Despite the advent of the Internet and digital broadcasting standards, FM remains the world’s most popular transmission format and a central technology in radio broadcasters’ efforts to maximize their reach and audience. As a result, new technologies have had to be created to enable an FM-centric workflow to also work for Internet delivery.
The initial version of APTmpX, launched in October 2020, offered FM broadcasters access to high quality signal compression for the resulting centralized FM MPX/Composite transmission, solving the difficulty of maintaining both a high quality and a cost-effective transmission.
This provided a game-changing solution in the <900kbps region. However, the latest release of APTmpX takes this even further. Following optimization by Worldcast engineers, three new versions are available that offer new levels of compression at 600, 400 or 300kbps network bandwidth. This dramatically widens the potential impact of the technology on the industry and means that the composite signal can now directly be transported with non-destructive compression from 600kbps down to 300kbps, all at the highest sound quality.
The use of APTmpX confers several advantages. Since the majority of composite equipment at transmitter sites is eliminated with a centrally generated MPX (stereo multiplexed signal)/composite signal, besides the obvious network savings, several broadcasters have already managed to save hardware costs with APTmpX. Furthermore, APTmpX combines signal fidelity with the best latency performance and makes it easier than ever to guarantee a consistent sonic signature across the transmitter network.
APTmpX offers excellent resilience to packet loss and is highly flexible, being able to interface to analog or digital MPX sources and receivers; an APTmpX transmission link can be a combination of both. For FM-SFN (single frequency networks) applications, APTmpX is also the best choice as it keeps the highest signal transparency across multiple transmitter sites while it is fully compatible with SynchroStream, the company's highest signal synchronicity technology.
“Thanks to its low complexity and easy integration, APTmpX has already proven itself as the ultimate solution to enable a 100% digital transmission chain, bridging the transition from digital studios to digital transmitters,” comments Gregory Mercier, Director of Product Marketing, WorldCast Systems. “With these new versions, we bring its power to a whole new section of the market, allowing broadcasters in areas of poor bandwidth penetration to deliver stunning audio quality to their audiences no matter what they are listening on.”
The origins of the technology originate from the original Audio Processing Technology (APT), a company founded to bring to market the original audio compression algorithm developed in the 1980s by Dr. Stephen Smyth as part of his Ph.D. research at Queen's University Belfast School of Electronics, Electrical Engineering and Computer Science - and based on time domain ADPCM principles without psychoacoustic auditory masking techniques. APT had early success in broadcast applications, until audio compression became an important key technology for digital audio in production and consumer applications, and the company was acquired by Solid State Logic in 1988, which in turn became part of Carlton Communications in 1989. Noel McKenna and Jon McClintock led a management buyout from Solid State Logic and incorporated the business in Ireland in 2005. In 2009, APT split its business operations selling its broadcast hardware line to French broadcast manufacturer Audemat, which would later be merged into WorldCast Systems. The parent holding company and licensing division APT Licensing, responsible for licensing the proprietary APT algorithm technology (apt-X) was acquired by semiconductor company CSR (Cambridge Silicon Radio), headquartered in Cambridge, United Kingdom, and later acquired by Qualcomm in 2015.
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