[Electronics-Talk] am/fm tuning in an hd market

[Andrews, David B (DEED)]

Steve has given you a good explanation.  It shouldn't be more difficult, but it is RF after all, and odd things can happen depending on your antenna and your location.

The other thing to remember is that the way most radios work is that they tune in the analog signal, and if an HD signal is present they change to it after about 7 seconds. This is because analog is essentially real-time, and digital must collect enough data to decode the signal -- hence the delay.  If the station is properly engineered, this blend from analog to HD should be seamless, or almost so.  If not, there will be a stutter or worse.  Also, if you have a marginal digital signal, it may blend back to analog, and can even go back and forth. Try moving your antenna, or getting a better one.

With many HD radios there are different antennas for AM and FM.

Dave



David Andrews | Chief Technology Officer
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-----Original Message-----
From: Electronics-Talk [mailto:electronics-talk-bounces at nfbnet.org] On Behalf Of Steve Jacobson via Electronics-Talk
Sent: Wednesday, May 01, 2019 9:01 AM
To: 'Discussion of accessible home electronics and appliances' <electronics-talk at nfbnet.org>
Cc: Steve Jacobson <steve.jacobson at visi.com>
Subject: Re: [Electronics-Talk] am/fm tuning in an hd market

It is possible you are having more problems because of HD signals.  If you have a radio with digital tuning, you should not experience any difficulties on FM or AM.  However, if you have an analog  radio that employs some kind of Automatic Frequency Control sometimes called AFC, it can sometimes lock on to the HD portion of the FM signal instead of the analog part.  This won't happen all of the time, because there are some other variables.  While the HD portion of an AM signal is very apparent when one tunes, I am not aware of any reason you should have more trouble getting those signals with careful tuning.  You will hear an obvious sound on either side but the actual analog signal should be as clear as ever.  This may make a strong AM signal seem narrower, though, and might cause you to miss a station while tuning.  However, a strong AM HD signal could interfere with an analog station right next to it on the dial.  This can be a problem particularly at night when more frequencies contain receivable stations, but is not usually an issue during daylight hours.

Best regards,

Steve Jacobson

-----Original Message-----
From: Electronics-Talk <electronics-talk-bounces at nfbnet.org> On Behalf Of Jude DaShiell via Electronics-Talk
Sent: Wednesday, May 1, 2019 5:38 AM
To: electronics-talk at nfbnet.org
Cc: Jude DaShiell <jdashiel at panix.com>
Subject: [Electronics-Talk] am/fm tuning in an hd market

It seems to be more difficult to tune and lock onto am and fm stations with standard radios in an hd heavy marketplace.  Is that actually the case or do I have a defective radio?