How to read the waveforms

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  • Updated 4 years ago
There are a lot of smart guys on here, so I hope you don't think my question is dumb. But, here goes.
Looking at the top waveform in the slice. When I'm on SSB (let's say USB), the display shows a yellow line for the frequency I'm on, and the waveform starts from there going left to right. Is the wave closest to that line the low frequencies, and those going away getting higher? Is it the opposite for LSB? Also, the wave in the waterfall, is that created left to right under the same scenario? When I tell guys on the air I have a Flex radio, many have asked me what their signal looks like. I'd like to give them an intelligent answer.
I've been in radio since the 60's, but nothing like this. Thanks in advance for your patience and advice.

An old dog trying to learn new tricks.
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Bob - WD8KND

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Posted 4 years ago

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Jim, KJ3P

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You've got it correct, Bob.  And yes, it's the opposite for LSB.

Note the little "blank spot" between the yellow line and the start of the signal waveform (actually the "waveform" is your listening bandwidth).  This shows the lower audio frequency cutoff of your receive bandwidth, often between zero and 100 Hz (common setup, but variable with Flex).  The far end of the bandwidth might be, say 3000 Hz away from the yellow line, indicating that the received audio can extend that far.  Sometimes you'll see the person's audio stop short of the bandwidth, other times perhaps go beyond the bandwidth.  You can see how the received station's TX audio is set up.

I remember hearing/seeing a big notch in one station's audio around 1000 Hz...he sounded a bit hollow.  I asked, and we found that his TX equalizer was mis-adjusted.

Flex = cool stuff!

73,

   ---jim KJ3P
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Bob - WD8KND

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Jim,
How do you read the frequency spacing of that blank spot you referred to? How do you know if it's 100 or 400?
Thanks,
Bob
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Joe, KQ1Q

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Yes on USB the RF passband goes from L to R. The lowest frequencies are on the left. For a 3Khz passband this roughly corresponds to audio frequencies from 0 to 3000 Khz. Yes LSB is the opposite.

Yes the waterfall below the panadapter display corresponds exactly in frequency to the waveform above. The difference is the panadapter waveform indicates signal strength by vertical amplitude, whereas the waterfall indicates this by color coding.  

In general the more intense colors correspond to higher modulation. However unlike many other (maybe all other?) waterfall displays, Flex sends over raw data not a graphical color. This means the final interpretation of the waterfall color is determined on the client, and can easily be changed. E.g, you can grab the vertical time scale on the right side of the waterfall, roll it back and halt the display -- yet in that state you can press the Display button at upper left and change the gain, black level, etc.

If somebody wants to see their waterfall, it is easy to take a snapshot using Shift-Print Screen (hold down the Shift key then press the Prt Screen button). This copies the current display to the Windows clipboard. You can then run the Paint program and paste that in using CTRL-V, then save it as a .jpg file to send or upload.

If the image is too big for easy email transmission, a good easy-to-use resizer is this one: https://imageresizer.codeplex.com/

- Joe, KQ1Q
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Bob - WD8KND

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Joe,
When looking at the waterfall, a good strong signal looks very squared off. Some strong signals, however, have bursts that are coming out of the square to both the left and right. Are these bursts splatter?
Thanks,
Bob
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Joe, KQ1Q

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The edges of an SSB waterfall should be relatively clean. The spikes and other stuff sticking out is splatter. It can be caused by various things: audio gain too high, exciter input to linear amp too high, EQ set wrong (typically over boosted on lows), SSB balanced modulator out of adjustment, etc. 

On a time-domain display like an oscilloscope the signal may not look so bad. But clipping or distortion can have severe ramifications in the frequency domain, typically increased bandwidth. In past decades we could only indirectly experience that by hearing the splatter, but with high resolution waterfall displays it is visually apparent. 

In most cases if the operator would just use the simple procedures in the manual to adjust his rig, the splatter would not happen or be greatly reduced. A scope, spectrum analyzer or exotic procedures are not needed.

It is tempting to tell operators with severely malformed signals, but it's not like a waterfall display was the first indication. Sometimes other SSB stations cannot get within several Khz without getting splattered. No receive filtering can really handle this because the splatter is RF within your receive passband.

The Flex 6000 waterfall display has such high resolution that signals can be examined in great detail. E.g, see these AM signals from the commercial broadcast station WSM: http://joema.smugmug.com/Hobbies/Ham-Radio2/Flex-Radio-spectral-captures/49459236_qqfs4c
(Edited)
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Jim Hawkins / K2JHV

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Also, on some signals, you will see not only the signal, which extends from the 100 HZ low end to the 3kHZ high end, a slope of ragged signal on either side of it.  Those slopes are harmonics or "splatter", usually caused by audio over drive.  Often a 3kHZ station will be almost 9kHZ wide because the splatter on either side of it is an additional 3 kHZ.  This is not to be mistaken for a clean wideband SSB signal you might see, say on 14.178.  I have gotten to the point where I can actually recognize the person by the spectrum and get it right 80% of the time.  I might see a signal I am not tuned to and think "Oh, I'll bet that's Bill."  AM signals will have a "spike" in the middle of the lower and upper sideband, which is the carrier.  There are lots of other types of signal you will get to recognize like the FDV or plasma TV interference.

I often take screen shots of someone's signal spectrum and email it if they request it.  I use Paint Shop Pro, but there are other ways.
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Joe, KQ1Q

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I forgot to add, instead of doing Shift-PrtScrn, you can also use the built-in Windows "snipping tool" in Accessories to cut out the screen region for saving.

Sometimes it's good to minimize the extra SmartSDR displays to provide more real estate. This includes:

- Pressing the left arrow button on the upper-left controls
- Pressing hide radio panel button at the lower left
- Pressing the slice receiver A or B button to hide the slice flag

You can also click and drag horizontally on the frequency bar that separates the panadapter and waterfall. This changes the span and frequency resolution without pressing the +/- zoom in/out buttons.
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Mark Erbaugh

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Instead of Shift-Print Screen which captures the whole screen, Alt-Print Screen will capture only the active window
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Ken Davis

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Snipping tool in Win 7 and 8 is great. Just bring it up from ACCESSORIES and select Window under the NEW button then click on the Flex window and your done. Click on the SnipIt icon in the bar below and then click on the email icon and you can send the entire window picture.  But, if you really want to show off do a recording of your conversation and play it back to him. That will show him how well you have tuned him in with the Flex. 
"Happy Flexing"
Ken
W0KRD
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Bob - WD8KND

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Thanks all! What a great response! I've printed it all out to read and reread.
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Roy Laufer

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Anyone try "Guess that mode!". AM seems the easiest to recognize on the panadapter and morse code is the easiest  to recognize on the waterfall. I've been able to learn to recognize FM (both digital and analog voice), SSB (both characteristically USB and LSB) and PSK.

Has anyone out there figured out how to recognize other modes on the visual display?

Roy, AC2GS
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Ken - NM9P, Elmer

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CW - a single spike with narrow sidebands pulsating with the rhythm of the code.

BAD CW - similar, but a lot wider, often 500-1000 Hz wide, if it has lots of key clicks, overdriven amplifier, or is being sent by Modulated CW with a soundcard and poorly adjusted SSB rig.

RTTY - is easy, if you are zoomed in a little, it has a characteristic double-hump shape.

PSK31 - looks like a little railroad track on the waterfall

PSK63 - looks similar, but wider and not as "clean."  (as opposed to a dirty PSK31 signal)

FreeDV - has a spike in the middle and about 7 humps on either side of it, totalling about 1.4 KHz wide.  It looks like an overgrown music staff on the waterfall.  Look at 14.236 or 14.240.

WSJT bounces around over about 250 Hz with random frequency shifts.

OLIVIA - looks like a pattern of about 16 different dots stringing out over about 500 Hz width and rapidly shifting in a musical dance, 

I can recognize FELDHELL but I can't exactly describe it....sort of like a single spike with a narrow funnel-shaped sideband on each side as it splut-splut-splut's the graphics signal. 

EasyPal fills the Audio bandwidth with lots of granular, shifting patterns (Look at 7.173  or 14.233

SSTV - Varies according to the SSTV Mode - usually a single carrier of audio at about 1200 Hz with audio sidebands above it for about another 1200 Hz dancing the pattern of the video and color information.

AM - Easy - single spike carrier with audio sidebands bouncing on each side, just like an SSB signal with a mirror image.

FM  - Single spike carrier that disappears and melds into the audio with modulation.  Modulation waveform fills the bandwidth, but width varies with voice amplitude.

Buckshotting or overdriven SSB signal - Wide in the pattern with little sideways spikiness in the waterfall, often spreading 5, 10, 20 KHz each side of the SSB signal bandwidth.  Signal often clean with regular speech, but suddenly widens out on voice peaks or when the station is losing the pile-up war and talks louder, thinking that it will get out better that way.

The best way to learn is to listen to various signals, and watch the panafall until you train your eyes and ears.  Before long you will recognize them instinctively.

There are others, but I can't remember them right now.

Ken - NM9P
(Edited)
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Jim Hawkins / K2JHV

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That's a nice list, Ken.  I saved that for reference.  Some digital signals begin and end with text on the panafall.  What type of signal is that?  I assume what ever app or equipment has that feature built in.

By the way, I call the sigs with the splatter "Chimney Rock" signals...like the one in Nebraska.

Jim - K2JHV
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Ken - NM9P, Elmer

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The signals that begin & end with waterfall text are often EasyPal, digital SSTV signals.

Have fun.  Adding the visual dimension to the rig really adds to the experience.  Like you said, I can sometimes recognize someone from their "voice pattern" without even having the audio turned up.  (Especially if I am on or near their usual hang-out frequency.)
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David Altekruse

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RTTY, JT65 and JT9 digital modes are very easy to recognize.  I'm guessing almost all modes are easily recognizable to those who use them.

In my opinion, it would be helpful if all hams became familiar the signature of all legal modes or at least the difference between noise and a mode.   I'm surprised and disappointed in the number of hams who transmit on one digital mode right on top of another QSO on another mode.  I hope it is because they think it is just noise since they can't decode it.  I'd hate to believe any ham would intentionally wipe out an on-going QSO.
(Edited)
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Jim Hawkins / K2JHV

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One of the advantages of the new panafall rewind is that, not only can you see if the frequency is in use, you can rewind it to see if it has been in use recently by scrolling it up in time.  I would like to see my transmission recorded as a new feature on the panafall, so I can see how longwinded I've been.  I can do it now by recording it on Audacity via DAX.
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Joe, KQ1Q

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You can sort of do that right now by enabling "Show TX in Waterfall". It is in Settings>Radio Setup>Transmit. After transmitting you can grab the vertical time scale on the right side of the waterfall, scroll it back and by comparing the start/end times, see how long your transmission was. I don't know what the buffer limit is, it may relate to the display rate which is set in the upper-left controls.

I just tested my 6300 on a 5 min transmission (to a dummy load), with display rate at 85. I could scroll back over my 5 min transmission. That is probably enough for most people, except AMers of course.
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Jim Hawkins / K2JHV

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Joe,
Thanks for the tip.  I just tried it.  It does exactly what I want it to do.
I've seen the dialog box before, but did not notice the button on the bottom.

Thanks!