Monday, February 11, 2008

IBOC Rules The Waves - Or Waives The Rules?

"Impressive" bandwidth KSL has here. 30 kHz just to make so-called High Definition AM? Did FCC approve this? One can become a DRM-fan for less. Wait! No. One can't. Ever.


Gert Nilsson said...

No carriers from the Europeans! What a difference! No wonder your nice DX-catches!

carmen said...

indeed a sad waste of spectrum. the FCC of course favors the highest bidder these days. so i guess we can expect about 3 stations taking up the entire band wtih 200kHz0-wide ultra-HD offerings soon

JLS said...

Regarding .1
...not to mention the noisefloor!

Bjarne Mjelde said...

JLS, when playing back an SDR-IQ file the signal level appears to be 20-30dB or more higher than during ordinary decoding (I haven't measured the difference yet; I will). So KSL did not have a -35dBm signal level, still it was very strong. The difference in signal level must be a bug in Spectravue.

Gert Nilsson said...

I agree about the Spektravue bug.

Anonymous said...

I am not aware of IBOC; Does this mean that IBOC has digital stuff on both sides of the AM carrier and simulcasting the AM on nominal? DRM usually has the digital signal about 10-20 kHz wide and sometimes simulcast AM on upper or lower side (like 693).
Do we have the list of all IBOCs somewhere - when visiting Lapland in December quite a few channels seemingly had digital on.
73 Tarmo

Bjarne Mjelde said...

Tarmo: Basically yes. IBOC wanted the signal to be audible on analogue radios as well as on HD radios.Since you can't put a digital and an analogue signal on the same bandwidth without them interfering each other, they had to put the digital signal outside of the analogue passband. Commercially (for Ibiquity) it is probably a much better solution than DRM which means you have to replace analogue receivers with HD receivers. Commercial broadcasters would probably not survive the transition period. According to Ibiquity there are 259 AM stations (out of 1618 total) currently using IBOC, but many are not on at night (and reports say some have quit for various reasons).

PocketRadio said...

HD/IBOC jams on both AM/FM - it is a scam by the larger broadcasters to jam the smaller one off the dial:

"What Are We Doing to Ourselves, Exactly?"

"IBOC FM Interference Has Been Reported in Several Cases Where FCC Contours Provide Inadequate Protection."

"HD Interference: Not Just For AM Anymore"

"Radio World Engineering Extra dropped a bomb this month with a very provocative cover story: 'What Are We Doing to Ourselves, Exactly?' Written by Doug Vernier, the man who authored the technical specifications for an ongoing Corporation for Public Broadcasting-sponsored HD Radio interference analysis, the report is the first of its kind to document interference between FM-HD stations around the country. Using anecdotal reportage, some sophisticated contour-mapping, and presumably 'early data' from the CPB study, Vernier's article conclusively proves how stations running in hybrid HD/analog mode can (and do) interfere somewhat significantly with not only themselves, but their neighbors on the FM dial."

"Editorial: AM IBOC in Distress?"

"Citadel Director of Corporate Engineering Martin Stabbert embodied questions about the efficacy of full-time AM HD when he ordered all his AMs that had already converted to cease transmitting HD at night, using language that must have given Ibiquity officials heartburn. Separately and for different immediate reasons, Cox, in a “let’s wait and see” move, has tried HD on most of its AM stations but is taking it off the air day and night, once tested at each facility."

"AM Broadcasters Back Away from HD Deployment"

"This is a major setback for the adoption of HD Radio, especially on the AM dial, and Citadel is the first large broadcast conglomerate to back away from full deployment of the HD broadcast technology. Although the company's gone out of its way not to characterize its move an indictment of iBiquity's proprietary digital broadcast standard, the problems with AM HD broadcast interference are well-known and -documented."

PocketRadio said...

Everything about the HD Radio scam is here: