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....@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 <btipp...@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 > > _________________ > Topband Reflector Archives - http://www.contesting.com/_topband _________________ Topband Reflector Archives - http://www.contesting.com/_topband