Here is a recording (made on 80M a few years ago but sounds substantially
the same on 160M) of what I'm told is the Wallops Island Ionosonde:
http://n3qe.org/wumwum_80M.wav
Here is the waveform showing 4 louder cycles followed by three softer
cycles:
http://n3qe.org/wumwum.png
If you look at the second panel of the waveform, you see a 20Hz
substructure in the pulses.
Even though I'm sitting in once place with a 2.4kHz filter making this
recording, I understand that the actual spectrum occupied is wider and it
cycles through the bands repeating on a several minute cycle.
Tim N3QE
On Thu, Feb 22, 2018 at 12:56 PM, Jim - WS6X <ws6x.ars@gmail.com> wrote:
> I too, am curious as to the source. I heard it for many years in Central
> California; hear it at my current QTH in Central Shenandoah Valley; and
> heard it last weekend at NR4M.
> I describe it as a scratchy sound, sometimes with a bit of tonality.
> Always 4 pulses (although I don't think I've ever heard the 4 followed by 3
> as Bill describes.). I've never timed the interval between the groups of 4,
> but it is fairly infrequent. I'll hear it throughout the evening when I'm
> at the radio for long periods. It is loud enough on 160 here in VA that it
> will wipe out all but the strongest signals. I will have to pay more
> attention to details and record when I hear it.
> I wish I was better at phonics, but what I hear has distinct articulation:
> "Gugghk gugghk gugghk gugghk". 😊
> Jim, WS6X
>
> 1. Speaking of noises... (Bill Tippett)
> Message: 1
> Date: Wed, 21 Feb 2018 12:48:20 -0500
> From: Bill Tippett <btippett@alum.mit.edu>
> To: topband <topband@contesting.com>
> Subject: Topband: Speaking of noises...
>
> Does anyone know the source of periodic wideband buzzes that sound like
> this:
>
> buzzz..buzzz..buzzz..buzzz (i.e. 4X then pause) buz..buz..buz (3X ~10 dB
> down).
>
> I believe this may be some sort of ionospheric sounder but I've heard this
> for decades, including when I was in Colorado. Hopefully someone knows
> what's generating this.
>
> 73, Bill W4ZV
>
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