Addressing my complaint that my local KFI 640AM tends to be noisy on my digital radios, Gary writes:
Some of the problem might be due to KFI being an HD Radio (IBOC) station. I find their signal to be quite noisy unless it's tuned exactly. Inexpensive digital radios generally tune in rather course 1 kHz (or 10 kHz) steps, so it's often not possible to fine tune for the least noise. At my location, KFI often sounds less noisy on an analog radio that is carefully tuned than it does on a digital radio.
I don't have this problem with powerful non-IBOC stations like KRLA. I wish HD Radio on AM would go away.
The answer is yes -- HD radio causes interference, and it is noticeable for AM. This is not a subjective question, it is a simple issue of electrical engineering. The FCC, in approving HD radio, apparently felt the trade-off was worth it.
At the time HD radio was approved, I was quite skeptical of both its business case and engineering case. I am very sorry that my skepticism has proved to be well-founded. HD radio has worsened the radio experience for the average listener. HD Radio has proved such a flop that the vast majority of non-car radios offering "HD" have been withdrawn. (Because of the way HD radio works, I think it is an especially awful engineering choice for car radios, but I am not sure what the actual market impact has been.)
What a farce.
Posted by: Doug T. | May 18, 2013 at 08:32 PM
The Silicon Labs 477x Chip - A New DSP DX Champ?
http://radio-timetraveller.blogspot.in/2012/08/the-silicon-labs-477x-chip-new-dsp-dx.html
Posted by: vimal oberoi | May 21, 2013 at 11:26 PM