RHF wrote:
On May 6, 10:38 pm, Telamon

M... Sushi,
Should not the Two separate IF Filters of the same Band-Width : one
for the 1st IF and one for the 2nd IF create a Series RF Signal
Path resulting in a better combined Filtering Shape Factor then one
along; plus improve the Ultimate Rejection of the RF Signal Path.
Shape Factor : 2.0 & 2.0 = 1.4
Ultimate Rejection : 60 dB & 60 dB = 90 dB
SNIP

- That's some very interesting math you got going there.
-
- --
- Telamon
- Ventura, California

Telamon - Did I say it was "Math" ?

Shape Factor : 2.0 (1st IF) and 2.0 (2nd IF) comes out
to roughly 1.4 at the end of the IF Processing Stages
in the Signal Path.

OK so 60 dB was a bad number so make it 85 dB.

Ultimate Rejection : 85 dB (1st IF) and 85 dB (2nd IF)
comes out to roughly 127 dB at the end of the IF
Processing Stages in the Signal Path.

practically speaking - no math required ~ RHF
.



RHF,

As far as I know there is no general method that allows you to combine
shape factors for two filters into a number describing the net result.

I also know of no general method for combining rejection of two filters
to give a meaningful net number.

So, please tell us how you arrive at these numbers.