Isn't the s-meter noise the integration of all of the noise in the filter passband (or something like that)? In other words, as you narrow your filter, I'd expect you to see the s-meter reading approach the panadapter reading.
- Jeff, K6JCA -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Behalf Of Philip J Gentile Sent: Thursday, June 14, 2007 7:54 AM To: Doug McCormack; flexradio@flex-radio.biz Subject: Re: [Flexradio] Noise Floor S meter vs Panadapter i would terminate the antenna connection into a 50 ohm load to measure noise. phil AB2JL ----- Original Message ----- From: "Doug McCormack" <[EMAIL PROTECTED]> To: <flexradio@flex-radio.biz> Sent: Thursday, June 14, 2007 11:29 AM Subject: [Flexradio] Noise Floor S meter vs Panadapter >I recently build the Elecraft kit to provide a reference signal for > calibration of my SDR1000. With the 50 uV reference my S meter shows > -73 dBm (S 9.0). At 1 uV reference, the meter shows -107 dBm ( S > 3.3). These two numbers show the S meter is perfectly calibrated. > > When I remove the Elecraft unit and no antenna is connected, the meter > shows a noise floor of -117 dBm (S1.3). But the panadapter shows > -145 dB. I wonder why the panadapter does not agree with the S meter. > Maybe I am should ground the antenna connector when measuring noise > floor? When people ask me about the noise floor, do I say -117 or > -145? > > I have always suspected my 5 year-old Dell 1.8 Ghz has high internal > noise possibly on the PCI bus. Perhaps this Dell system noise is > getting into my M44 sound card. I hope to have a new dual-core Intel > computer later this week. > > 73, Doug VE3EFC > -------------- next part -------------- > An HTML attachment was scrubbed... > URL: > http://mail.flex-radio.biz/pipermail/flexradio_flex-radio.biz/attachments/20 070614/d3f5da98/attachment.html > _______________________________________________ > FlexRadio mailing list > FlexRadio@flex-radio.biz > http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz > Archive Link: http://www.mail-archive.com/flexradio%40flex-radio.biz/ > FlexRadio Knowledge Base: http://kb.flex-radio.com/ > FlexRadio Homepage: http://www.flex-radio.com/ > _______________________________________________ FlexRadio mailing list FlexRadio@flex-radio.biz http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz Archive Link: http://www.mail-archive.com/flexradio%40flex-radio.biz/ FlexRadio Knowledge Base: http://kb.flex-radio.com/ FlexRadio Homepage: http://www.flex-radio.com/ _______________________________________________ FlexRadio mailing list FlexRadio@flex-radio.biz http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz Archive Link: http://www.mail-archive.com/flexradio%40flex-radio.biz/ FlexRadio Knowledge Base: http://kb.flex-radio.com/ FlexRadio Homepage: http://www.flex-radio.com/
