Friday, July 26, 2013

WSJTX v1.1 - JT65A and JT9 in the same package

A week or two ago, Julian G4ILO blogged about a new version of WSJTX that he'd been testing with Joe K1JT (incidentally, great to see that Joe will be at the RSGB's Convention later in the year) that supported both JT65A and JT9 modes. At the time of Julian's blog posting, the program wasn't publically available, but when I checked earlier this week, it was there and available.

The rather nice idea is that if you have a receiver with a filter that's 4khz wide or so, you can place your receiver strategically so that it can receive both JT65A (say around 14.076Mhz) AND JT9 (up around 14.078). You can decide whether you will monitor both modes or just one. And when you double click to reply to someone, the program determines which mode they were on and transmits accordingly.

I downloaded the program yesterday and had it monitoring away happily in rather poor HF conditions.

More great software from K1JT!

Thursday, July 25, 2013

A 10GHz receiver using an LNBF and an RTLSDR - 10GHz RX for £20 or less?

Laurent F6FVY tweeted the other day a very interesting link, showing that people had used a LNBF designed for broadcast satellite reception and an RTLSDR dongle for 10GHz reception.

There are two good videos and I particularly liked the one from EA5KGD showing his reception of EB5EA's 10GHz signals using the LNBF and the RTLSDR as an IF on around 618MHz.

So, I've ordered a suitable LNBF from the USA, which came in at just over £14 including shipping. If I can get a 10GHz receiver going for just under £20, I'll be happy!

The only puzzle I have at the moment, which I am sure is easily solved, is that the LNBF requires its power to be fed up the coax. I am not sure what arrangement to use for this in conjunction with the RTLSDR. If anyone has seen anything suitable written up, I'd be very grateful! It looks like I need to find a way of feeding the 12V up the coax...

This looks like it would be fun to get going. There's a 10GHz beacon on Cleeve Hill about 40 miles from here. I wonder if I could receive it and potentially look for rainscatter.

Wednesday, July 24, 2013

Readymade antenna adapters for RTLSDR dongles

I'd made up a cheap and cheerful antenna adapter using a spare connector for the RTLSDR dongle, but I hadn't been overwhelmed with its performance. I suspect it was a bit lossy!

When I was reading up on something the other day, I discovered that the antenna socket on the RTLSDR dongle is an MCX connector, of which, I confess, I had not heard previously. In the course of my investigations, I discovered that MCX male to SO-239 adapters are available readily (and pretty reasonably priced) on Amazon

The adapter arrived yesterday and I hooked the RTLSDR up to the 50/144/432MHz collinear. I ran up SDR# and it worked well. Happily there was a 50MHz Es opening going on at the time and I heard several LA stations on CW and SSB. On 144 and 432MHz, the performance was definitely better than my rather lossy arrangement. Airband too was working much better than when I'd tried it before and several transmissions were easily identified on the display.

A small but worthwhile investment.

Sunday, July 14, 2013

Receiving SO-50 satellite signals on the UV-5R and NA771 antenna

During the week, I noticed that there were some good, overhead SO-50 passes in the evenings. The weather has been so good we have often been out in the garden later on. It's been very simple, therefore to take the UV-5R and the NA771 antenna out into the garden and have a listen for the SO-50 satellite as it passes over.

Results have been good, with a number of stations received, including ES6DO, DG0BBE, DL9ZAD (who almost heard me!) and OM0AD. I am sure it will be possible to make a QSO when the conditions are right.

The FT817 and Elk gives much better results, but of course, the advantage of the UV-5R/NA-771 combo is that it is available very quickly and does not require any setting up!

Saturday, July 13, 2013

Tracking flying things: decoding SSDV pictures from 30km high

This morning Dave Akerman launched another of his HAB flights from Brightwalton, a few km to the south of me. For the first time since I have been tracking the balloon flights on 434MHz, Dave's payload was taking pictures and sending them back to ground. Several transmissions from two balloons were available, and as the balloons rose to about 10km, I just tracked their position and altitude.

Then I wondered how I would get on decoding the data and pictures. I tuned the rig to the appropriate frequency and heard an interesting sounding signal. It turned out to be 600baud RTTY. I pressed Auto Configure on DL FLDIGI and was encouraged  immediately to see that data started to be decoded.

Rather pleasingly, on the SSDV Habhub site I noticed my call listed against the pictures that my data packets, which DL FLDIGI uploads to the server, had contributed to. SSDV seemed a very robust protocol and quite often, I would get a solid data packet from the image, where perhaps a position report had failed.

I had not tried SSDV before, but it turns out that if you press S whilst in DL FLDIGI, you can see the image that you are downloading, Here you can see one of the better images that I decoded, when the balloon was around 30km high.

The picture to the top right is the version that I had decoded, with the version on the left the one with everyone's packets contributed.

Once the balloon had burst and was falling to earth, the doppler made the 600 baud RTTY hard to decode for a while, but I was able to start receiving pictures once the payload had slowed somewhat.

An interesting experiment - I like the look of SSDV!

Tuesday, July 09, 2013

WG2XPN 70MHz beacon heard in Europe

Via Dave, WW2R/G4FRE it was good to hear that yesterday, the WG2XPN 70MHz experimental beacon, run by Brian WA1ZMS was heard in Europe on 70.005.

The beacon was heard in GJ, I, DL and IS0 - at a distance of over 7300km. Jo, CT1HZE suggested that this could be as many 4 hops of Transatlantic Es.

Excellent DX!

Sunday, July 07, 2013

Operating G100RSGB, freefalling lions, a few VHF NFD contacts and a satellite SWL!

It's the RSGB's Centenary Year and the callsign G100RSGB has been doing the rounds of the clubs in the UK, a bit like an Olympic torch of the air! Well, this weekend was the turn of the Harwell Amateur Radio Society and they very kindly invited me to come and join in with some operating.

I popped down first thing on Saturday morning. I decided to try some 14MHz CW operation which was modestly busy. G100RSGB is a real pig of a callsign to send on a keyer you don't know. So, after being very gently chided for sending G1??RSDD I decided that perhaps it would be prudent to find another mode!

We got the 50MHz station setup and although there was no Es around, it was fun working some tropo contacts on the band, including a number of stations setting up for VHF NFD. I was particularly impressed to work DJ6XV and another of the team worked a GM/P. On 144Mhz, Ann found some propagation to the south, working an EA1 portable as well as some French stations down in IN93.

Mike G8CUL gets the G100RSGB station at Harwell ready for some DX!

It was great fun to join in with the celebration and many thanks to the Harwell club for the very kind invitation.

In the afternoon, I made a few 50MHz VHF NFD QSOs, I was particularly pleased to work EI9E/P and GW2OP/P - not bad tropo with my vertical antenna - so definite 'Golden Ears' awards for the operators there for pulling me out of the noise.

By chance, later in the afternoon, I noticed that Dave M6RPI had launched another pair of balloons, one of them, once again, carrying Kingsley, the Reading FC mascot. It was fun to track the ascent of the balloon, and noticing the temperature figures reported, showed very clearly that a temperature inversion was going on. One moment the temperature was around -17C and then another 10000m higher and the temperature was just above zero.

It was fascinating to listen to the balloon transmission and for the first time, I was monitoring when the balloon burst. It was quite apparent as the steady signal suddenly started Doppler shifting as the payload fell at around 1km every 15 seconds. Poor Kingsley the lion! But have a look at Dave's video of the balloon burst and see some stunning video footage

Video courtesy of Dave Akerman M6RPI

Then today, I was busy writing the PW column which was enjoyable. In odd breaks I made a few QSOs on 70MHz and again was particularly pleased to work GW2OP/P and EI9E/P. I did faintly hear a GM at one stage, but nowhere near workable. Very pleasing on the vertical.

After I'd finished the column and a few household chores, I noticed an FO-29 pass was due. I decided to have a listen and put the Elk antenna together quickly. There seemed to be some FM interference, but it was nice to hear Bob G0FGX coming through nicely. It turns out Bob is close to where my Mum and Dad used to live in Cornwall.

Finally, as I had the Elk hooked up to the FT817, I decided to see what I could hear and work with the Elk, handheld in the back garden on 144MHz in NFD. I was delighted to work GW2OP/P (again) and even more surprised to work MM0CPS/P in IO84. More Golden Ears awards, fellas!

A nice varied weekend's radio!


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