Glider Reflections on VHF 2m WSPR

The latest foray on to 2m could not have come at a better time, first the Stations available for signals, second the Aircraft activity and third the Weather conditions.

I always keep an eye on the sky over my QTH, we are ideally sited, only a few months ago the only flying Vulcan played at the end of our road, it was the turning point for an impromptu displaying at Sywell, here he was joined by the local Flying Club boys and Pit Special Display Team assembling at his wing tips, when he flew off home he flew down our street.

On the 9th of June we were not testing on 2m when the Dacota of the Battle of Britain Flight flew low over my garden, probably hopping his was home from the D Day Celebrations.

On the 12th of June again we had stopped the test when the biggest Aeroplane in the world flew what looked like low, yes, over my garden. The Antonov 225 was en route to East Midlands Airport. I didn’t get a photo, there is one on Wikipedia.

What a reflector that would have made.

Earlier in the day we were having some success with 2m DX WSPR and some local Via Aircraft Scatter WSPR decodes, (Bingo Sessions).

Then came this Capture from my Omnidirectional Antenna of the WSPR from G8EUX.

A sine wave? Was an Aircraft continually circling on the signal path between G8EUX and G3ZJO. Well I had noted a clutch of 5 Gliders around G8EUX QTH. And took a Grab.

They headed North and later took the same(very similar)course back to Basingstoke, again when they flew South I captured sine wave reflections an again spotted the likely culprit.

Later I Plotted the EUX – ZJO path on Google Earth.

I then transferred that line to the close up of the gliders path.

No cheating here, the map detail is different and on a different scale, there a couple of lakes NNW of M1 J15A, a good index point on the signal path. Interestingly the Gliders circled in thermals both on their way North and on their return. Yes they circled over Sainsburys Weedon Road. There is an awful lot of tarmac at Sixfields and Westgate Estates and Methane still being released from the waste landfill which was dumped there when I was a lad too.

This raised some thoughts, do wood / plastic Gliders reflect ie show up on Radar. Google it, yes they do.

VHF Radio 2m WSPR Helicopter Reflections

I have seen claims online that traces of direct signals with clean straight lines creating an X centered on the trace are due to Helicopter reflections, I can never get to understand what the theory of these lines going back and forward in time represent or where they came from.

Today I heard but didn’t see what I am fairly certain was a large Helicopter which overflew my QTH and crossed the 2m path between G8EUX and myself.

I looked out of the bathroom window for the Helicopter but it was not in the field of view of the window, I didn’t run outside because I was naked, wearing only a Father Xmas beard of shaving foam.

Luckily G8EUX was TX’ing at the time and I got a nice Capture.

I have left the capture full size for detail Right Click and select View Image for full size view.

Is this not a Capture that stands up to analysis. The Helicopter is approaching me from the East South East and crosses the South to North signal path just as the WSPR transmission ends. There are seven main extra reflections of the signal to HF as the Rotor Blades rotate toward me and seven LF of the reflection as they rotate away. Some weaker reflections can also be seen.

Seeking Wing Tip Vortex Reflections on VHF 2m WSPR

Recently I was introduced to the theory that Vortex’s from Aircraft wing tips can produce reflections on 2m. The 2 Vortices, being contra rotating it is suggested that the reflected signals would be shifted HF and LF of the original.

This capture is proposed as an example of a possible Wing Tip Vortex with a WSPR signal.

It is proposed that there is a possibility that Aircraft need to be landing to produce WTV, however the example above does not prove that it is a landing Aircraft.
G8EUX and G3ZJO are ideally positioned for tests with some strong signals between us and a multitude of aircraft overhead which may detect WTV’s.

A long session on the 7th of June showed no examples, hopefully, we will have some more attempts in the next day or so.

One thing I noted during local tests with my own signal, trying to simulate Aircraft Reflections by transmitting a low level signal near an on air stray modulated carrier was the danger of mixing and overload from strong signals.
My Icom IC706 knows only too well how to produce inter-modulation products, when used for RX it produced different patterns for almost every transmission, once, not repeated as yet I captured this example.

There are some remarkable similarities between the two captures, my IC706 will not be used in any further tests.

OK I continually give the IC706 bad press. So lets look at my 2m WSPR signal from my Beam, first the IC706 with no antennas at all in the rig.
Next the FT897 with a Co Linear antenna on the same mast as the TX Beam plugged in, please excuse the drift it was just switched on, of course there were no adjustments to sound card gain or anything else just a plug swap. The FT897 set up produced the ‘personal radar’ capture in a previous post.

One Spot up to now today on 2m WSPR, another new station to add to the RX list.

2014-06-10 11:08 DB0XIT 144.493513 -28 -2 JN39mi 5 G3ZJO IO92ng 643 303

2 meter WSPR to Paris

Tiring of the links to “How I failed with 2m WSPR” I decided to try some again.

I have been running some Aircraft Scatter tests using just 2Watts to my 8 Element Yagi, to confirm previous experience that WSPR is possible using Aircraft reflections.

Now for a bit of direct QRP 2m WSPR. Some French stations were listed as so I put the beam in the general direction.

I was first to decode F5PXK at 15:42.

Right Click on Images and select View Image for full size.

An example of his signal, which didn’t decode is in the capture.

Then 15:46 started a series of decodes of my couple of Watts.

F5PXK is near Paris, 486 Km

Then followed some Spots from G4SMX at 198Km

A very pleasant afternoon on 2m WSPR.

WSPR 2m Personal Radar

This capture was a surprise. I transmitted WSPR at 144.490530 1 Watt to my Co Linear Antenna I was also monitoring the transmission using an 8 Element Yagi.
Reflections of my signal from 3 Aircraft can be seen.

The pair of images at +/- 100Hz spacing must be ignored they are the normal sound card responses or TX, RX artifacts that we see with WSPR.

VHF Aircraft Reflections on 2 meters WSPR

Tests on the 8th of June 2014 produced a nice WSPR decode from an Aircraft Reflection of my signal on 2m, 21:54 -26dB with a -4 DF.

The deliberate set up was intended to produce a Parallel Doppler reflection.

The result took longer than we usually wait on 6m and one path from a known successful hot spot produced no results, low power (1W) on 2m may not be strong enough for the distances involved.
The Bingo moment signal below.

The Database entry at 21:54.

As usual thanks go to G6AVK for providing an RX station on the right frequency and with the required capabilities.