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*Subject*: R: [amsat-bb] S units*From*: "i8cvs" <domenico.i8cvs@xxxxxx>*Date*: Tue, 7 Oct 2003 00:22:20 +0200

Brian and All, For 30 MHz and lower S 9 = -73 dBm available signal power at the receiver input For 144 MHz and above S 9 = -93 dBm of available signal power at the receiver input. To convert dBm to microvolt, recall that E= SQR (R x P ) where E is in volt R is resistance in ohm and P is power in watt. Example: Since -93 dBm is 5,011 x 10 E -13 watt, than -93 dBm is equivalent to 5 microvolt across a 50 ohm input termination. However, for a matched signal generator where the output impedance is equal to the RX input impedance i.e. Z=50+j0 ohm, the generator voltage must be twice the voltage across the receiver input because of the voltage dividing effect of the two series impedances in the network. For a matched 50 ohm source, therefore, an input signal of -93 dBm corresponding to S 9 at 144 MHz and up requires a generator voltage of 10 microvolt. Similarly, for 30 MHz and lower an input signal of -73 dBm corresponding to S 9 requires a generator voltage of 100 microvolt in a matched 50 ohm system. 73" de i8CVS Domenico ----- Original Message ----- From: Brian <groupes@smart-tech.dk> To: <amsat-bb@AMSAT.Org> Sent: Monday, October 06, 2003 5:02 PM Subject: Re: [amsat-bb] S units > > ----- Original Message ----- > From: "i8cvs" <domenico.i8cvs@tin.it> > To: "Gerald Horn" <ghorn666@earthlink.net>; "AMSAT-BB" <amsat-bb@AMSAT.Org> > Sent: Monday, October 06, 2003 3:45 PM > Subject: R: [amsat-bb] S units > > > > The S 9 reference level for frequency bands above 144 MHz is -93 dBm > > available signal power at the receiver input. > > What about below 144MHz? > > > 73" de > > > > i8CVS Domenico > > Regards > Brian OZ1SKY > > ---- > Sent via amsat-bb@amsat.org. Opinions expressed are those of the author. > Not an AMSAT member? Join now to support the amateur satellite program! > To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org > ---- Sent via amsat-bb@amsat.org. Opinions expressed are those of the author. Not an AMSAT member? Join now to support the amateur satellite program! To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org

**References**:**S units***From:*Gerald Horn

**R: S units***From:*i8cvs

**Re: S units***From:*Brian

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