There's a lot of discussion going on at the moment on the US "LowFER" mailing list about the relative merits of slow CW versus BPSK (in this case relating to the COHERENT/AFRICA software by Bill de C
to use slow CW bands. When you say "machine" modes, are you meaning CW decoded by software or by the brain (be it aurally or visually) ? There is a profound difference... Actually, there probably isn
This is all-important. Extremely weak stations require considerable additional work by the 'computer between the ears' to decipher what is signal and what is noise on the screen - just like aural Mor
Harry Woodhouse G3MFW from St. Austell Cornwall wrote to me re. the following : He went to the Scilly Isles last month and dismantled the antenna loading coils of the Decca station there. Then, with
From VE2IQ It worked on first try. I will now optimize the filter coefficients and write a single program to go directly from digitized samples on disk at 7200 s/s to a .wav file time-compressed at 8
It's been my experience that Soundcards replaying .WAV files can usually cope with any sampling rate above 5513Hz, although the resultant frequency generated may not be very accurate. The speeded up
Walter et al :- Doesn't specifying a dipole as the radiator automatically take antenna aperture into account, and cancels out frequency from the equation ? So if you take just the spreading out of th
Ah - I'd taken the factor of 30 outside the square root then. Careless !! Andy 'JNT -- From: cesare tagliabue[SMTP:[email protected]] Reply To: [email protected] Sent: 2000-06-07 12:11 To: rs
The AD9850 DDS Board is now with the PCB manufacturers. I went there yesterday to check the solder mask, and had a fascinating trip round the factory looking at PCB manufacture and SMT component pick
Anybody have an idea how to build an power amplifier with single tube ? I have some GU81's. They needs about Ua=2000 V and Ia(max)=600mA. I calculated Pi match, but values of capacitors are to high..
Now that the 'mystery signal' of last week has been identified and decoded by a number of people, I'll be transmitting Low Speed Sequential Multi Tone Hellschreiber again this weekend on 137.6kHz, th
That should read [email protected] not .org as stated. Andy G4JNT If anyone would like these parameters varied let me know on the other EMail account .......... -- The Information contained in this E-Ma
Yesterday (Sunday) I was transmitting a low power slow Hellschreiber beacon signal all day. Signal width was 2.5Hz / Pixel rate 2s on 137.6kHz. Power to the antenna was 6 Watts with ERP around 0.6mW.
That was the idea of the low power transmission. It looks as if there may still be some work to be done on optimising the pixel duration against particular decoding software settings - Spectrogram do
The real question is, why was the quarter wave antenna worse, not why was the CFA so good. A 1/4 monopole can approach 100% efficiency and can be 3dB up on a dipole when erected properly - in which c
Can anyone identify the issue(s) of Wireless World where it first appeared. It would be interesting to extract them from the archives and read up on just what was published Andy G4JNT -- From: Peter
You will not be able to shrink files and make them audible without processing the .WAV file data considerably. Merely changing the sampling rate will do nothing to improve readability. The stages nec
Well, the way I do it is to use a mixed down frequency centred on zero and use low pass filtering to give bandpass when mixed back up for listening. As described the method would need some low pass f
No, the version of Spectrogram I use does not have the time delay function. Use Spectran instead. For this 2.5Hz mode Gram will not go narrow enough I suspect. even if you do get the delay right. And
There is also the issue of reduced skin depth and extra losses when using steel wire, or any other magnetic material for that matter. Skin depth reduces as the square root of relative permeability, w
