THE MAIN OBJECTIVE OF THE TESTS WAS A DETERMINATION OF CERTAIN ASPECTS OF DIGITAL DATA PROPAGATION IN THE FM MOBILE RADIO ENVIRONMENT. THESE TESTS WERE CONDUCTED IN ALLEGHENY COUNTY, PENNSYLVANIA, DURING THE PERIOD NOVEMBER 1973 AND JANUARY 1974. MODULATION TECHNIQUE SPEED OF VEHICLE, DISTANCE OF POLICE VEHICLE FROM BASE STATION, AND TIME OF DAY, WERE AMONG PARAMETERS THAT WERE VARIED DURING THE TESTS. THE AMPLITUDE AND ENVELOPE DELAY VS. AUDIO FREQUENCY RESPONSES OF THE TWO RADIO SYSTEMS USED IN THE TESTS WERE ALSO MEASURED. A GENERAL DESCRIPTION OF THE TESTS IS INCLUDED ALONG WITH A DISCUSSION OF THE LOCATION OF THE TRANSMITTING SITES AND THE ROUTES USED DURING THE TESTS. THE SECTION ON TEST RESULTS INCLUDES A COMPARISON OF THE VARIOUS DATA AND A DISCUSSION OF THE EFFECTS OF IMPULSE NOISE FADING, THE SPEED OF THE TEST VEHICLE, AND CARRIER FREQUENCIES WITH RESPECT TO ERRORS IN THE DATA. THE ACTUAL TEST RESULTS ARE REPORTED IN THE APPENDICES IN GRAPH AND TABLE FORM. (AUTHOR ABSTRACT)....KAP