On Monday 09 February 2009 19:23, Brandon Jordan wrote: > I know there are some real IBOC experts on the lists and have a > question. Are most, if not all, IBOC stations precisely > on-frequency? I believe I read that IBOC required extreme frequency > precision of the carrier frequency? I am looking for MW stations to > help in accurate calibration of SDR receivers in order to measure > frequency offsets, and am hoping my memory regarding this is > accurate. > > On a positive note, I calibrated the G313e to IBOC WLAC 1510 kHz, > and was then pleased to note that IBOC KMOX's carrier measured > exactly 1210.0000 khz.
There are actually two levels of precision specified in the AM IBOC standard. Level I ("network synchronized") assumes the use of GPS synchronization, and specifies that the carrier frequency be accurate to within +/- 0.02 Hz. Level II ("non-network synchronized"), on the other hand, requires only +/- 2.0 Hz accuracy. The standard recommends that Level I precision be used "to support numerous advanced system features", but it is not a requirement. The majority of AM IBOC stations appear to meet the Level I spec and are therefore good frequency references, but there are exceptions. One notable exception is WQEW-1560, which is on 1559.9983 or thereabouts. Barry -- Barry McLarnon VE3JF Ottawa, ON _______________________________________________ IRCA mailing list IRCA@hard-core-dx.com http://montreal.kotalampi.com/mailman/listinfo/irca Opinions expressed in messages on this mailing list are those of the original contributors and do not necessarily reflect the opinion of the IRCA, its editors, publishing staff, or officers For more information: http://www.ircaonline.org To Post a message: irca@hard-core-dx.com