In a message dated 2/7/04 2:55:31 PM Eastern Standard Time,
btippett@alum.mit.edu writes:
>>"That means a receiver can handle signals from the noise floor to almost 40
dB over S9 without analog AGC.<<
That reminds me the "noise floor" thing in Orion. Disconnecting or shorting
the antenna terminals on Orion produced quite a bit of "noise floor." This
appears to be a noise generated by the circuits (IF amp after mixer?) Turning
the
preamp on, increases
the noise slightly, without moving Smeter.
This would explain or confirm K6SE's findings about the weak signal
reception, that weak signals can be masked by this internal noise and the few
rigs that
he tested and compared A/B performed better, or heard signals that Orion (and
Omni VI+) could not. DSP here doesn't help. Turning the preamp on should
help, providing that preamp has own internal noise lower than the rest of the
circuitry.
I tried some really weak signals on SSB and using NR DSP with different
settings didn't help, if anything it wiped it out. (AGC not participating here,
just weak signal on "quiet" band)
I will get K2 and see how does Orion fare in comparison under "K6SE test".
Yuri, K3BU.us
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