Device for measuring the average value of pulse signals

DETAILED DESCRIPTION OF THE PRESENT FIG.
5 illustrates an embodiment of the present invention, in which the parts corresponding to those in FIG.
1 are identified by the same reference numerals.
The construction from the input terminal 11 to the linear detector 17 is identical with the construction of FIG.
1 and follows the rules of the Comite International Special des Perturbations Radioelectriques (CISPR).
In this embodiment the output of the linear detector 17 is fed to a low-pass filter 31 composed of passive elements alone.
The low-pass-filter 31 is made up of, for example, resistance elements and capacitance elements, and its cut-off frequency is set to tens of kilohertz, tens of milliseconds in terms of time constant.
Hence, as shown in FIG.
2, the detected output pulse 23 in FIG.
2B is slightly integrated by the low-pass filter 31 and, as a result, becomes an isolated wave output 32 of a dull waveform with a small peak value and an enlarged pulse width as depicted in FIG.
2D.
The isolated wave output 32 is sampled by an A-D converter 33 with a period Ts, and respective sample value V.
sub.
1, V.
sub.
2, .
.
.
are converted to digital values, which are provided to an arithmetic circuit 34.
That is, pieces of sampled data of one frame T.
sub.
f at N points, for instance, 700 points are fed to the arithmetic circuit, wherein an average value is calculated; namely, (V.
sub.
1 +V.
sub.
2 +V.
sub.
3 +.
.
.
+V.
sub.
n)/n is calculated.
In other words, a value obtained by averaging the areas of respective isolated wave outputs 32 in one frame T.
sub.
f is obtained as an average value A.
The peak value of the isolated wave output 32 is not small relative to the peak value of the impulsive noise 22 and is appreciably larger than the noise level, and the area of the waveform can be measured with accuracy.
Since the peak value of the isolated wave output 32 is relatively large, the peak value can be lowered, by adjusting the variable attenuator, to such an extent that the frequency converter 13 and the intermediate-frequency amplifier 15 are not saturated by the impulsive noise 22, and even if the impulsive noise 22 is short and the period T