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CapeTalk 567 Keeps It Real With XPN-AM
Radio World Buyer’s Guide articles are testimonials intended to help readers understand why their colleagues chose products to solve various technical situations. This month’s focus is on-air audio processing.
The author is a transmission specialist for Primedia Broadcasting. He is responsible for the transmission operations of 947/702 in Johannesburg and KFM/CapeTalk 567 in Cape Town, South Africa.
The word emoji owes its humble origins to the combination of two Japanese words for “picture” and “letter,” adding dimension to what otherwise would have been a “flat” or unemotive text message.
Primedia Broadcasting kicked off the year with a fun and modern out-of-home billboard campaign for CapeTalk 567, featuring today’s lingo.
While CapeTalk 567 prides itself on keeping things “real” with listeners through its programming content, there are technical systems that must work together to get the audio to its listeners as accurately and efficiently as possible.
CapeTalk 567 has been on the air for 28 years, primarily through its medium-wave footprint, serviced by a 25 kW transmitter on the outskirts of Cape Town operated by signal distribution service provider Sentech. It also streams its audio via the Primedia Plus app and as well as the DSTV Audio Bouquet (Channel 885).
For every commercial station on the radio “dial” (be they AM, FM or digital OTT platforms), there’s an ongoing conversation about how audio can be suitably “enhanced.” This is part of creating the sonic signature that adds to the listener’s experience when tuning into a particular station.
Broadcast audio processing over the years has remained a contentious topic for radio’s creative and engineering teams. Suffice it to say, the audio processor brings together the efforts of two diverse endeavours.
From an engineering perspective, the processor takes the lead in ensuring the transmission parameters (i.e. peak modulation) are always fully respected.
The “artistic” component considers how the audio is to be manipulated to create a particular sonic signature, through increasing perceived loudness along with achieving overall consistency of the program material.
There have been changes over the last 20 years or so that have affected audio quality on traditional transmission platforms.
In the world of medium-wave AM, it is both important and appropriate to maximize the density of the received audio, to ensure the audio remains intelligible.
External noise from devices such as LED lighting, laptops, computer power supplies and electric fences may impinge on a listener’s receiver, causing degradation in overall intelligibility. Studies have shown that this increase of external noise has been as much as 20 dB.
The only mitigation would be to increase audio density.
Years ago CapeTalk 567 had elected, via service provider Sentech, to use an Orban 9200 Optimod AM, which was installed at the transmitter site. This was at the time a departure from the traditional “analog” style of processing, as it made use of digital signal processing techniques.
Through investigation and listening tests, we found that the internal processing architecture of the 9200 presented some limitations for allowing a significant increase in audio density without degrading overall audio intelligibility.
It was clear that enhancing the audio quality of CapeTalk 567 now would require replacing the processor. I considered the options and elected Orban’s XPN-AM, purchased through Orban’s SA representative Prosound. They have been responsible for Orban’s South African sales and support since 1980.
The XPN-AM would be installed at Primedia’s Greenpoint studio facility. The 9200 would be retained as a backup at the transmitter site.
Having two independent audio processing paths within the XPN — one feeding the present AM signal and the other feeding both audio stream/DSTV platforms — provided us the maximum benefit for our signals, and the added benefit of being able to adjust the unit remotely rather than while standing in front of it.
The XPN’s processing enhancements have benefited CapeTalk 567’s on-air signals. Station Manager Tessa van Staden and Technical Operations Coordinator Brett Kannemeyer both have noted improvements in audio intelligibility, clarity and consistency across its broadcast platforms.
A further significant benefit is in the processor’s application to AM systems that permit the use of Modulation-Dependent Carrier Level technology, the dynamic reduction in carrier levels with the change in modulation levels.
MDCL can produce significant savings in transmitter energy consumption, an important consideration for AM radio stations. MDCL implementation is a priority for the Sentech-owned Nautel NX25 transmitter later this year.
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