[R-390] Best approach for SSB mod on R-390A
Les Locklear
leslocklear at cableone.net
Sun Jan 3 21:03:10 EST 2010
Actually, the RX-350 sync detector is superior to the RX-340. Having had both side by side for a couple of months, I sold the RX-340. The 350 has good audio, better sync, better noise reduction, better notch filter. Too bad they decided not to keep selling them. The R8B sounded more mellow, but I prefer the 350 1 hz readout and the remote keypad tuning knob set-up.
Most people that own or owned the RX-350 don't understand the filter scheme or how to properly implement the synchronous detector.
It also sounds better than my NRD-545 and the dsp noise reduction is waaaaay better than the 545 which is not very good in that regard.
YMMV
Les Locklear
Hammarlund HQ-180A
Hammarlund SP-600 Re-Engineered by John R. Leary
JRC NRD-545
Ten Tec RX-350
----- Original Message -----
From: Cecil Acuff
To: r-390 at mailman.qth.net ; 2002tii
Sent: Sunday, January 03, 2010 7:45 PM
Subject: Re: [R-390] Best approach for SSB mod on R-390A
I think Ten-Tec uses a DSP implementation in the RX-340 and 350.
Les can report on both as he has owned each and still has one. Last I heard
it was good but still not up to the Drake R8B level..unless I
misunderstood...which happens more frequently these days.
Cecil
----- Original Message -----
From: "2002tii" <bmw2002tii at nerdshack.com>
To: <r-390 at mailman.qth.net>
Sent: Sunday, January 03, 2010 7:11 PM
Subject: Re: [R-390] Best approach for SSB mod on R-390A
> Andy wrote (regarding synchronous detection):
>
>>(2) The classy way to do it is put a computer and DSP in the loop where
>>the
>>oscillator is tuned with a D/A converter from the computer. The computer
>>and
>>DSP do digital spectral analysis and look at the signals all around, then
>>decide what number (frequency) to stuff into the D/A, and consequently
>>what
>>the oscillator frequency should be. This can be made arbitrarily smart,
>>although more often than not it is still pretty dumb. On some of the $$$
>>receivers, this "digital detector" is pretty good, like the high-end R&S
>>offerings these days. Not for the casual listener, of course. If you have
>>enough DSP horsepower, you do it all digitally with no hardware PLL at
>>all.
>>Being a DSP-head, this is my preferred implementation, but it takes a lot
>>of
>>careful DSP programming to make it work well.
>
> It's an intriguing notion, and I'd love to see a good DSP
> implementation. I have no doubt that Andy knows lots more about DSP
> than I do. Even with substantial DSP horsepower, I've never gotten
> decent results trying to implement synchronous detection in DSP, nor
> have I seen a decent commercial DSP implementation (though I have not
> seen an R&S DSP receiver).
>
> Best regards,
>
> Don
>
>
>
>
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