Technical Reports

PTC 220 MHz Radio: SD-70M Locomotive EMI Intermodulation Testing Final Report

  • 24
  • Aug
  • 2012
AUTHOR: Meteorcomm LLC
SUBJECT: Positive Train Control, Signal and Train Control, Grants & Financial Assistance
KEYWORDS: Railroad Safety Technology Grant
ABSTRACT: This approach is deploying multiple antennas was developed by UP, consisting of two roof top boxes instead of the conventional antenna systems used by most other railroads. One of these antenna box systems has been installed on UP 4620, an SD-70M locomotive with DC traction motors. The antenna box approach permits the deployment of multiple antennas with additional spacing between them, resulting in increased FR isolation. The antenna boxes are deployed along with a complete set of new coaxial antenna cables and several band pass filters, which also contribute to improve the performance of all on-board RF equipment. The mechanical design of the roof top boxes facilitates access, maintenance and addition of more antennas, if required. The purpose of testing UP 4620 was to gather data on RF parameters including intermodulation, antenna isolation, VSWR and EMI noise. The UP 4620 has not yet been equipped to operate with PTC or distributed power radios, but the antenna boxes are outfitted with PTC A, PTC B, DP A and DP B antennas, coax cables and filters. For the testing, Meteorcomm provided and operated a Meteorcomm PTC radio, and STI-CO provided and operated four radios in the 450 and 900 MHz bands to be used in lieu of onboard radios not yet installed or not possible to operate manually for testing, such as the HOT radio. Intermodulation testing did not provide significant evidence of intermodulation products in the 220 MHz PTC band while transmitting simultaneously with several radios in different combinations. For EMI testing the locomotive was configured for a fully loaded test, sending all electrical power generated to the dynamic brake resistors. During testing the engine was stepped from notch 1 to notch 8, staying on each notch for a least a minute as readings were taken using two instruments. No significant evidence of EMI interference was found in the 216 to 226 MHz PTC band.