One of the other comments I also found interesting was
that the "digital sections of the two receivers" are
identical. Essentially this will mean that whatever
performance differences there are between the two RX's
is solely determined by the analog circuitry preceding
it. Which simply underscores the reality that DSP IF's
are only ever as good as the analog stages ahead of
them. While DSP is a great thing, it can't however
perform magic and make up for poor/marginal analog RF
design practices.
I also found the decision to mirror the
Pegasus/Jupiter/RX350 IF frequency scheme for the sub
RX intriguing. Could the Orion sub RX design effort be
the precursor to a Pegasus II, Jupiter II, RX321, and
RX351 somewhere down the road? I for one hope so.
Duane
N9DG
...engines now cooled...
--- Jim Reid <jimr.reid@verizon.net> wrote:
> Hi,
>
> Yesterday, N9DG wrote, in part:
>
> "I was then immediately thrown into a conundrum
> pondering that
> the lowly 14Khz "audio" IF as being capable of "RF"
> speech
> processing, .... I'm sooooo confoozed."
>
> Well, audio frequency energy travels via air
> compression/
> rarifications. IF frequency energy travels via
> electromagnetic
> waves/currents which can be rf processed, digitally
> processed, etc.
> Don't confuse audio and rf energies, hi.
>
> There is no particular advantage to going to higher
> IFDSP frequencies,
> unless you could go all the way to 100 kHz or
> higher. Unfortunately,
> there are no available A/D:DSP components operating
> up there;
> that is, no 24 bit, 100+kHz A/D nor 32 bit SHARC
> DSP chips
> at 100+kHz, at least that I am aware about. Advise
> if such
> chips are, in fact, on the market and for what
> price, hi.
>
> Well, there is a chip set that operates even
> higher, but the
> chips alone are priced in the $2000 area! A bit
> high even for
> a high end amateur rig. BTW, the Icom 756ProII
> uses a 36kHz
> IF A/D+DSP chip set; however, II's performance
> specs do
> not reach that claimed for the Orion (103 dB IMD
> even down to
> a 3 or 4 kHz signal pair spacing) with +25 dBm IP3
> and +78 dBm
> for IP2.
>
> Note that the Ten Tec RX-340 rcvr has a spec of +30
> dBm for IP3,
> typical, and +25dBm minimum (but only +75 dBm IP2).
> The final
> IF to DSP frequency in the 340 is at 16 2/3 kHz.
>
> 73, Jim KH7M
>
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