Alberto has it exactly correct. The PowerSDR software takes a known signal value (say -70 dBm) and does calibrations that sets all levels. When you see a noise floor on the PowerSDR panel it is very accurate after you have calibrated. The meter reads the integrated noise power from the entire filter passband just as a regular radio would do. So except for narrow filters, these can differ.
Ciao! Bob N4HY Alberto I2PHD wrote: >Frank Eory wrote: > > > >>In powersdr , the noise floor is -150dBm >>with the radio off and -135dBm with it on. Sdradio gives me -100dB. >> >> >> > >Frank, > > the two readings are not directly comparable. The value reported >by SDRadio is the ratio between the signal and the full-scale value >of the sound card ADC. So if your sound card starts to saturate with >an input of 1V, then -100dB means 10uV > >PowerSDR on the other hand gives you the dBm (not dB) value after a >step of calibration. Not knowing the details of that software I >cannot be more precise, maybe Bob or some other guys knowledgeable >about the innards of PowerSDR can comment further. > >73 Alberto I2PHD > > > > -- Laziness is the number one inspiration for ingenuity. Guilty as charged! ------------------------ Yahoo! Groups Sponsor --------------------~--> Get fast access to your favorite Yahoo! Groups. Make Yahoo! your home page http://us.click.yahoo.com/dpRU5A/wUILAA/yQLSAA/ELTolB/TM --------------------------------------------------------------------~-> Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/soft_radio/ <*> To unsubscribe from this group, send an email to: [EMAIL PROTECTED] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
