Well, I think you guys are both right.
The DSP operates ahead of the audio stage, and thus can be called IF.
Of course, the frequency of 14 khz is certainly in the audio range.
And no - we could never afford DSP done at high RF frequencies.
73 de Gary, AA2IZ
----- Original Message -----
From: "Bill Tippett" <btippett@alum.mit.edu>
To: <tentec@contesting.com>
Sent: Monday, May 05, 2003 6:59 PM
Subject: [TenTec] Hello Orion Users
> N4PY wrote:
> >The Orion DSP filters are NOT audio DSP filters.
>
> I beg to differ Carl...from page 52 of the Orion manual:
>
> From A3, cable 11 brings the IF signal to
> the 9-MHz IF (A4), where the hardware
> noise blanker operates in a wideband
> environment. Cables 14A and 14B route
> the wideband IF signal through the
> Sweep Amplifier (A13) to A7 for use in
> ORION's band scope feature. Three
> standard and three optional crystal filters
> (normally selected by the BW control)
> define the tuned signal bandwidth ahead
> of DSP filtering. This stage provides
> enough amplification to maintain the
> receiver sensitivity despite unavoidable
> filter losses. The amplified and bandlimited
> signal feeds the IF Converter
> (A5) via cable 16.
>
> A5 provides conversion to the 2nd IF,
> amplification, filtering, and conversion to
> the 3rd IF for processing in the A7 Logic
> board. Cable 18 carries the 14 kHz third
> IF to the DSP in A7.
> After digital signal processing in A7, the
> recovered audio travels through the
> Motherboard to the headphone jack on
> A8 and to the EXT SPKR and AUX I/O
> jacks on A12. From A12 wire cable 36
> runs to the internal speaker.
>
> DSP is done at the 14 kHz 3rd IF which is clearly audio.
> Believe me, you could not afford DSP done at RF frequencies.
>
> 73, Bill W4ZV
>
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