Radio Road Which tuner to get and getting the most from it. Thank God, for the radio!

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Noise, even on a strong station: Update

Posted by FidPup (A) on June 13, 2012 at 09:59:53

I think I have figured out what is causing the noise I am hearing when listening to two strong local stations on my Etude tuner, as referenced in my thread below:

http://www.audioasylum.com/forums/tuner/messages/1/13436.html

(openmind had hit the nail on the head in the original thread...)

As I stated previously, my two favorite Dayton, Ohio area stations are WYSO (50,000 watts, 4 miles SSE) and WDPR (600 watt classical, 22 miles ESE).

Even when either station is perfectly tuned I hear constant low-level noise superimposed on the audio that is similar to the "white" noise heard with a weak station, but a bit more harsh and "swishy".

The tuner is connected to a six-element yagi antenna on a rotator in my attic. Both stations show full strength on the tuner's signal strength meter, and multipath shows zero.

The noise increases symmetrically as either station is de-tuned off center, but it cannot be eliminated, no matter how carefully tuned.

I can markedly decrease (but not quite eliminate) the noise by switching the tuner to its narrow bandwidth.

I have finally been able to experiment with re-orienting my antenna...

There is no change in quality or level of the noise when the antenna is pointed directly at either station, and the noise does not increase at all until the antenna is moved to roughly 70 degrees to either side of centered. In other words, even on the weaker of the two stations I can sweep the antenna through an arc of about 140 degrees without the noise increasing or decreasing.

After additional research I have come to a conclusion...

Both of the stations in question are Public Radio stations, and both broadcast a HD radio signal.

I am pretty sure what I am hearing is "HD radio self-noise". See the excellent outline here:

http://www.ham-radio.com/k6sti/hdrsn.htm

Now I guess I need to see if there is any way I can hear the otherwise excellent, unprocessed and uncompressed audio from these stations (the classical station actually uses tube gear in their broadcast chain!) without the noise intruding.

Temporarily I can tolerate the noise if I listen to the tuner in narrow IF bandwidth.

It sounds like the "real" fix is to use a tuner that includes a "post-detection filter" or equivalent design, but I wonder if the newer, more selective Magnum Dynalab tuners (MD-100 or higher) would be more able to reject the HD radio self-noise? I really love the sound I get with my Etude!

Maybe the Magnum Dynalab MD-205 Signal Sleuth might help?

I can find no information anywhere specifically about the ability of the newer tuners or the Signal Sleuth to reject HD radio self-noise.

Any comments or advice will be welcomed!

Ken

Edits: 06/14/12

This post is made possible by the generous support of people like you and our sponsors:

Kimber Kable

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