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*Subject*: Re: [amsat-bb] System NF Calculations*From*: Scott Townley <nx7u@xxxxxxxx>*Date*: Sat, 19 May 2001 08:13:16 -0700*In-Reply-To*: <3B05E9E4.BE099297@nettally.com>

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 constant*temperature*bandwidth) Take out the B (assume 2.5kHz) 10*log(2500)=34dB -135.54-34=-166.14dBm/Hz=FkT kT at room temperature -174dBm/Hz F=-166.14-174=7.84dB 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 >performance. >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 >Jleikhim@nettally.com > >http://www.ibiblio.org/jimmy/mcguinn/9000e.ram > >"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 nx7u@arrl.net Gilbert, AZ DM43 HF/VHF/UHF/Satellite MOBILE station http://www.primenet.com/~nx7u ------------ "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

**Follow-Ups**:**Re: System NF Calculations***From:*Joe Leikhim

**R: System NF Calculations***From:*i8cvs

**Re: System NF Calculations***From:*Bill Hurlock

**References**:**System NF Calculations***From:*Joe Leikhim

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