5 MHz NoV

I decided to apply for my 5 MHz (60m) Notice of Variation so I can operate on that band. The process for Full licence holders here in UK was very easy and all I had to do was to fill out an on-line form on the RSGB (www.rsgb.org) web site and the NoV was emailed straight back to me.

I have not been on the air yet but spent some time listening This is a complicated band so I thought I had better get to know it before transmitting.

Sked anyone?

73 Dave

Software Defined Radio (SDR) - First Steps

I have often seen adverts in the amateur radio press for Software Defined Radios (SDR) and wondered why they are so expensive. During a discussion at my radio club (Cray Valley - www.cvrs.org), I learned that a TV/Radio Dongle receiver can provide the hardware for SDR. I found a suitable dongle (RTL2832 plus either R820 or E4000 chip set) on Ebay; ten UK Pounds from Hong Kong so, being the last of the big spenders, I went ahead and ordered. While I was waiting for it to arrive, I downloaded a copy of SDR Sharp  (SDR#) and the installation instructions (http://www.sdrsharp.com ).
 

There are some hardware things that I needed to do while waiting for the dongle. The dongle has a tiny MCX antenna plug. Fortunately Maplin sells an adaptor cable to standard TV socket (part N59LN) and I had already made a TV-BNC cable for another project, so this was not a problem. These dongles are very vulnerable to high levels of RF, so if you transmit while receiving on the dongle it will fry. The solution is to solder a couple of reversed diodes into the adaptor cable to limit the maximum input voltage.

The dongle arrived. The package also contained a remote control (only useful if you want to use the dongle for its intended purpose, but being radio amateurs we don’t do that do we?), a whip antenna (which works surprisingly well) and a software disk. Do not install this software as this will conflict with SDR#. The only tricky bit was changing the dongle driver from the Windows default to RTL 2832. To do this, you need a piece of software called Zadig (link on the SDR# site) and I also had to temporarily disable Heuristic protection in Norton which took violent exception to what I was trying to do.

All set, and Norton back to full protection, I plugged in the dongle and fired up the software. Operation was quite intuitive, but I started with the FM broadcast band – all was well and all the expected stations showed up on the display any gave me some strong, predictable signals to set up and learn how to use the software.

 

 

The dongle, with the E4000 tuner, covers from about 24MHz up to 1.7GHz, so it is a broadband device covering all the amateur bands from 12m up to 23cm. That’s the good news; the bad news is that there is no front-end filtering. Also these dongles mix the RF signal down to a few tens of kilohertz, to input to computer sound cards, so spurious signals are a real problem, particularly on the lower bands. For example I get a strong ‘Classic FM’ signal in the middle of the 10m band. It is possible to manage these phantom signals by carefully choosing the ‘Centre’ frequency and adjusting the RF gain, which can be accessed through the ‘Configuration’ menu, but my next move will be to build some filters to clean up the input signals.

I have also experimented with receiving  some digital modes using this SDR receiver. It is possible to patch the microphone socket to the speaker socket on most PCs so the digital modes can be decoded with standard software. There are a couple of drawbacks: you can’t hear the audio signal and the signal gets converted from digital to audio then back to digital again. There is a better solution – a piece of software called Virtual Audio Cable (  http://software.muzychenko.net/eng/vac.htm ), which does what the name suggests, but without the Digital/Audio conversions. With VAC, it is possible to ‘split’ the system so the audio output can be heard, recorded or shared with other programmes. I have successfully decoded RTTY, PSK-31 etc.

My Dongle SDR has several advantages: it is very small and everything is controlled from the keyboard so easy to configure. For example, filter bandwidth can be adjusted very precisely and easily.  The waterfall display, which can be adjusted, allows large segments of a band to be viewed at once and you can see when stations come and go then click on the ones you want to listen to. Combining the SDR with the VAC software provides a very flexible setup. For example, I can operate digi-modes while listening to my favourite music on the same computer. 

This SDR radio will never be as good as a full communications receiver, but it was definitely worth a tenner and I hope its performance will be even better with some front-end filtering. It has opened lots of opportunities for experimentation that were not available to me before and after this initial experiment, I may be tempted to invest in an SDR transceiver, but that is for another day.

10m (28 MHz) Activity

At long last the solar cycle has improved and the 10m (28 MHz) band has been 'open' during daylight hours recently.

Last weekend was the CQ World Wide (www.cqww.com) international amateur radio contest. This is a major event and as the weather was so bad over the weekend I was able to spend a bit of time operating. I decided to run just low power (5 Watts QRP, this is about the same power as a Christmas tree light!) and just one band - 10m. I was using my Yaesu FT-817 with a home-made vertical dipole in my loft. Conditons were quite good and I managed to work 116 other stations from the Middle East to USA East Coast.

Also on the 10m band, today I was able to pick up an amateur radio repeater, N2ACF/R, ( http://www.rra.net/ ) which is located in Rockland County north of New York City. This was carrying traffic for the amateur radio emergency net in preparation for the arrival of Tropical Storm Sandy, that is widely predicted to cause major damage in the New York area. I wish everyone in the path of the storm well and, while I hope the amateur radio support is not needed, I am pleased to see that the capability is available if needed.

Dave

6 Metre SMIRK Contest WInner

I am not a major amateur radio contester, but if I hear a contest in progress I will sometimes join in to give away a few points and to keep up my skill level. Occasionally, I will even submit a log.

So it was last June that I heard stations calling CQ Contest on 6m. A quick check of the contest database, which I have on my iPhone, gave me the rules for this SMIRK contest (http://www.smirk.org.) Conditions were good so I worked a few stations, sent my log off to the organisers and thought no more about it.

To my surprise, this week I received an envelope postmarked Pennsylvania and inside was a certificate confirming I had won first place in England! I checked the web site and sure enough, there I was. Unfortunately, I was the only station from England to submit a log which rather took the gloss off my achievement, but this is the only time I have ever come anywhere near the top of any contest so I don’t feel too bad about the lack of competition.

My 6m station is very modest – FT-817 running just 5 Watts and a home-made non-rotatable dipole, fabricated from some old  22mm copper pipe in the loft. But even with this, I can work all over Europe and occasionally beyond when there is a good E-opening.

So, it is worth entering contests even with a very modest score, and thanks to the SMIRK 6m club for running this event.

Dave M0BGR

Operating 2o12L and Mo0BGR

I got up early this morning to operate 2o12L (http://www.2o12L.com. Good session on 20m CW (Morse). Band condiitons were not great but lots of European stations and a few Asiatic Russians worked. I had hoped for some Far East stations, but conditions were not up to this. Unfortunately there were still lots calling when I had to close down to go to work (http://www.howardcommunications.ltd.uk) :-(



2o12L Antennas (some of them!).



Last night, I worked CW (Morse) on 30m from my own station Mo0BGR. Someone kindly 'spotted' me on the DX cluster so I got a nice run of stations. Nothing like a 2o12L pile up, as my station is slightly more modest, but it still kept me busy for a while.

Olympic Special Event Stations

I activated my own special event call, Mo0BGR with a short session on CW (Morse) last night. Conditions were not great, but the first station I worked was UX5MZ - thanks Igor.

Meanwhile over in Eltham, SE London not far from the Olympic venues, the Cray Valley special event 2o12L is going great guns, having worked over 5,000 contacts and 100 countries since Wednesday. For more details go to www.2o12l.com where you can find a list their working frequencies. 

If you are in London, before 9th September, then try to go along and visit 2o12L, how to get there is also on the web site and it is a really impressive station.

FM Switch Off - OFCOM Response

In August ast year I published a post on the governments plans to switch off FM radio in UK(http://m0bgr.blogspot.co.uk/2011/08/dab-radio-switching-off-fm-and-am.html ). At that time OFCOM was holding a 'consultation' and they have now responded to its findings. Their report is at http://stakeholders.ofcom.org.uk/binaries/consultations/dab-coverage-planning/statement/statement.pdf .

As predicted, OFCOM have swept aside all objections to the plan and asserted their previously held position that DAB is very wonderful so we don't need FM (subtext, the government have told us to sell the spectrum, just like they are now selling part of 143MHz - 156MHz band).

I have nothing against DAB radio, but I do not see it as a replacement for FM. It is technically inferior in many ways, particularly its coverage charateristics. DAB is based on obsolete technology and UK will have to adopt DAB+ or DRM at some point. DAB and FM do not use the same spectrum so, unlike the TV digital switch over, there is no need to close FM to allow expansion of DAB. Reading the consultation responses, the radio industry seems distinctly like warm about  switching to DAB.

If you use FM radio in UK, please let OFCOM know what you think.