Digital data transmission tests over voice channels

In order to better understand the ramifications of transmitting and receiving digital data over typical voice channels, a series of tests were performed in Allegheny County, Pennsylvania, using existing local government transmitting sites and a specially equipped mobile unit. Carrier frequency, digital data transmission rate, modulation technique, range of transmis sion, speed of the mobile unit and the time of day were varied for test purposes. Tests were conducted in both urban and suburban environments. This paper discusses test procedures, sites, routes, test equipment and the results obtained.