Good afternoon, all...

Have any of you seen any magazine articles or web sites that discuss
adding IF DSP filtering to any off-the-shelf commercial radios?

I have an Icom IC-735 and Yaesu FT-1000 that could benefit from that
treatment (even though I gotta say the noise blanker in the IC-735 is
amazing for 25+ year old technology).

Conceptually it doesn't seem like it should be too difficult... tap in to
the IF stream somewhere, direct it out to an external DSP box (or perhaps
even a small internal DSP board if there is room... I think the 735 has
enough internal room for that) and then the output of the DSP board goes
back into the IF stream.

I have 30+ years' experience in software development, mostly real time
systems, but none at all in DSPs so I thought this might be a good DSP
project for me to learn on.

But, I'd like to read up on whatever results others might have had in
doing similar efforts.

Any thoughts on that would be appreciated...

Rick WA1RKT

= = = = =

Eric Poole
RKT Technologies, Inc.
Londonderry, NH, USA
Providing software development consulting and services
to government and industry since 1979.
On the Web: http://www.rkt-tech.com

"Rick (W-A-one-R-K-T)" wrote in message
news

Good afternoon, all...

Have any of you seen any magazine articles or web sites that discuss
adding IF DSP filtering to any off-the-shelf commercial radios?

I have an Icom IC-735 and Yaesu FT-1000 that could benefit from that
treatment (even though I gotta say the noise blanker in the IC-735 is
amazing for 25+ year old technology).

Conceptually it doesn't seem like it should be too difficult... tap in to
the IF stream somewhere, direct it out to an external DSP box (or perhaps
even a small internal DSP board if there is room... I think the 735 has
enough internal room for that) and then the output of the DSP board goes
back into the IF stream.

I have 30+ years' experience in software development, mostly real time
systems, but none at all in DSPs so I thought this might be a good DSP
project for me to learn on.

But, I'd like to read up on whatever results others might have had in
doing similar efforts.

Any thoughts on that would be appreciated...

Rick WA1RKT

= = = = =

Eric Poole
RKT Technologies, Inc.
Londonderry, NH, USA
Providing software development consulting and services
to government and industry since 1979.
On the Web: http://www.rkt-tech.com

Rick,
It really depends on what you want to do.
If you just want to add it for receiving it is not hard to add except
that the AGC in most receivers is not set up to limit the voltage applied
to the first analog to digital converter. This needs to be done badly.
Filtering, amplification, detection, and audio processing can be done
straightforwardly. However, you will have to add or subtract Hz from
or add them to your frequency display yourself! Further because of
the filters that come before your ADC, you probably will not have as
good a control over the phase of the pass band as you could with a
different design. Probably simplest to just buy a T-T Jupiter and
use its general coverage characteristics right after the first IF of your
rig.
Now if you also want to add the DSP to the transmitting part, it gets even
more
complicated.

Full integration achieves much, much more than an IF strip DSP add-on,
as my Orion 565 has shown me. Take a look at its architecture or the
Flexradio 1000/5000
or the Omni VII or the Elecraft K3 for examples of what you get. If you
want
to program, you might want to get a Flexradio SDR 1000 which has an open
source code version.
73,
Ed, N5EI