VHF/UHF WSPR Waterfall images

[VK2OMD]

The freq difference is 36Hz, same callsign... so it looks like the same tx being recieved by two paths with some relative Doppler shift. 36Hz is not a large Doppler shift at that freq.

The quite small change in the Doppler on each signal might be explained by two aircraft travelling the parallel lanes and about the same position along the path to give similar but opposite shifts.

If you watch the Flightradar, you might find scenarios where that might happen, and observe what you see on WSPR (if someone in the right place is transmitting that interval).

Leigh shows a similar observation in a post just prior to this.

Owen

More often than not, the parallel traces on strong(ish) signals is due to overload in the computer's soundcard. Easily repeatable.[/quote]

Did you look at the pics? Are you saying you think it is receiver IMD?

Doesn't look like it to me... one signal fades up as the other fades down... enough reason to not be IMD.

Owen

[VK2KRR]

Owen,

I think Alan was talking about STRONG signals causing the image like in VK3MJC's post, not the weak doppler sigs from Jaysons post.

[VK2OMD]

Owen,

I think Alan was talking about STRONG signals causing the image like in VK3MJC's post, not the weak doppler sigs from Jaysons post.

He quoted my response to Jason VK1JA's post asking for an explanation for his waterfall image, my response was about the waterfall that Jason posted, and VK3DXE's comment "More often than not," was made in that context (he quoted my reply)... and it plainly does not apply to that particular case (that context).

Who is VK3MJC that you refer to... I was not referring to a post my VK3MJC, I didn't even see one.

Lack of care in reading, understanting and quoting posts just makes for confusion and I am sure my original comments are now wasted by the following posts.

Owen

[VK3DXE]

Owen, my apologies. I obviously did refer to the wrong post (trying to do too many things at once), however the subject of AE doppler on WSPR signals has been covered quite extensively in this and other threads. We have, however, recently had a number of relative newcomers querying the multiple traces caused by strong signals overloading onboard souncards.

I find it kind of amusing that you make mention of my "failure to read and understand" when the post by VK3MJC is directly below that of Jayson.

[VK2OMD]

...

I find it kind of amusing that you make mention of my "failure to read and understand" when the post by VK3MJC is directly below that of Jayson.

Yes Alan, that is my error... I even searched using the Find but for some reason did not find it.

If to err is to be human, I can be very human!

Yes, although there is only one product visible in VK3MJC's post, it does look suspiciously like sound card clipping (overload), a difference phenomena to VK1JA's pic.

Owen

[VK3DXE]

...

I find it kind of amusing that you make mention of my "failure to read and understand" when the post by VK3MJC is directly below that of Jayson.

Yes Alan, that is my error... I even searched using the Find but for some reason did not find it.

If to err is to be human, I can be very human!

Yes, although there is only one product visible in VK3MJC's post, it does look suspiciously like sound card clipping (overload), a difference phenomena to VK1JA's pic.

Owen

Very definitely a product from within the soundcard Owen. The lower one is outside the WSPR passband.

[VK2OMD]

...

Very definitely a product from within the soundcard Owen. The lower one is outside the WSPR passband.

That highlights a difference in our approaches, You KNOW the invisible product is there, I only suspect it is likely.

Owen

PS: This is a sidetrack, VK1JA's is not likely to be IMD, and I think we are all agreed on that Jason.

[VK3DXE]

I know it is there because of extensive experience in observing just that. I ALWAYS have SpecLab running whenever the radio is on, so I observe this and other effects regularly and am able to see signals outside the WSPR passband. The strong frequency and amplitude correlation also supports my statement. There is a strongly doppler-shifted trace across my signal in the 09:22 and 09:24 blocks.

Jayson's (there is a "y" in his name ) post certainly appears to show a (most likely AE) doppler shifted secondary trace, as indicated by the variation in drift between the two traces. The primary is also most likely aircraft enhanced and showing some doppler shift as I believe both stations are GPS locked, although this doesn't discount frequency instability issues in the soundcard. I believe Leigh has started a thread dedicated to recording those stations that are locked and their regular TX frequencies.

If Jayson's observation is of 2 doppler shifted signals with such a small frequency differential, then I would suggest, again from experience, that he is observing 2 aircraft on the same flightpath (which is slightly oblique to the direct path between the stations) with a separation of several minutes. There appears to be subsequent slight difference in angular velocity of the 2 aircraft with respect to Jayson which may be accounted for by their relative positions on the flightpath, altitude or groundspeed. I hope I'm making sense, as I am not a mathmetician nor a physicist. I'd find it much easier to represent what I'm trying to relate in a drawing, preferably with crayons on butcher's paper

[VK1JA]

Wow, I've never seen my name mentioned so much in a single thread before!

If it matters at all, for the first 16 years of my life I was known as Jason, and it was only when I obtained a copy of my birth certificate that I noticed my name was spelt with a Y and my parents somehow forgot to tell me....

Thanks for the thoughts on the strange double decode capture. I've only ever seen it once before and that was also with VK3NFI, so it may be unique to the path between VK3NFI and I. If I do see it again I'll fire up Flight Tracker and take a screen capture of what planes are going back and forth. It would certainly be interesting to see how the signal is being affected along the path.

And yes, I believe VK3NFI is GPSO locked, as is my station.

[VK3DXE]

Wow, I've never seen my name mentioned so much in a single thread before!

If it matters at all, for the first 16 years of my life I was known as Jason, and it was only when I obtained a copy of my birth certificate that I noticed my name was spelt with a Y and my parents somehow forgot to tell me....

Thanks for the thoughts on the strange double decode capture. I've only ever seen it once before and that was also with VK3NFI, so it may be unique to the path between VK3NFI and I. If I do see it again I'll fire up Flight Tracker and take a screen capture of what planes are going back and forth. It would certainly be interesting to see how the signal is being affected along the path.

And yes, I believe VK3NFI is GPSO locked, as is my station.

I see some pretty interesting doppler patterns from my QTH, particularly with the current really broad antenna, as I have a decent view from the east right around to the west, which takes in most Melbourne airport approach/departure paths. Its really quite interesting watching and interpreting the movements of various aircraft in this manner. I can usually identify exactly which each one is on FR24 by correlating +ve or -ve doppler, turns, etc. Even the kids find it interesting.

[VK2KRR]

Interesting AE doppler signal from VK1KW this evening -

AE doppler from VK1KW signal

The other weaker station further to the left, also with an AE doppler signal, I believe is Brian VK5BC.

[VK2KRR]

Tim on 1296.

VK3JTM 1296

[VK3ZAZ]

RMV at 30K is strong and blacks out whoel screen

WSPR is not meant to work on such strong signals
IMO no point, so drop power

RMV at 5 watts is within the limits of some stations and outside the limits of other poor stations or poor paths to stations

[VK5ACY]

The (your !) VK3RMV beacon is always audible here via tropo and it's interesting to watch the QSB via WSPR.

VK3RMV bcn, tropo at 352km, several sessions.

Steve:- Thanks for a reliable signal source - your rig is very stable.

[VK2KRR]

Captured this screen shot of what Alan VK3DXE's signal looks like this evening from multiple aircraft and drifty signal in the beginning. I was beaming near VK3JTMs heading and Alan is reportedly beaming at VK1.

VK3DXE 2m 10.04.14

[VK2KRR]

A nice sample of meteor pings from Frank VK5KV on 2m WSPR this morning from Port Augusta SA.

VK5KV Pings

[VK2KRR]

Got a large aircraft reflected signal from Peter VK5PJ followed up next period by Andy VK5LA also with number of aircraft signals.

VK5PJ VK5LA with AE

[VK2KRR]

Was somewhat impressed by the following decode of some very weak partial signals I received Perrin VK3XPT running 2 Watts and was on the side of my 2m array.

Weak VK3XPT signals decoded

The 547 Hz is direct and the 539 is aircraft reflected. Not a great deal of signal in there during the 2 min period.
(also the weak signal shown in the current period is a brief look at VK5VF beacon)

[VK5ZRL]

Hi all,
here is a screen capture of a possible aircraft doppler wspr signal from VK5LA.
The reason I suspect it is from VK5LA is that Leigh VK2KRR decoded his signal
at the time (too much doppler for wspr to decode here).

2014-07-27 01:30 VK5LA 144.490515 -5 QF05gq 10 VK2KRR QF34mr 603

[VK3ZAZ]

The (your !) VK3RMV beacon is always audible here via tropo and it's interesting to watch the QSB via WSPR.

VK3RMV.jpg

Steve:- Thanks for a reliable signal source - your rig is very stable.

Thanks Bill
I recently sold my cheap laptop
and the emachine freezes up,'
when I went to clean my laptop up I realised I had left the auto store on and had filled the harddrive 65M with 61 Meg of loggings
Makes me wonder what becomes of all the cyber babble
It is unlikely I will set up again unless I find a cheap PC as we don't have internet for time stamping only the USB satellite receiver.

I must profess to be waning in my interests in ham radio, prob due to old age.

I enjoy my shed and my old cars.
My wife says I am in my element.


WSPR needs to get us to the next levels something NEW
That we don't already know don't you think?

ZAZ