WSPR operations on 144 MHz

[VK5ZD]

Interesting!!

I had a similar thing happen here last night. I came into the shack and noticed that VK5KK was being decoded twice; once at 144.490520MHz (correct frequency) and also 100Hz lower at 144.490420MHz.

Signal from VK5KK showing 'clones'.

I checked the WSPR web site and found that this was happening for two of the stations I was receiving (VK5KK and VK5AKK) but not VK5AKM. I then experimented with my signal generator and found that a strong signal would produce 'clones' at 50Hz intervals above and below the genuine signal. As the signal strength was reduced the +/-50hz 'clones' vanished leaving only those at +/-100Hz. I'm now wondering why the effect didn't happen with VK5AKM's signal which was stronger that the other two.

This evening I noticed this strange effect. The 'clone' of VK5KK's signal at 144.490420MHz is only present for just over half the two minute receive period. Nothing has been changed since last night. It's only by chance I came into the shack at the right time to see the 'clone' signal stop part way through the transmission.

Signal from VK5KK showing 'clone' stopping mid-transmission.

The most recent signals received from VK5KK after the last screen shot show no sign of a 'clone'.

I'm wondering (a) what causes this effect and (b) why did it suddenly stop? I suspect that the answer to (b) will become obvious once (a) is known.

73
Iain

[VK5ZD]

Further to my last message, I checked my WSPR log for the last few days.

WSPR_Clone_Signals.pdf

(242.5 KiB) Downloaded 257 times

It appears this phenomenon has only happened during the last 16 hours or so and, even then, it's only on stronger signals and it doesn't happen every time.

Iain

[VK3DXE]

Hi Iain,

What you're seeing is most likely caused by audio levels being too high at one end of the path, usually TX.

If you run SpectrumLab, you should be able to see your own signal, albeit quite faintly, in the waterfall on TX. I've found that if my TX audio level is too high, then I start to get these "spurious signals" too. Knocking the volume control back a little sees them disappear.

[VK3BQ]

I see this on vk3xpt all the time, and sometimes get the double decode on him as well.

ive backed off the TX audio, (last night, i was playing with different settings and computers, the weird event I had might have been me not running the right setup!)

still learning this thing

[VK2KRR]

Andrew I'd say thats just because he has such a strong signal to you, I'd probably see the same thing here if he was +16

[VK3DXE]

Andrew I'd say thats just because he has such a strong signal to you, I'd probably see the same thing here if he was +16

He's strong here too Leigh, but no change even if I attenuate his sig down to nothing.

[VK3BQ]

a couple more silly newbie questions..

where do I set the (usb microphone) level?

and, on the ic9100, i have lots of control of the filtering (all dsp) ive turned off all the processing i can, BUT,, what filter width should I use, default data mode is 1.2khz wide. is this ok?

[VK5LA]

Hi Andrew,
With that setting for the usb microphone I'd set it like this...
Set the signalink RX control to 12 oclock. then set the usb microphone control so that when the rig is listening to no signal (ie just static or atmospherics in USB mode) the RX level in the bottom left of the WSPR screen shows around 3-6db, when actually RXing, not "waiting to start".
I find that this gives the best results for decodes.
For RX, just normal SSB mode is fine. no need for narrow filters or DSP. The WSPR software doesn't need any help!

For TX, make sure there is little or preferably NO alc when TXing. no proccessing, no nuttin'!
On the 910H, the alc indication is the red TX lamp on the left of the front panel. It's brightness is your alc.
I set mine as follows...
Set the rig for full output. TX control on signalink to 12 oclock. TX a signal, adjust computer soundcard output slider so the red led starts to go dim and the output begins to drop of a bit...
Now wind back your power to a more wspr friendly level, your tx will be clean.
Hope that helps
Andy - VK5LA

[VK5LA]

I see it's a 9100 not a 910H, hopefully that has alc metering!!!

Andy - VK5LA

[VK5ZD]

Hi Alan

What you're seeing is most likely caused by audio levels being too high at one end of the path, usually TX.
If you run SpectrumLab, you should be able to see your own signal, albeit quite faintly, in the waterfall on TX. I've found that if my TX audio level is too high, then I start to get these "spurious signals" too. Knocking the volume control back a little sees them disappear.

In this instance I think this is an unlikely cause. Obviously my TX level has no effect on what I receive. I observed this effect on signals from two different stations over a period of a few hours. The effect came and went during this time. For the effect to be caused by the TX level being too high it would mean that both the other stations were adjusting their TX levels up and down at the same time. Not impossible, but what are the chances? Small enough to ignore, methinks.

I think it has to be something happening in the receiver; I just don't know what. Why are the spurious signals at 50Hz (or, occasionally, 38Hz) intervals?

73
Iain

[VK3BQ]

crazy local multipathing not helped by my verticle wobbling a little (lot) in the wind + local trees I gather (not under any local flight paths)

[VK3DXE]

crazy local multipathing not helped by my verticle wobbling a little (lot) in the wind + local trees I gather (not under any local flight paths)

Capture.JPG

They're not necessarily "local" aircraft there Andrew. They can be anywhere in your shared field of view with the other station.

I often get interesting results from Perrin, VK3XPT; mainly from planes on final approach to or departure from Tullamarine, but I also regularly see quite strong, and interesting, patterns from planes a couple of hundred km out in the Latrobe Valley. On the Adelaide path, I often see multiple returns, particularly when there are a number of aircraft traveling each way.

I've posted some screen caps previously here: viewtopic.php?f=29&t=9707&start=150#p34458

[VK2KRR]

Circled again Rob.
There also appears to be a much more rapid doppler move through at 0852 period which I think u may have been TX then also, thats just before the TX line I made.

ISS VK1KW

[VK2KRR]

crazy local multipathing not helped by my verticle wobbling a little (lot) in the wind

Andrew VK3BQ, those patterns are not from the antenna moving about, its from planes manoeuvring about in your line of sight field I'd say.

[VK2KRR]

Some exciting stuff this afternoon/evening as Wayne VK2XN near Narrabri, northern NSW was able to make the most of a brilliant high pressure system spanning from South Australia to Queensland and beyond.

Here are some of Waynes spots -
2013-06-04 09:10 VK2XN 144.490482 -26 0 QF59ar 10 VK5AKK PF94ix 1184 km
2013-06-04 08:58 VK2XN 144.490490 -3 0 QF59ar 10 VK5ACY PF95sb 1111 km
2013-06-04 08:58 VK2XN 144.490483 -24 0 QF59ar 10 VK5AKK PF94ix 1184 km
2013-06-04 08:40 VK2XN 144.490485 -12 0 QF59ar 10 VK5AKK PF94ix 1184 km
2013-06-04 08:40 VK2XN 144.490492 -4 0 QF59ar 10 VK5ACY PF95sb 1111 km
2013-06-04 08:04 VK2XN 144.490487 -18 0 QF59ar 10 VK5AKK PF94ix 1184 km
2013-06-04 08:04 VK2XN 144.490496 -14 0 QF59ar 10 VK5ACY PF95sb 1111 km
2013-06-04 07:56 VK2XN 144.490495 -13 0 QF59ar 10 VK5ACY PF95sb 1111 km
2013-06-04 07:32 VK2XN 144.490492 -14 0 QF59ar 10 VK5ACY PF95sb 1111 km
2013-06-04 07:20 VK2XN 144.490491 -20 0 QF59ar 10 VK5ACY PF95sb 1111 km
2013-06-04 06:38 VK2XN 144.490490 -14 0 QF59ar 10 VK5ACY PF95sb 1111 km
2013-06-03 22:42 VK2XN 144.490547 -28 0 QF59ar 10 VK5LA QF05gq 999 km

VK2XN to VK5!

Wayne also reports a spot from Arie VK3AMZ during the previous night.

Well done Wayne and the others involved, Bill, Phil and Andy. Now to get the VK4's to complete a path into the Adelaide area!

[VK2KRR]

Lots of colour on the 2m WSPR map tonight from VK5 to VK3

WSPR Sat Night

[VK3DXE]

Excellent conditions towards Adelaide tonight.

So far total of 7 stations heard here and heard by 10.


0930 -19 -2.3 144.490416 -1 VK3AIG QF12 37
1000 -13 -0.3 144.490465 0 VK5AKK PF94 43
1002 -12 -1.0 144.490482 1 VK3JTM QF12 50
1002 -21 0.9 144.490504 0 VK5GF PF94 43
1004 -7 -0.6 144.490451 0 VK3AMZ QF22 33
1010 -11 -0.9 144.490497 0 VK5AKM PF95 43
1012 -25 1.5 144.490507 0 VK5GF PF94 43
1012 -14 -0.7 144.490520 0 VK3WRE QF31 40
1014 -8 -0.6 144.490455 0 VK3AMZ QF22 33
1016 -13 -1.0 144.490499 0 VK5AKM PF95 43
1036 -7 -1.0 144.490453 -3 VK3AMZ QF22 33
1036 -16 -0.8 144.490470 -3 VK5AKK PF94 43
1036 -9 -0.9 144.490487 -2 VK3JTM QF12 50
1036 -15 -1.1 144.490499 -1 VK5AKM PF95 43
1036 -15 -0.5 144.490521 -3 VK3WRE QF31 40
1100 -17 -0.9 144.490520 -3 VK5AKM PF95 43
1100 -22 1.2 144.490530 -3 VK5GF PF94 43
1106 -6 -1.0 144.490466 0 VK3AMZ QF22 33
1110 -16 -1.1 144.490518 0 VK5AKM PF95 43
1112 -2 -0.6 144.490488 1 VK5AKK PF94 43
1112 -11 -0.7 144.490506 1 VK3JTM QF12 50
1112 -32 -0.6 144.490588 0 VK5AKK PF94 43
1116 -2 -0.8 144.490469 0 VK3AMZ QF22 33
1118 -25 -0.2 144.490542 1 VK3WRE QF31 40
1120 -24 -1.0 144.490521 0 VK5AKM PF95 43
1122 -18 1.3 144.490531 0 VK5GF PF94 43
1128 -4 -0.9 144.490471 0 VK3AMZ QF22 33
1128 -24 -0.3 144.490493 0 VK5AKK PF94 43
1130 -9 -0.5 144.490512 1 VK3JTM QF12 50
1130 -24 0.6 144.490534 0 VK5GF PF94 43
1130 -25 0.0 144.490545 0 VK3WRE QF31 40
1132 -17 -1.0 144.490524 0 VK5AKM PF95 43
1136 -20 -1.0 144.490525 0 VK5AKM PF95 43

[VK4CZ]

Been running on 2m WSPR this morning... some interesting effects of AE on Col VK4MIL... and a very weak trace from Wayne VK2XN (I think)!

[VK3DXE]

Been running on 2m WSPR this morning... some interesting effects of AE on Col VK4MIL... and a very weak trace from Wayne VK2XN (I think)!

Nah, that's a sparrow farting somewhere.

You've obviously reached the practical limit of sensitivity with your system now that you can detect the electron spin from said sparrow farts.

[VK2XN]

G'day Scott,

Beats me how we manage to hear each other at all..