On Jun 15, 12:06*am, "Guy Atkins" wrote:
Hi John,

I enjoyed reading your comments on your classy new IC-7700!

Speaking of ECSS tuning with 2 khz filters, I have often thought that the
SDR receivers I have owned sound very good in ECSS with narrower bandwidths.
For comparison, you might like to listen to two MP3 files (recorded during
the same song).

The first is ECSS (I chose LSB) tuning of my local 1360 khz station (Spanish
lang.) with exactly a 2.0 khz bandwidth chosen:

http://www.guyatkins.com/files/sdr/p..._2khz_ecss.mp3

The 2nd recording, to compare to a fuller fidelity, Synchronous-AM mode at a
wide 12 kHz filter setting, is he

http://www.guyatkins.com/files/sdr/p...hz-sync-am.mp3

I think you'll agree that the 2 kHz wide recording is perfectly acceptable
in fidelity for DXing and even program listening if required in a situation
where interfering signals are close in frequency. The shape factor of the
filtering in the Perseus SDR is nearly textbook perfect at 1 to 1.1
(conservatively). I know your IC-7700 is similarly excellent in shape
factor.

The 12 kHz recording is quite a bit "fuller" sounding, with more upper
midrange in the voice and treble in the trumpets. On the spectrum display
for 1360 kHz, the station shows a modulation envelope slightly over 20 kHz
wide, but I note extremely little improvement in treble when I tune it with
a filter bandwidth greater than 12 kHz.

Best DX,

Guy Atkins
Puyallup, WA USA
www.perseus-sdr.blogspot.com

Hi Guy,
Certainly very impressive recordings from your Perseus = nice! I
read John Bryant's review of your Perseus next to his WinRadio 313 and
he is also most impressed with the Perseus (see Guy's Perseus
blogspot)

I think the reason my 7700 does better on ECSS with a tight filter is
because it has a later more developed DSP and also maybe the passband
offset works better as well. To get the optimum sound quality on an AM
station in ECSS it is necessary to shift the passband offset - in my
case it is optimal at minus -250 Hz setting. My 756Pro3, good as it
is, cannot match the 7700 with the 2 kHz filter.

JP