Re: [IRCA] Sync Detection Question

[Rick Kunath <k9ao@xxxxxxxxxxx>]

On Monday 16 January 2006 03:37 pm, Nick Hall-Patch wrote:

>
> Certainly, not nearly as effective as the selectable sideband sync of the
> ICF-2010.
>

I have to second this opinion on the 2010 sync detector. 

I don't have any Drake gear any more, but on the AOR (AR-5000+3, AR-7030 Plus) 
and JRC (NRD-545) gear I use these days I find much the same thing. The ECSS 
(synchronous) detection does little for DX audio enhancement. It does help a 
lot on stronger SW and MW stations, but for digging deep into the noise it 
isn't really very effective. I have no complaints on the synchronous 
detectors in any of the gear I own mind you, they seem to really hold on 
well, they just aren't as effective for real DX-type signals.

What seems to work better for me is simply using USB or LSB and varying the 
passband tuning to get the frequency response I want and then to roll off the 
opposite sideband interference. 

This is exalted-carrier reception. Synchronous detection takes this one step 
further by phase-locking the reinserted carrier to the received carrier. This 
may be the problem with DX conditions. Perhaps the circuit really can't get a 
complete lock on a signal that weak with other cariers in the passband. 
Whatever the cause, on my equipment here I find that ordinary exalted-carrier 
mode in USB or LSB is superior. Tuning is a bit more critical to avoid tonal 
distortion, but not overly so.

I feed a TimeWave 599zx audio DSP filter with these receivers and see another 
improvement most of the time using the TimeWave too. As for the JRC DSP, it 
isn't of any use most of the time.

Rick Kunath
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