800 MHz Communication Survey of the Los Angeles Area

Volpe National Transportation Systems Center, Technical Reference Centerhttps://doi.org/10.21949/15272241979PDFTech ReportBalaram, A.Hajovsky, R.Heathcock, F.John A. Volpe National Transportation Systems Center (U.S.)United States. Urban Mass Transportation AdministrationUnited States. Urban Mass Transportation AdministrationLos Angeles (California)AntennasTelecommunicationsData communicationsFeasibility analysisSignal to noise ratioDigital computersAutomated vehicle monitoringDOT-TSC-UMTA-79-11;UMTA-MA-06-0041-79-5;PB-295 043DOT-TSC-1237During the first half of 1978, as part of the Multi-User Automatic Vehicle Monitoring (AVM) Program, a survey was conducted to determine the suitability of utilizing the 800-900 MHz band as the primary carrier of digital communication data pertaining to the Multi-User AVM Program. Testing was conducted on the six selected routes of the Southern California Rapid Transit District (SRTD) and specified wide area segments in the city of Los Angeles. The field testing involved usage of a test vehicle, communication equipment, both on the vehicle and at the base station, and data acquisition equipment. Results on the area coverage, large and small scale signal variations, message error mechanisms, antenna polarizations, usage of different base station sites, usage of different baud rates, and comparison with model prediction were obtained. The study also involved taking field measurements of such parameters as the noise level, the signal level, signal/noise ratio, throughput, and message errors. The results of the 800 MHz Survey indicate that: 1) Multiple base stations will be required to provide the specified coverage of the six selected SCRTD bus routes; 2) the results indicate that the use of a circularly polarized antenna system does not reduce the effects of fast fades compared to a vertically polarized antenna system; and 3) Baud rates between 1000 and 1800 BPS can be used effectively for the transmission of digital data using commercial 800 MHz mobile radios presently on the market.138