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IBOC / HD Radio TM : Engineering Concerns Aaron Read (G.M. : Public Radio for the Finger Lakes)

IBOC / HD Radio TM : Engineering Concerns Aaron Read (G.M. : Public Radio for the Finger Lakes). Already decided HD Radio TM is right for you? Here’s a look at what you’ll need to do. Essential Questions.

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IBOC / HD Radio TM : Engineering Concerns Aaron Read (G.M. : Public Radio for the Finger Lakes)

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  1. IBOC / HD RadioTM : Engineering ConcernsAaron Read(G.M. : Public Radio for the Finger Lakes) Already decided HD RadioTM is right for you? Here’s a look at what you’ll need to do. No, your presenter is not “drinking the iBiquity Kool-Aid”

  2. Essential Questions • This session is not about whether or not your operation can deal with the various issues involved with HD Radio. • We’re here to look at what’s involved with the engineering behind installing HD Radio at your facility or facilities. See also : http://www.hdradio.com and http://www.dreinc.com

  3. Are you an AM station? • If you don’t have an FM station, be advised: we’re not going to talk much about AM IBOC. • It has a lot of problems and the entire future of AM IBOC is arguably still in question. • Digital sidebands cause significant 1st adjacent interference – nighttime skywave means that interference goes 1000’s of miles. • Audio quality improvements are impressive for music but sounds pretty “crunchy” for news/talk. See also : http://www.hdradio.com and http://www.dreinc.com

  4. What is HD Radio?Hint: the “HD” doesn’t stand for anything! • HD Radio is a brand name by the creator: iBiquity • Technical term is IBOC : In-Band/On-Channel. • Uses digital sidebands on your existing analog signal. • These sidebands do put some more RF energy on the adjacent channels, so IBOC can cause 1st-adjacent interference issues. • Backwards-compatible, existing analog radios ignore the digital (sounds like “white noise”) See also : http://www.hdradio.com and http://www.dreinc.com

  5. Is HD Radio required? • No – it is currently a hybrid system: both analog and digital. Fully backwards-compatible, and (by FCC R&O) optional for stations to migrate. • All-digital system is possible, but FCC not allowing it. • All-digital does hold promise for more data b/w and less interference issues. • Note that eventually it’s likely the marketplace / listeners will demand you migrate to HD. See also : http://www.hdradio.com and http://www.dreinc.com

  6. What is HD Radio?Also known as “IBOC” • IBOC-equipped radio will first play the analog audio feed immediately, then begin buffering the audio data. • This results in approx. 7 second delay of program audio. • After a few seconds, the radio will “blend” to the digital audio feed. • Make sure your analog & digital audio feeds are time-synched! • Digital audio uses the HDC codec. Details are proprietary, but rumored to be a variant of the impressive AAC codec. • If the HD signal is lost, the radio blends back to analog. See also : http://www.hdradio.com and http://www.dreinc.com

  7. Simple FM IBOC Transmission Topology – All IBOC Gear at Transmitter Sitediagram courtesy of The IBOC Handbook, page 401 See also : http://www.hdradio.com and http://www.dreinc.com

  8. FM IBOC Transmission Topology – with Exporter and Exgine Modulesdiagram courtesy of The IBOC Handbook, page 405 See also : http://www.hdradio.com and http://www.dreinc.com

  9. FM IBOC Transmission Topology – with Exporter & Exgine Modules, plus Importerdiagram courtesy of The IBOC Handbook, page 413 See also : http://www.hdradio.com and http://www.dreinc.com

  10. What is HD Radio? (FM)Also known as “IBOC” • The digital carriers merely transmit data: ones and zeros. • 96kbps in standard mode • 96kbps + 12 or 24kbps in extended hybrid modes • Ext.Hybrid puts more digital carriers closer to the analog signal – more risk for self-interference. • That digital payload can be divided in many ways, and not just for audio. See also : http://www.hdradio.com and http://www.dreinc.com

  11. What is HD Radio? (AM)Also known as “IBOC” • Also just transmits bits, but less bandwidth – about 32kbps total. • Multicasting is not available yet. • Does have enough data (barely) for PAD. • Chief advantage is in improved audio quality. • Is authorized for operation at night and on directional arrays. See also : http://www.hdradio.com and http://www.dreinc.com

  12. What benefits does IBOC have? • Robustness = no static, no fades, no multipath • Quality = increases audio b/w from 15 to 20kHz (i.e. more high end) for FM. • Note, “quality” does not mean “fidelity” – it’s still a lossy codec…but on FM it’s impressive. • On AM, it’s more complicated, but generally better. • Flexibility = transmits DATA not AUDIO. You can, in theory, use those bits for lots of things. • PAD, iTunes tagging, MP3 downloads, on-demand text/audio/video. See also : http://www.hdradio.com and http://www.dreinc.com

  13. FM IBOC’s Killer AppMulticasting = Extra Radio Stations on 1 Signal • HD1 must always be a simulcast of your analog signal. • Multicasting changes 96kbps for HD signal into subdivisions: • 48kbps each : HD1 & HD2 • 32kbps each : HD1 & HD2 & HD3 • 48kbps : HD1 + 24kbps each : HD2 & HD3 • Extended hybrid’s bits cannot be added to the 96kbps, but can be used alone for a single multicast channel. • 48kbps each : HD1 & HD2 + 24kbps : HD3 • Theoretical max up to HD7, practical limit is HD3 • Less kbps = less audio quality • HD4 is possible but problematic in many ways. See also : http://www.hdradio.com and http://www.dreinc.com

  14. FM IBOC’s Killer App???iTunes Tagging • www.hdradio.com/iTunes_Tagging • Equipped radios have a “tag” button. • Press when you hear a song you like. • Radio saves tag info to your iPod. • When iPod is connected to iTunes, it goes to iTunes music store and buys the song for you. • Very cool – but limited receivers, limited number of stations doing it. Requires massive investment in audio content mgmt & promotions. See also : http://www.hdradio.com and http://www.dreinc.com

  15. FM IBOC LimitationsThe -10 vs -20dB Debate : NPR Labs Study • IBOC injection is -20dB or 1/100th of analog ERP (1000w analog = 10w digital) • Coverage is considered inferior to analog • Proposals to increase IBOC inj. to -10dB of 1/10th of analog ERP. • Risk of severe adjacent channel interference. • Avg. 26% loss of analog coverage / 41% of stations receive interference to one-third of service population. • …but portable HD may not work without it. See also : http://www.hdradio.com and http://www.dreinc.com

  16. FM IBOC LimitationsThe -10 vs -20dB Debate : NPR Labs Study • Summer 2008 – NPR Labs released first comprehensive, accurate IBOC coverage prediction model. • At current -20dB IBOC ERP levels… • Mobile coverage = equivalent of analog • Indoor coverage = 50% of analog • At -10dB IBOC ERP levels… • Mobile coverage = +18% over analog • Indoor coverage = 88% of analog See also : http://www.hdradio.com and http://www.dreinc.com

  17. FM IBOC LimitationsThe -10 vs -20dB Debate : NPR Labs Study • Hi-Level Combined Xmitter Systems will require SIGNIFICANT extra capacity. • Current HD xmitters de-rated by up to 50% • Take a 20kW analog ERP station… • @ -20dB : ~23kW analog + ~2kW digital • @ -10dB : ~23kW analog + ~21kW digital • …and ~21kW going into the reject load!!! • Different for split-level combined, combined, or separate systems – but you get the idea: it’s not just a case of adding more watts. See also : http://www.hdradio.com and http://www.dreinc.com

  18. FM IBOC Challenges • IBOC requires time-delay of analog to match the digital – this can complicate your off-air monitoring scheme. • Normal silence sensors may not work effectively. • Adding HD2 and HD3 is essentially like buying two new stations. It introduces significant challenges in programming, operations control, monitoring, etc. • Do you have trouble filling ONE station with programming 24/7? Imagine adding two more! Or two more studios! • Managing listener expectations – when the HD signal is lost, it just disappears immediately. That means HDn channels just mute (instead of fading out to static). See also : http://www.hdradio.com and http://www.dreinc.com

  19. FM Translators and Boosters • Boosters (Single Freq. Network) • NRSC-5 specs carrier synch, but no radios support it yet. Right now it’s only in prelim testing. • Relates to the -20 vs -10dB IBOC injection debate. • Translators require* a separate exporter license from iBiquity = big bucks for a small signal. • * unless you get a heterodyning xlator, which are still vaporware and are pricey ($10-$20k) See also : http://www.hdradio.com and http://www.dreinc.com

  20. FMeXtra? • Digital SCA (Subcarrier) service • Compatible with hybrid IBOC, but not all-digital IBOC. • Transmits 64 – 156kbps • Stereo, RDS, analog SCA = less kbps avail. • Transmits DATA, but architecture only supports audio via AAC at the moment. See also : http://www.hdradio.com and http://www.dreinc.com

  21. FMeXtra • Not meant as a multicast service, but can be used that way. • Really meant to supplant existing analog SCA • Only one model of radio currently available: tabletop “Aruba”. FM only. • Can function as a handy backup STL / TSL system (yourself or rent to others) • AAC codec = quality audio @ low kbps See also : http://www.hdradio.com and http://www.dreinc.com

  22. Shameless Self-PromotionThe IBOC Handbook : Understanding HD RadioTM Technology • Looking to really learn the engineering of IBOC / HD Radio? Read this book! • First & Only Overview of the Newly-Approved NRSC-5 (IBOC) Standard. • Authored by David Maxson • Illustrated by Aaron Read • Available on Amazon.com See also : http://www.hdradio.com and http://www.dreinc.com

  23. Final Thoughts • Questions – and please no: • Rants, Screeds, Diatribes, Harangues, Raving, Tirades, Bullyragging, Vociferation, Bloviating, Railing, Objurgating, Badgering, Molestation, Nettling, Ruffling, Badgering, Pestering, Heckling or Persecution. • Tell us your situation, we’ll opine if HD Radio or FMeXtra is right for you! Aaron Read can be reached via www.friedbagels.com/blog Need an engineer? www.sbe.org See also : http://www.hdradio.com and http://www.dreinc.com

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