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eHam Forums => Software Defined Radio => Topic started by: AC1LC on March 19, 2023, 01:38:45 PM

Title: Strange signal running across my waterfall
Post by: AC1LC on March 19, 2023, 01:38:45 PM
I'll start out by saying that I just purchased a Yaesu FTDX-10.  This is my first radio with a waterfall screen on it, I'm coming from a Yaesu FT-450D so the display is a whole new experience for me.

I am seeing what looks to be a short signal run across the face of the screen from left to right.  I don't hear anything, only see the little visual clue.  I have no idea of what it is.  Anyone have anything similar and figured out what's doing it?  I don't live close to any airports so I don't think it's a radar sweep.  Seems to happen more on 40m than 20 or 10.

It's not causing a problem, I'm just curious as I'm trying to learn all the in and outs of this radio.  Going on day 3 now.
Title: Re: Strange signal running across my waterfall
Post by: KC6RWI on March 19, 2023, 01:49:45 PM
I don't have the answer, but I have seen that as well and maybe a upsweep sound. I've seen signals that go from side to side almost like they are digging a hole here and then over there, thats a really non technical description, but thats what I have seen on the 7300.
There is another signal I have seen, it sounds like a buzz saw and it looks like the thread of a bolt.
It would be interesting to know the source, and I would guess that the signals need not be local, they maybe coming from a distance.
Title: Re: Strange signal running across my waterfall
Post by: K6SDW on March 19, 2023, 02:49:56 PM
I too have the same wave form on my 7300, especially on 10 meters....I'm not an expert, but I would guess we're seeing RFI from grow lights and switching supplies in general...they are everywhere, and some are not well designed, but very cheap.

The ARRL website has articles on this subject.

GL/73
Title: Re: Strange signal running across my waterfall
Post by: W4NBO on March 19, 2023, 04:57:23 PM
Ionosonde?
https://www.youtube.com/watch?v=-V4HPW6QjpQ
Title: Re: Strange signal running across my waterfall
Post by: KF4HR on March 19, 2023, 06:45:39 PM
See if you can isolate the source.  Perhaps its internal (to the rig), or from an external source.  Unplug your antenna and see if the strange signal disappears.
Title: Re: Strange signal running across my waterfall
Post by: K0UA on March 19, 2023, 06:58:33 PM
Are you talking about the little ionsonde's that go zipping past at great speed and you hear a "blip" as it goes across your center frequency?
Title: Re: Strange signal running across my waterfall
Post by: K0FL on March 19, 2023, 07:50:25 PM
What you describe is most likely a power supply. And I would guess most likely your power supply. Try the radio on battery and see if it is still there

Good luck es 73
Tim
Title: Re: Strange signal running across my waterfall
Post by: K6AER on March 19, 2023, 08:00:09 PM
What you are seeing is just a ham transmitting and running the VFO up and down the band to check VSWR. I see it ll the time on HF.
Title: Re: Strange signal running across my waterfall
Post by: N2HUN on March 20, 2023, 03:47:27 AM
Sounds exactly like a ionosonde or "chirp sounder" that moves across the screen and has a "zwoop-like" sound if you are using SSB. Many more are appearing these days due to improving band conditions.

Some go up the band, others go up then reverse, very interesting to watch.

Good article to read:https://www.rtl-sdr.com/chasing-ionosondes-with-an-rtl-sdr-dongle/
Title: Re: Strange signal running across my waterfall
Post by: AC1LC on March 20, 2023, 06:07:05 AM
Ionosonde?
https://www.youtube.com/watch?v=-V4HPW6QjpQ

That looks like it.  Mine is a single signal that runs from low to high in the frequencies but other than that it is acting the same.  Never heard of Ionosondes before.  Thank you for posting this.
Title: Re: Strange signal running across my waterfall
Post by: KD2HCU on March 20, 2023, 06:08:58 AM
On my Xiegu g-90 I rarely get a wave looking thing that starts at both ends and gets higher and collide in the middle then disappears.  G-90 is also a SDR.
Title: Re: Strange signal running across my waterfall
Post by: N8NK on March 20, 2023, 07:19:07 AM
Oh man, it would be a grin if everyone is just describing 'band swoopers'! Band swoopers have existed since before radio. Radio was only invented to give band swoopers a way of swooping the ham bands. I know this to be true. Hey wait- that sounds wrong somehow...
I was thinking the other day how band swoopers here in the 'states provide a service. They give ham radio ops and showtwave listeners 'hanging out in the bands' that 'nostalgic ham radio sound' that we've known and loved forever! It's truly nostalgic, romantic, and wonderful.
Chuck, N8NK
Title: Re: Strange signal running across my waterfall
Post by: KB2WIG on March 22, 2023, 10:07:51 AM

Skip,


For you it's probably the Boston Buzzy.

KLC
Title: Re: Strange signal running across my waterfall
Post by: W9WQA on March 22, 2023, 03:13:45 PM
make your own.  probably a vna sweeping an antenna.
its fun to span around a freq. great for learning vna tricks.
great for learning vna cw/sweeping/ spanning...

tune to a freq. span a cw aruund it,  1 khz,  10 khz,  i mhz
!!

my 7300/ 705 are very entertaining...and my vna with a wire
Title: Re: Strange signal running across my waterfall
Post by: KC6RWI on March 22, 2023, 04:35:44 PM
So my vna is also a qrp transmitter? I guess there is a tiny signal that might be emitted.

there is one sound I have heard in all my days of radio, a bubble up sound, I once thought it was an indicator of good band conditions.
Title: Re: Strange signal running across my waterfall
Post by: N2HUN on March 23, 2023, 02:58:37 AM
Antenna analyzers use a small amount of power in order to determine Standing Wave Ratio so yes it's possible that your VNA is emitting a signal.
Title: Re: Strange signal running across my waterfall
Post by: W9WQA on March 23, 2023, 12:51:10 PM
or guy next door, or in next state, or country...
Title: Re: Strange signal running across my waterfall
Post by: KC6RWI on March 23, 2023, 02:20:50 PM
How can you be sure a vna sweep is correct in analyzing an antenna? The voltage and current is so low, then after the sweep your radio will  apply a much higher voltage and
100 watts or more
You know how electrons will take the path of least resistance especially at higher voltages, just fiddle with the spark plugs when the engine is running.
So can you be sure vna is really the best indicator.
Title: Re: Strange signal running across my waterfall
Post by: W9WQA on March 23, 2023, 03:05:48 PM
"So can you be sure vna is really the best indicator."

or ANY  swr readout...???