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RE: DSP Noise Reduction on Receive -- REPLY--




Jon & John,
I have watched this discussion with interest. My Sat  system is composed
of an ICOM 910H with the DSP module and an outboard Clear speech DSP. My
experience is that the #106DSP within the Icom is very poor. It is
variable, in depth of action, but anything other than the lowest
settings (1-4) are in no way expectable to me. The unit introduces large
amounts of distortion, making it's use very annoying. I have not brought
up the distortion analyzer, but I would estimate in the 10-20% range.
The Clearspeach, on the other hand, is a WONDERFUL box. With it in the
path, I normally view S/N values of -25 to -30db (beacon = 100% or 0VU)
on my VU meter in the final audio stream. I think you will be very
pleased with the CS. One simple item on the ICOM 901 that is very
effective is reducing the RF gain of the 910 to a visual value of S6-7.
I also shift the IF pass band up slightly which also makes a very
notable improvement.
73
Gunther Meisse
W8GSM

-----Original Message-----
From: owner-AMSAT-BB@AMSAT.Org [mailto:owner-AMSAT-BB@AMSAT.Org] On
Behalf Of John Wilcox / NS1Z
Sent: Sunday, February 09, 2003 7:00 PM
To: Jon Ogden; amsat-bb@AMSAT.Org
Subject: Re: [amsat-bb] DSP Noise Reduction on Receive


----- Original Message -----
From: "Jon Ogden" <na9d-2@speakeasy.net>


> While I have an FT-847, I am not using it in receive (using an FT-817 
> instead for RX) so I cannot really compare the two DSPs.  Although I
believe
> the Timewave is far superior.

This has been my impression as well. I never felt the DSP in my old '847
worked 'just right' and so hardly ever used it. It did reduce the
background noise when I did play with it but, hardly seemed worth the
effort. Probably I didn't take adequate time to learn to set it up
correctly.

> I have ordered a ClearSpeech II base unit.  Hopefully it will be in 
> this week.  I plan on adding that in the audio chain and I will report

> on how
it
> helps too.  From what I remember from playing with it at Dayton last 
> year, it blows the Timewave's random noise reducer out of the water.

Now this I am really interested in. While there are a lot of good
reviews on eHam etc about the ClearSpeech, no one I know has tried one
yet and been able to compare it to units I am familiar with, such as the
FT-847.

This could be a real contribution to the list if you go give us some
quantitative analysis on the '847 alone, with its own internal DSP and
then with just the ClearSpeech. While my 847 has found a more loving
home I have not installed the DSP into my IC-910H yet and, if the
ClearSpeech proves to live up to the claims made for it, I don't want to
spend money without getting the maximum return on it.

You won't mind missing a couple of days work to do this testing so I
don't have to wait, will you? 8-)


John Wilcox
NS1Z
871 Route 120
Rumford, ME  04276
PH: 207-364-2246
FX: 207-369-9747
FN44rn

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