between the measured the frequency / x and the current frequency of the local oscillator / n will become equal to or smaller than the value of / i. The difference frequency signal fp lx-fr ,, passes through a filter in the output circuits of the mixer, passing signals in the frequency band from 0 to / ь is fed to the digital frequency 3 and shaper 4 and pulse end of the transition process.

After the steady state of the signal with frequency / p forms on the inputs of these elements (this happens after the frequency becomes equal to the frequency // i), driver 4 produces a single pulse arriving at gate 5 and locking it, as well as digital frequency meter 3, which, under the influence of it, begins to measure magnitude / p.

By the end of operation of the digital frequency meter 3, the frequency code / p is written in its counter, and in counter 6, the code of the number i. In the digital frequency counter code converter, the code i is converted into a code of the ifi value, this value is displayed together with the value on the digital display of the frequency meter 3.

If the value of fi is chosen to be 10 to an integer degree, then it is sufficient to highlight the value of / in the high-order digits of the digital display, and in the lower-order digits, the value of fp so that the value of / x is formed on the display.

To measure the value of / x less than fi, after supplying the input device of the signal under study to PA and forming the input of shaper 4 of steady-state mode, shaper 4 starts digital frequency meter 3, which measures frequency / x. This measurement process begins after the start signal of the digital frequency meter is reset to the initial state and the formation has been enabled for the driver 4 to start the measurement.

Claims (2)

1. Ermolov R. S. “Digital frequency meters. Ed. “Energie, L., 1973, p. 11-20. 2. Remez G. A. “Radio measurements, ed. “Svy, M., 1966, fig. 6, 52.