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G0FTD > DSP 14.01.06 04:54l 86 Lines 2826 Bytes #999 (0) @ WW
BID : A43296G0FTD
Read: GUEST DK5RAS
Subj: RF vs DSP (some basic tests)
Path: DB0FHN<DB0MRW<DB0WUE<DK0WUE<7M3TJZ<ZL2BAU<GB7ESX<GB7NNA
Sent: 060113/2058z @:GB7NNA.#31.GBR.EU #:77221 $:A43296G0FTD [Witham, Esx]NNA
With the arrival of the Iom IC7000 on the market I've recently began
to consider getting one.
I decided to do some RF vs DSP tests here in the shack.
The RF side was:
IC706 MK2g with 500Hz narrow CW filter
The DSP side was:
The shack PC running software DSP (MultiPSK)
The test signal was a 2m beacon attenuated to be an extremely low signal.
I sid some comparisons and yes the various software options such as
60Hz bandpass and/or noise reduction were fantastic at producing
signal output purity.
I was also surprised at how I could copy the signal with careful
adjustment
of the traditional IF shift and narrow IF/RF filter.
OK there was considerably more noise present but I found that with the
nature of CW the noise wasn't much of a problem. The combination of
grey matter and CW in it's own right really do prove how effective the
mode is !
I have decided that careful use of DSP can enhance the received signal
so DSP does work but - there's a but ;-)
It was only showing it's edge when I *knew* there was a signal to be
resolved and could easily see the signal on an effective spectrum
scope.
Now the average operator tuning over the band would be receiving
signals at random and as such would probably miss any weak signals
and the oppurtunity to use DSP would be missed anyway - thus negating
having the DSP in the first place.
Of course if a QSO was already in progress and fades or QRM appears then
I agree that the DSP would be in a class of it's own.
So there's two sides to the story I suppose.
Would I get an IC-7000 though ?
Well - I think Icom have missed the oppurtunity to provide a rig
that warrants an immediate upgrade.
It's going to need a lot more goodies to become a must have upgrade.
The boast of a TV receiver is in reality a bit of a waste of time.
It only covers band 1 VHF, is not operative on all models and the
rig could at least be easily made to receive up to 1GHz for peanuts.
And Icom haven't even had the courtesy to include RJ454 protection
like Yaesu does. A small sleeve over the RJ45 stops the spring clip
from breakage, and in a portable/mobile environment where the breakage
is likely to occur then this is a black mark for Icom.
Icom's workshop refuse to assist customers with broken RJ45 clips, but
will happilly sell you a new microphone. No doubt the ic7000's dtmf
keypad mic will cost a bit more than a "normal" microphone.
The rtty decode - well so what..
What about PSK31 or packet ?
Or even SSTV decode which would have made the boast of using the screen
as a tv display somewhat more valid.
And by now I would have though simply plugging in a keyboard would
give users tx capability on rtty/psk31.
I'm an Icom fan - but in this case I don't think they've made enough
effort to win my cash.
I'll stick to my collection of 706's.
- Andy -
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