[AMPS] radios/imd/intercept points

[Larry L. Ravlin]

Hi all,

All of this is a moot point, show me a rcvr better than a Collins R390A and
I will get it.

Larry L. Ravlin AKA (Laurence the Magnificent)
"Collins Equipt forever"
Ham Radio Operator K0AEY
Walterville, Or.
sheepdip@continet.com

"this is not a rice storage facility"
 

  






 




 
 




 

----------
> From: Peter Chadwick <Peter_Chadwick@mitel.com>
> To: 'igor rosky' <irosky@yahoo.com>; 'amps' <amps@contesting.com>
> Subject: RE: [AMPS] radios/imd/intercept points
> Date: Wednesday, June 02, 1999 9:43 AM
> 
> 
> Igor says:
> 
> >secondly the  receivers  3rd order intercept points
> 
> Unfortunately, this still fails to address the fact that a high intercept
> point in a receiver is totally useless without adequate phase noise
> performance to go with it. A +20dBm third order input intercept point
needs
> at least  -131dBc/Hz phase noise performance at the offset at which IMD
is
> measured.
> 
> For a 10dB noise figure and SSB bandwidth, the noise floor is -140dBm. To
> produce IMD signals at noise floor with a +20dBm TOIP, the inputs are at 
> -33dBm - that's about 5mV, which is a big signal - S9 + 40 on the 'usual'
S
> meter standard. In practice, noise at the antenna will be at least 10dB
> above this. 
> 
> Admittedly, the number of IMD products is n(n-1)+ 1/2(n-1)(n-2) for a
system
> in which the front end bandwidth is less than a half octave, where n is
the
> number of input signals intermodulating. This does suggest a somewhat
higher
> intercept point is required than would be established just from
> consideration of the highest level signals, while the phase noise
> contribution is n times the number of signals. However, signal power
> distributions show that there are relatively few big signals (which make
the
> most phase noise contribution), and more lower level signals which
porduce
> the IMD noise contribution. Thus there is justification for having the
IMD
> dynamic range equal to the phase nosie dynamic range. See my paper at RF
> Expo, 1986.
> 
> 73
> 
> Peter G3RZP
> 
> 
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