Harris Broadcast Communications engineers worked with Tom Ray, corporate DOE at Buckley Broadcasting/WOR(AM) in New York, to test the compatibility of several MDCL algorithms with AM HD Radio and Arbitron Portable People Meter data encoding/decoding.
Overall the tests were successful, the participants said. Ray stated “Buckley/WOR looks forward to saving over $3,000 per month on our transmitter site power bill” using the MDCL power reduction technology.
MDCL stands for Modulation-Dependent Carrier Level. It’s a power reduction algorithm technology that Harris says can provide a significant reduction in transmitter power consumption without impacting audio quality, signal coverage, HD Radio operation or Arbitron audience rating data.
WOR received an FCC waiver permitting “on air” MDCL tests that were conducted on a 50,000 Watt, Harris 3DX-50 transmitter feeding a three-tower directional antenna array. WOR’s programming format is mostly talk radio with moderately heavily processed audio.
The algorithms tested were Amplitude Modulation Companding (AMC) with a carrier reduction level of 3 dB at peak modulation, and Adaptive Carrier Control (ACC) at carrier reductions of 2dB, 3dB and 6dB at minimum modulation.
The initial tests found that AMC was the most compatible with simultaneous HD Radio operation, causing no noticeable change in HD Radio coverage, according to Harris and WOR. AMC also provided the largest reduction in transmitter power consumption, by saving 37% in average AC power input to the transmitter.
The AMC and ACC modes tested were compatible with Arbitron PPM data collection, according to participants, who added that measurements made by Arbitron in New York showed no PPM data errors during the “on air” tests of any MDCL operating mode.
Listening tests at weak signal areas on several different types of receivers with digital, analog and synchronous AM detectors showed no noticeable loss of audio quality.
“It was surprising that there was no impact on our coverage or audio quality. That’s a lie — we were actually louder in weak signal areas. And I was floored by the 37% reduction in AC power consumption,” stated Ray.
Stations Begin Exploring Power-Saving MDCL (Oct. 2011)