Roamer.com » amateur radio

New digital voice mode requires just 1.1kHz bandwidth

theDoc — Wed, 05 Dec 2007 17:54:27 +0000

Jason Buchanan, N1SU, has announced a new digital voice mode based on WinDRM called FDMDV which claims to offer robust digital voice communication with enhanced interference rejection. The new mode requires just 1.1kHz of bandwidth and is claimed to work at signal to noise ratios as low as 3dB. It is based on 15 carriers using the 1400 MELP codec with no FEC. Fourteen 50 baud QPSK carriers with 75Hz spacing surround a central BPSK carrier at twice the power level for auto tuning and frame indication. Higher power in each carrier combined with an occupied 1.1kHz bandwidth provides improved robustness over its WinDRM and DRMDV predecessors. A poster on the WinDRM Google Group noted that audio quality was fair at an SNR lower than DRM versions.

Colossus Challenge

theDoc — Thu, 15 Nov 2007 18:01:01 +0000

To celebrate the rebuilding of the WWII code breaking machine Colossus, the National Museum of Computing is running a challenge. During 15th and 16th November, historic Lorenz SZ42 ciphertext will be transmitted by radio amateurs at Heinz Nixdorf MuseumForum in Paderborn, Germany at the following times and frequencies preceded by a preamble in RTTY. The preamble message, which contains information needed to receive the SZ42 transmission is here. The ciphertext will be received by two teams of amateur codebreakers at Bletchley Park. The first will comprise members of the Milton Keynes Amateur Radio Society operating amateur radio station callsign GB2BP and using modern equipment. The second team will use the same type of equipment as used in the intercept station in Knockholt in WWII. This equipment includes AR88 receivers with undulators connected for hardcopy output on strip tape. Tony Sale, who led the 14-year Colossus rebuild project, said it was not clear whether the wartime technology or a modern PC would be faster at cracking the codes. “A virtual Colossus written to run on a Pentium 2 laptop takes about the same time to break a cipher as Colossus does” he said. The Cipher Challenge is also being used to mark the start of a major fund-raising drive for the fledgling National Museum of Computing. The Museum will be based at Bletchley and Colossus will form the centrepiece of its exhibits. The Museum said it needed to raise about £6m to safeguard the future of the historic computers it has collected.

Oh when will I get my radio licence?

Roamer — Wed, 17 Oct 2007 20:43:53 +0000

This is the question I’ve been asking myself and others since Thursday when I passed my Foundation Amateur Radio exam.

The process is apparently as follows – On the night we took the exam the papers were marked and we got our results, then the papers were sent by post to the RSGB (The Radio Society of Great Britain), the RSGB then check and process the papers and tell OfCom (The body who looks after radio communications within the UK). OfCom then updates their systems and I should be able to then simply type my RSGB candidate number into the online lifetime licence system and hay presto! I should have a licence.

Now I do say should, but this system seems to not be working as well as expected, now some may say it’s simply down to the postal strikes, but I have read on a few sites around the place where people recently have passed on a saturday and got their licence and callsign by the following Tuesday – DURING the postal strikes – so whats happening now? I haven’t got a clue, but I recon that it’s just yet another thing that for no real reason is going wrong just for me LoL – either that or the RSGB are on a go-slow for exam candidates who aren’t also RSGB members (Membership currently is £44 – for what exactly?) – but that’s sounding too much like a conspiracy theory LoL.

Anyway, I will wait as patiently as I ever can, and keep trying the OfCom online system a couple of times a day until it works.