Abstract :
An improved method is presented whereby a radio repairman can test the audio performance of a phase modulated transmitter in a mobile unit at an isolated location using a minimum of time and test equipment. Testing is done with signals at normal operating levels, as well as above limiting, to obtain a more uniform adjustment of modulation in different transmitters. When this is combined with other measurements that are more familiar, the repairman can obtain an index of audio performance at the mobile unit for both transmitting and receiving conditions. A reliable index is particularly useful in connection with narrow band operation as well as in wide band systems that are large enough to include mobile relay stations or multiple repeaters. Examples are given showing that previous methods of adjusting modulation in the field are inadequate for some present applications.
