Patent ID: 7978613

Claim:
A method of measuring a degree of degradation imposed on signals transmitted over a communications channel which is carrying a live call from a transmitter to a receiver, said method comprising: at the transmitter: generating a predetermined test signal having deliberately corrupted error checking data; identifying idle periods in voice activity on a live traffic channel during said live call in which no voice information content is required to be transmitted over the communications channel; in one or more of the identified idle periods, transmitting the predetermined test signal in one or more respective parts over the communications channel from the transmitter to the receiver; at the receiver: identifying the predetermined test signal by comparing a Hamming distance of the signal received from the transmitter with a locally-generated reference copy of the predetermined test signal; re-forming the predetermined test signal from the received parts, comparing the reformed predetermined test signal with the reference copy of the predetermined test signal; and generating therefrom a measure of signal degradation caused by the communications channel.