G8TTI's Notebook

Powersdr skins

david — Sun, 15 Jan 2012 20:37:18 +0000

Here are some Powersdr skins I made up using graphics from W1AEX.

Looks like a microwave oven!

DM0DUB

david — Thu, 08 Dec 2011 21:46:29 +0000

DM0DUB received in IO81WM 08/12/2011

Received here today under unusual conditions i.e. weather wind and rain. DM0DUB is located in JO40AQ a distance 713km from IO81WM.

Tropo S meter recording of GB3VHF

david — Sun, 04 Dec 2011 20:45:40 +0000

Here is a recording I made yesterday morning of the signal strength of the GB3VHF beacon which is located in Kent JO01eh as received here near Chippenham IO81wm. It usually hovers around S6-7 here but there was a clear enhancement yesterday morning. Doubtless more distant repeaters and stations than normal where heard on FM.
The line on the graph is the signal strength of the beacon (-60dBm is S9+10db approx) time goes right to left so the recording starts at 1140 ends at 1211.
Weather at first was fog with rain arriving round-about 1145 and then getting more persistent.
I think that the drop in conditions is very apparent.

Gradual fading of the beacon signal

Towards the end of the recording signal strength is bumping along at S5-6 (-90dBm). It’s also a lot less stable than earlier.

The regular dips in the trace at the beginning are the WSJT tones sent by the beacon which produce a slightly lower average S meter reading.

This image shows the beacon increasing in signal strength.

Here is the link to the GB3VHF website and more info on this propagation report.
http://www.gb3vhf.co.uk/GB3VHFusingthebeacon.html

Hardware homebrew 144Mhz SDR – Software SDR-Radio by HB9DRV

DB0FAI via Meteor Scatter

david — Mon, 15 Aug 2011 07:42:41 +0000

This is a recording I made of DB0FAI using my home-brewed two metre hybrid SDR, Powersdr-iq and Radiosky-pipe on the 13th August 2011 at 1654utc.

Signal received via MS with a burst long enough to hear the full callsign of the beacon.

Download file here

db0fai_110813165434
Or play here

Here is a shorter burst from DB0FAI recorded using Rocky and RadioSky-Pipe.

Short burst from DB0FAI

You can read about the beacon here http://www.qsl.net/db0fai/

OIRT FM broadcast on the 70MHz four metre band

david — Sun, 07 Aug 2011 20:16:15 +0000

This video was made in July 2011 and shows an eastern European OIRT FM broadcast station being received in the west of England on the 70MHz four metre amateur band.

The water fall display and demodulation is by HDSDR with the frequency control and panadaptor by Powersdr-IQ (audio swap has been used but this is very much the type of music being played).

Audio swap was used as I wasn’t sure about the copyright of posting a broadcast station sound on Youtube but lots of other don’t seem to care!

Azores beacon CU8DUB

david — Thu, 19 May 2011 03:37:08 +0000

If you’d checked the Hepburn VHF Tropo forecast on the 15th May you would have seen the extended ducting from the UK out into the Atlantic.
This enabled the reception of the Azores beacon CU8DUB on 144.420MHz here in North Wiltshire at a distance of 2600km which is half way to North America.

The signal is not strong but I’m some way inland in that direction unlike the people in Cornwall and on the south coast that also reported it and had contacts.

The other beacons are GB3VHF (Kent) at the top, just beneath CU8DUB is a faint trace from ON0VHF and a stronger French one at the bottom. The vertical lines are the farmers electric fence!

Hybrid SDR

david — Sun, 15 May 2011 11:14:59 +0000

Not added any thing new to the site for sometime now but hope to get a page together for a new hybrid SDR I’ve built in the near future. Transmits only on two metres at the moment but has wide ranging receive i.e. 0 to 200MHz. Check back soon.

CW Contest and Propagation

david — Sun, 07 Nov 2010 20:40:22 +0000

Three screen shots from this weekends 144MHz cw contest. The first one shows a considerable MS burst resulting in many reflections from contest stations throughout Europe. I’ve high lighted the burst and an earlier ping within the the rectangles but I think they are pretty obvious.

Images click to enlarge

The second one shows a clearly multi-pathed signal from a G station. I have no idea why this results in the four or so images of the main signal, not seen in this screen shot but sometimes the signal is all but lost in the reflections.

Lastly, back to MS, a close in shot of a short ping. The tail is the ping!

The Shack

david — Sun, 31 Oct 2010 21:16:18 +0000

From April to October I have an outside shack. It’s just a wooden shed. From November to March I have an inside shack. Outside is best but during the Autumn and Winter months the weather turns too cold and the days are short so I move inside.
The only problem with this is that the antennas are 200 feet away. So I have two lengths of coax that run to the outside shack, where a Two metre amp, which is rf switch, is connected to the lower loss cable. The other length of coax, which is slightly more lossy, I use to connect to the various low VHF and HF antennas as my fancy takes me.

Here is the inside shack, hardly a radio to be seen! But what you see covers HF, Six, Four and the Two metre band.

Well there is more of course and its underneath an old coffee table along side the computers.

Cheers

(I know no one will every bother to read this, it’s just that there’s nothing on the radio. Well if I’m wrong prove it and post a reply).

Dave

Two metres, a dead band?

david — Thu, 21 Oct 2010 07:01:44 +0000

You can never tell when something interesting or unusual may happen on VHF. Yesterday morning I was in the shack putting together a DK7ZB long boom yagi with the home-brewed SDR running on 144.300MHz when up popped a station calling CQ. Not sure what the call sign was at first but it didn’t sound like a G so listened more intently and managed to pick up the call UT1–/MM who was in the English Channel JO00. Tried several calls but no joy although a well known station near the Welsh border worked the /MM without to much trouble. Tried again, the signal was fairly strong S5 or so but still no joy so I gave up. Perhaps he had a high noise level or something.
After that I returned to monitoring and busied myself with the construction of the new yagi but almost immediately I heard another station calling “CQ CQ two metres I4B–” 59+ this one! A frantic grab for the mic “G8TTI OVER!!”, he’s come back to me, no he’s working someone else. Tried a second time, no joy he’d faded into the noise. No sure what the propagation mode was, probably a mix of MS and Es, six had been open the day before and when I checked DXSherlock six had been open at the same time in central Europe.
Just bad luck that I didn’t work either station but it provided some unexpected excitement on what was an otherwise dead band.
73
G8TTI