Method and arrangement for the determination of the ratio for common-channel or adjacent-channel interferers in digital mobile communication networks

Apparatus for determining the signal to noise (C/I) ratio for common-channel and adjacent-channel interferers in a digital mobile communication network, comprising:

• a receiver antenna for receiving a signal having a wanted signal s(t) and a noise signal i(t);
• a measuring receiver connected to the antenna output for subjecting the received signal to an envelope demodulation and producing an envelope function output signal R(t);
• an analog/digital converter interfaced with the measuring receiver for sampling the envelope function output signal of the measuring receiver in selected time intervals of .DELTA.T during a defined measurement time T.sub.ges ;
• a computer connected to the output of the analog/digital converter for receiving the sampling values from the converter, whereby N pairs of sampling values of the envelope function R(t) are digitized and stored at times ti and ti+.DELTA.T, where i=1-N, as a consecutive sequence of 1-N of the square of the envelope function R.sup.2 (t);
• the computer further comprising means for generating auxiliary values X' and Y' from the stored 1-N values of the square of the envelope function, the auxiliary value X' being determined by adding up the 1-N individual squares and dividing the sum by N, and the auxiliary value Y' being determined by first computing the N differences of the sampling values of the envelope function at time intervals .DELTA.T, squaring the differences, adding up the total of the squared differences, and dividing by N;
• means for applying a correction factor k so that the value Y' is corrected to value Y which is proportional to four times the product of the individual powers of the wanted signal s(t) and the noise signal i(t);
• and
• means for determining the signal to noise ratio C/I from the following relationship:
• ##EQU12## where X'=X and ##EQU13##