Wheatstone® baseband192 Works with BE FM EXCITER

Wheatstone® baseband192 Works with BE FM EXCITER

BE STXe60NEW BERN, NC, USA (August 7, 2013) – On the heels of last week’s breaking news announcing KTWN-FM’s initial broadcast from an all-digital air chain using Wheatstone® baseband192, Wheatstone now announces the successful connectivity of its digital “last mile” interface into Broadcast Electronics’ (BE) new STXe60 FM exciter.

Testing was completed at BE’s factory in Quincy on Friday, representing a 100% digital air chain. “We are pleased to see so much support from major manufacturers,” said Jeff Keith, Wheatstone senior product design engineer. The digital interface is available as a standard feature in Wheatstone AirAura X3, FM-531HD and VP-8IP audio processors to produce an AES-EBU output into FM exciters now equipped with a digital baseband input. Wheatstone baseband192 was initially interfaced to a transmitter for a first in broadcast history at KTWN-FM, Minneapolis, a little over a week ago.

On August 2, BE factory tested Wheatstone’s VP-8IP audio processor with baseband192 into its new STXe60 exciter; no additional processing hardware was required. Wheatstone baseband192 was built into the Wheatstone processors four years ago but had been held back until FM transmitter manufacturers could offer a digital multiplex interface to their transmitters. Following announcements at the recent NAB 2013 convention, FM exciters became available that could accept the necessary digital multiplex signal. With baseband192 directly connected into the baseband input of their FM exciters, broadcasters are able to complete the “last mile” of the 100% digital FM air chain, from the audio playout system to the transmitter’s digital FM modulator.

Previously, broadcasters had two options for interfacing the audio processing to the exciter: analog composite or digital AES/EBU (AES3). The first required D/A and A/D conversion and resulted in unpleasant audio artifacts typical of this method. The other, although digital, didn’t offer a composite interface and therefore came at a loudness penalty due to the loss of any downstream benefits generated by the FM processor’s composite clipping. Wheatstone’s new, third interface option for its audio processors doesn’t require A/D/A conversion or come with a loudness penalty. Because the baseband192 signal encompasses the entire multiplex spectrum after stereo generation, it includes any loudness increases that may have been contributed by the FM processor’s composite clipper. A single AES-EBU cable between the Wheatstone processor and the transmitter carries the baseband signal, bypassing the need for multiplexing in the exciter and eliminating the resulting signal overshoot and associated loudness tradeoff.

“Broadcasters spend a lot of time maintaining absolute purity in their audio chain and tweaking their processing. For the first time, a theoretically perfect interface exists to make sure all that hard work pays off in the form of pristine audio on the air, with no loudness compromises,” commented BE Senior Software Engineer Wes Keene. Baseband192 is a 192kHz sample rate, pure digital interface. The baseband192 signal represents the FM processor’s entire stereo multiplex spectrum – including most subcarriers. The stereo multiplex signal remains in the digital domain after stereo generation so there are no D/A conversions, no sample rate conversions, and no imperfect analog circuitry standing in the way of a perfect handoff of the stereo baseband signal to the FM exciter.

Baseband192 is being offered to broadcasters as a standard feature on new orders and as a free software download for existing AirAura X3, FM-531HD and VP-8IP audio processors. BE’s baseband capability will be available in any second generation BE STX product - including the full line of STX LP transmitters and the STXe60 and STXe500 products. BE’s STXe60, a 'Pick Hit' winner at NAB2013, is a complete re-design of the exciter portion of BE's STX product line. This design includes full digital direct-to-carrier modulation and now, with baseband192 compatibility, is able to offer a 100% digital chain. This exciter is standard on all transmitters currently shipping at BE.

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