|
There has been an interesting discussion taking
place in the UK publication, "Medium Wave
News" and on their e-mail list.
I'm going to quote heavily from a discussion between
John
Faulkner (john.faulkner@xxxxxxxxxxxxx) and
Nick Hall Patch.
The basic premise is to take wideband SSB audio out of
any
analog receiver and fed it into the soundcard of your PC.
(Many
of us are doing this now for use with "Total
Recorder")
You then use the freeware "Dream" software, originally
developed
for DRM reception to act as a DSP filter for the audio.
The
results can be impressive. Haven't personally tried this of
yet, but
plan to do so in the next day or two.
If you're interested in downloading the software to try
this
technique, it is available at:
Below is an edited version of the discussion as it
appears
on the MWC E-Mail List:
=========================================
Quoting John Faulkner <john.faulkner@xxxxxxxxxxxxx>:
> > I conducted some tests yesterday evening at a friend's house (someone who is > very technically capable) and we devised a system of operation which would > give > the best results combined with ease of operation. Believe me, this software > will take some getting used to for some and I have found it a little > difficult > to grasp at times, though I am getting there. > > As I said in my earlier message, I first discovered this Sunday evening at > Julians where we were able to hear north American signals with reasonable > clarity during the early evening where his Lowe HF125 was, in many cases, > unable > to resolve the audio on its own. > > Dream will certainly enable some people to hear DX they otherwise wouldn't > hear > but this will depend on how selective their receiver is already - you might > notice little improvement with Dream, so I am currently trying to evaluate > if > Dream improves on the performance of my own setup. Initial tests have been > mixed though I probably didn't fully understand what I was doing. I have > just > conducted a particular test, however, which really was astonishing - I was > listening to the two stations on 6160 on my 7030 > http://www.john-faulkner.com/6160/6160%20via%207030.mp3 and with difficulty > due > to the splatter from the Austrian station on 6155. I was using the 2.1kHz > filter > of my 7030. Then I fed this into Dream, using 2, 3 and 5kHz IF filtering > and > this was the result ... > http://www.john-faulkner.com/6160/6160%20via%20Dream.mp3 > As you can hear, the results are very impressive - even compared to the > already > highly selective filtering of the 7030. I really think this is going to be > the > way forward for MW DXing but some will clearly benefit more than others. > You > will need to feed wideband SSB audio out of your receiver (10 - 15kHz > preferably) then into your PC or laptop sound card. > > On the 7030 I need to detune the received frequency by 7kHz in USB in order > to > render the signals visible in the Dream spectrum analyzer. Then you can > apply > all the necessary modes and filtering. Result - hopefully a much cleaner > signal > and less (or no) splatter. Quoting Nick Hall Patch Quite fascinating. It sounds like the IFDSP freeware, which was described in MW News awhile back, but IFDSP, (and, I think, the original intent of Dream) takes the IF from the receiver, not the audio, and after downconverting it to about 12 or 14 kHz in hardware, feeds the result to the sound card for DSP demodulation using the program. I'll have to see if I can make IFDSP work as you describe Dream working on the audio output of a detuned signal. |
_______________________________________________ IRCA mailing list IRCA@xxxxxxxxxxxxxxxx http://arizona.hard-core-dx.com/mailman/listinfo/irca Opinions expressed in messages on this mailing list are those of the original contributors and do not necessarily reflect the opinion of the IRCA, its editors, publishing staff, or officers For more information: http://www.ircaonline.org To Post a message: irca@xxxxxxxxxxxxxxxx