In article 49eb5ac5.4793609@chupacabra,
Bob Dobbs wrote:

dave wrote:
Telamon wrote:


Well, how about analog? I have some hiss in there all the time and often
times warbling rumble kind of noise. It's very annoying and I wish they
would turn that HD crap off.


The IBOC signal is either side of the AM carrier. Each IBOC sideband is
identical but out-of-phase with the other. The theory is the IBOC
sidebands cancel each other out in your receiver. But if one sideband
propagates better than the other (which is always the case once you get
a few miles from the transmitter) the cancellation is not complete.
This is when you hear the digital hash and the wubba-wubba sound.

For those of us using a radio with selectable sideband synchronous
detection, but unable to choose USB and LSB at the same time (like my
Drake SW2) we are forced to listen in plain AM.

Sometime ago when KOGO 600 first went to band hog mode (IBOC-HD)
I tuned in to see just how bad it was and noticed that rumbling you
mentioned with the whip collapsed on the E1 for weak signal simulation,
but the DSB synch would remedy it, same with KNX.


I just tried KOGO 600, KFI 640, KNX 1070 and turning on the sync
detector didn't do anything to improve the audio. AM sounded the best.

Turning on side band selectable sync causes horrendous low frequency
noise.

By the way Australia is currently good on 17,795 as is NZ on 15,720.

--
Telamon
Ventura, California