[Date Prev][Date Next][Thread Prev][Thread Next] - [Date Index][Thread Index][Author Index]

Re: System NF Calculations

I imagine that the spec is actually 0.11uV for 10dB (S+N)/N (which
algebraically is S/N+1)
So -126dBm @ 10log(9)=9.54dB S/N
-135.54dBm @ 0dB S/N = FkTB (noise figure*Boltzman's
Take out the B (assume 2.5kHz) 10*log(2500)=34dB
kT at room temperature -174dBm/Hz

My FT-726R claims 0.15uV for 10dB (S+N)/N, which would be
20*log(.15/.11)=2.7dB worse (NF=7.84+2.7=10.54dB).

But, if you have sufficient gain in front of the RX, then NF(RX) isn't too
important.  One must work out the system noise figure calculation to
determine "sufficient".  

At 11:35 PM 5/18/01 -0400, Joe Leikhim wrote:
>What is a typical noise figure for a multi-mode radio?
>The 15dB in the spreadsheet example sounds like pretty sorry
>The ICOM radios are spec'd at about  0.11uv (-126 dBm) for 10dB S/N in
>CW/SSB modes. How does that equate to NF and  MDS?
>Joe Leikhim K4SAT
>"tv dinner by the pool,
>i'm so glad i finished school" -F.Zappa 1967
>"The Revolution will NOT be televised" -Gil Scott Heron
>"Whats he building in there?"- Tom Waits
>"The large print giveth
> and the small print taketh away..." Tom Waits.
>Via the amsat-bb mailing list at AMSAT.ORG courtesy of AMSAT-NA.
>To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org
Scott Townley		
Gilbert, AZ  DM43
HF/VHF/UHF/Satellite MOBILE station

"When the Going gets Weird, the Weird turn Pro"
Raoul Duke, Sportswriter

"Don't worry Boys, we'll weather this Storm of Approval and come out as
Hated as Ever"

Via the amsat-bb mailing list at AMSAT.ORG courtesy of AMSAT-NA.
To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org