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With what seems to be growing appearances of the Wobbler, I thought what I have found while listening for it might be of some use to others. It is on 930 here at my location in South Florida, almost all the time, day or night. I've heard it on 820 and 870 on occasion. It has also been on 910, but not lately. Most recently it was heard up and down the east coast on 1100. It has been heard in SC, GA, NM, IL, TN, PA, NY, and ON.
Should you actually want to hear the Wobbler, rather than just having it intrude on what you really are listening to, there are some ways to enhance the audio.
If your receiver has CW mode, switching to it will change the low, zero to several hundred Hertz audio signal to a higher range and make it easier to hear, especially when the Wobbler is less vigorous. The same is true for other modes like RTTY and FAX, though both, and especially RTTY may be pretty screeching.
SSB works the best I think. Other modes produce a much louder heterodyne against any other signal carrier. SSB gives an easy to hear signal that's easier on your ears. You need to de-tune to produce the pitch you like. For USB I de-tune down by 700 Hz, and for LSB, up by the same. The side band to choose is whichever one produces the best results under the circumstances. This is especially true if there is adjacent channel splatter on the Wobbler frequency.
Setting a narrower band width will help reduce other signals when using any of these methods. I use a 1.0 KHz filter setting. If your receiver has a passband control, this can also help remove the normal signal while not affecting reception of the Wobbler, or it can be used to reduce adjacent channel splatter.
All of these techniques introduce a heterodyne against any other signal, like the station you were trying to hear. This is more or less annoying based on the strength of that signal, and as a result, the volume of the resulting whistle. Using an audio filter or DSP can do wonders in removing this extraneous whine, making the Wobbler much more apparent. DSP is very good because at a high setting, it will remove the heterodyne and most of any other signal, but because of the nature of the Wobbler signal, it will cut through largely unimpeded.
One way to think of the Wobbler when tuning to hear it is that it acts like a frequency modulation of the same carrier as the dominant station you're listening to. Tuning accordingly produces the best results.
This may also be a clue as to just what the Wobbler is. Now if I only understood the clue.
W. Curt Deegan
Boca Raton, (South East) Florida
[JRC NRD-535D, LF Engineering H-800 & M-601,
Quantum Phaser, ANC-4 noise canceler, GAP DSP]
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