Received signal patterns - waterfall

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  • Updated 3 years ago
I was wondering if anyone could explain why I see these patterns on received signals.

One of my friends switched between 3 different rigs and the specific pattern persist....quite strange.






Thanks
Mario
KC8P

 
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KC8P

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Posted 3 years ago

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K0UNX

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Hmmm.  3 different rigs, but same pattern.  Antenna related?  Maybe he needs a COMMON MODE CHOKE at the ANTENNA feed point?
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Walt - KZ1F

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I don't know that this will directly answer your question but I've seen whole words spelled out in the waterfall. One would never tell that from the spectrum display but clearly in the waterfall there were words. In the top waterfall above, it does look like something of a video interference pattern.
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Danny K5CG

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Here's one I captured a couple of weeks ago.
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Peter K1PGV, Elmer

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You can transmit a pattern that causes the waterfall to show your callsign or the mode that you're using with fldigi... the mode thing can be cute if you're using an obscure mode.  I don't use it, personally, but I see how it might be useful.  I guess.

Peter
K1PGV
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Darrin - KE9NS

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I recently added a simple low res call sign waterfall ID transmit feature to PowerSDR.

EasyPal waterfall ID is the best though.

Darrin Ke9ns.com

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KC8P

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Danny, What is the signal on the left on 14.222? Do you know? I have these too, on 40m is quite strong, every 60Hz...

see this https://www.youtube.com/watch?v=u_2jFgUZ4Mk
(Edited)
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Danny K5CG

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Yes I do know what it is, unfortunately. I operate in purely portable fashion and as such everything runs on a car battery, including the 19V DC to DC adapters that power my laptop. That is what you see there. That garbage sweeps the entire band in an upwards direction non-stop. And now I have TWO laptops with these adapters and a Gigabit switch that are all making noise of one sort or another. I am planning on putting all of those components into an ammo can (with ferrites as well) to try to mitigate all of that.
 
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Duane, AC5AA

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How do other people's signals look?
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K0UNX

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Looking at his first graphic, I see two other signals that don't have that cross-hatch problem.  That station probably has a lot of noise on that antenna as well.  The graphic below shows me switching antennas on the same frequency.  The TOP antenna has a LOT of signals every 10 KC and NOISE.  The other antennas don't see any of that.  I have a common mode filter on order to cure that one antenna.  
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KC8P

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Ok, I see this mostly on 80m, random stations, random patterns......a few minutes ago:

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K0UNX

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If you have another antenna, even for a different band, whether those patterns will disappear.  If so, then the antenna is introducing them, just like my one 15M antenna is doing.
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KC8P

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Forgot to mention, I've tried 3 different antennas, inverted V, vertical and K9AY.....same pattern....
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Darrin - KE9NS

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Are you referring to the "Barber Pole" artifact on the waterfall?


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Rev. David E. Hamm, K4EET

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Here are some webpages to get you started with signal identification:

http://hfradio.org.uk/html/digital_modes.html

http://www.kb9ukd.com/digital/

http://www.sigidwiki.com/wiki/Category:Amateur_Radio

http://wb8nut.com/digital/

And to the poster that said he saw letters, yes, I have seen that too as well as images. You were not imagining things...

73, Dave K4EET
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Ross - K9COX

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Phone home
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Paul

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Hi, the patterns posted by Mario could be aliens or, more probably, due to frequency selective fading. It depends on the state of the ionosphere between the tx and rx antenna and causes different frequency components within the transmission to suffer periodically varying amounts of attenuation.
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pa0bie

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This is the right answer. I have this always on 80m dependant on the distance to the other station whe we are working with FreeDV.
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Jim, KJ3P

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I agree that this is the correct answer.  I have seen the phenomenon when the "ripples" were deep and slow, and heard the phasing effects in the audio.
(Edited)
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KC8P

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I agree with you guys! This is what I suspected from the beginning. Thank you for your help!
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Martin Ewing AA6E

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The patterns are a propagation effect.  The patterns you get depend a lot on which band you're on (higher bands generally show less effect) and the propagation distance (more effect the farther away you are).  They show up most clearly when you're looking at a broad, flat spectrum digital signal like digital voice.

Technically, the ionosphere's electrons (which reflect RF and enable long distance skip) have density irregularities -- they are more or less bunched up in "clouds", and each cloud acts as a separate reflector.   The pattern you see represents "beats" (interference) between the different reflection paths. It changes with time because the clouds are moving around. You can call it "multipath interference", "selective fading" or "scintillation". 

Stars twinkle, too!  (But not because of the ionosphere.)
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KC8P

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Thank you Martin! It is helpful!
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Mark - WS7M

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I think this is part of my fascination with SDR is that I never before had a radio that could even display a pan, not to mention a waterfall.  The add-on's for those were expensive.

When I look at various bands I see all kinds of stuff going on.  Some is easily recognizable as a human signal other stuff is man-made noise and then there is this other stuff that dances around, perhaps runs up and down the band.

I'm sure it existed when I had my old Kenwood and all the radios before that.  I could just never see it.  I do remember what I used to call "birdies" when I would tune my radio and suddenly hear this constant whistle.  I could never figure out if the radio caused them or something else.  Now I can see them!

We humans for the most part are visual beings.   Being able to see a representation of our RF spectrum has made radio even more fun for me.  I'm not transmitting as much and in fact I get great pleasure out of watching the wave forms of other transmissions.

I still have noise to find/hunt for and hopefully eliminate.  It is new this winter.  I didn't see it in summer. That massive peak just below 14.010 will move.  Most of the time it sits right on 14.030 and as you can see there is some activity there right now that when the peak is in place over that frequency is just hidden.

So I'm finding having SDR to be fascinating to look at all these displays and signals.

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Ross - K9COX

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I've been staring at the SDR displays for over 10 years now and really can't imagine ham radio any other way...honestly.
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Ross - K9COX

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One side of my shack is SDR's and the other side is HQ-170, SX-117, Jonson Ranger II, SB-101 as built in 1967, etc.
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Peter K1PGV, Elmer

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I've been staring at the SDR displays for over 10 years now and really can't imagine ham radio any other way...honestly.
No joke.

I was first licensed 10 years ago (OK, so I'm a late bloomer).  After a very brief stint with a couple of Kenwood rigs, I got an SDR-1000.  It's was the first HF radio I did any serious HF with.

After that is was a 1500 and now I've been using a 6500 for a while.

While I've been a SWL for many years, and I theoretically understand how to play (HF) radio with a dial, I have never done so without using a panadapter.  It's all I've ever really used, and it's all I know how to use. It's kind of... embarrassing, really.  I'm pretty much lost when I can't see the band to pick out a station or an opening.

True story: I remember visiting W1AW a few years back.  They offered to let me operate for a while.  I had to decline... because all they had were radios with knobs!

Peter
K1PGV
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Mark - WS7M

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Peter, we all have to start some time.

I started radio in the early 1970's.  I had a crystal 25w CW transmitter and I spent a month trying to build a receiver but I kept blowing things up so my Dad got me a Kenwood R599.  Great receiver but dials only of course.

I had 3 crystals and I'd tune to my crystal freq and if in use I'd wait.  Meanwhile I'd tune up/down and I heard all these things but never had a clue what they looked like.

I've been through about 6 knob radios and took many noise things as I tuned around to be either radio artifacts, external noise or something atmospheric.  But now that I can see them it is fascinating.
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Walt - KZ1F

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Peter, you deprived yourself of an awesome experience. Back in the mid 80s I drove N1CUZ out to Newington from Scituate RI, where we both lived. That, BTW, is the vintage 1700 white house listed on my qrz page. That was prior to computerized logging so we took turns logging for the other who was OP. Imagine calling cq from Afghanistan, that's what it was like. Stations appeared out of nowhere, in an instant, there where hundreds of them. I can't speak for Bob, who I believe is SK now, but I couldn't write fast enough to stay ahead of him, when I was logging. Do it!

Panadapter do add a visual component to the process. For chasing dx, consider a simple listbox of calls in descending order by distance from your qth, independent of band. Upon selection, it would lock your rcv on his xmit and position your TX the appropriate offset plus clear freq. I think there are use cases where a pan might be superfluous.

My first was an hw-101, I had the pleasure to build myself. Both building and operating where hugely rewarding experiences.
(Edited)
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Walt - KZ1F

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Or an app that presents contacts greater than some distance away where you either don't have that qth or that qth on the band they are active on.