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PolyPhaser: RF interference filters

RF interference caused by PTC radios operating at different modulations has been a problem that railroads have acknowledged and worked to overcome since the start of PTC planning and installations. For example, a 220 MHz radio located in close proximity of 160 MHz voice radios and 450MHz EOT/DPS radios causes intermodulation issues. These can be overcome with the use of filters manufactured by PolyPhaser.

However, a more complicated interference problem is presenting itself in the Northeast corridor of the U.S., where 220 MHz radios are being operated by freight railroads on the same or nearby tracks as transit trains operating their PTC (ACSES) radios at 219 MHz.

"Fixing interference problems between adjacent frequencies requires a much more sophisticated filtering solution than our standard RF filter series," said Jason Mies, Transportation Business Manager for PolyPhaser. "That's why we are working closely with the industry to develop a solution to this new problem so the operators can achieve interoperability by the impending deadline."

ARMS (Automated Railroad Maintenance Systems Inc.) is the industry distributor and integrator for Polyphaser Filters and is planning closely with the company, railroads and transit agencies to share this fix as soon as the product is available.