[Flexradio] Silly question / Noise floor
Hello, In Powersdr, how is computed the values of the noise floor across the spectrum in spectrum, panafall modes ?. To be more specific, those values relate to which bandwitdh ?. Kind regards Jean-marc F1HDI ___ FlexRadio Systems Mailing List FlexRadio@flex-radio.biz http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz Archives: http://www.mail-archive.com/flexradio%40flex-radio.biz/ Knowledge Base: http://kc.flexradio.com/ Homepage: http://www.flexradio.com/
Re: [Flexradio] Silly question / Noise floor
On 6/28/2011 9:14 AM, F1HDI wrote: Hello, In Powersdr, how is computed the values of the noise floor across the spectrum in spectrum, panafall modes ?. To be more specific, those values relate to which bandwitdh ?. It's not a silly question at all, and I would also like to see the answer. It depends, of course, on the bin size from the FFT, which is dependent on the sample rate. It is not as simple as 1/96k, however. I suspect there is some normalization done, maybe scaling it to a 1Hz bin, but that is pure speculation on my part. For reference, on 20m with Pre2 selected on my F3K, my noise floor is a little over -140dBm with a good 50ohm terminator. It goes up by at least 15dB when switching to a real antenna, so the preamp is not needed. Just to clarify, we are NOT talking about the S meter reading, which depends on the Rx bandwidth. The baseline noise level for the panadaptor and waterfall are independent of the chosen bandwidth. So, can anyone tell us what effective bin size is being used? 73 Alf NU8I Scottsdale AZ DM43an ___ FlexRadio Systems Mailing List FlexRadio@flex-radio.biz http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz Archives: http://www.mail-archive.com/flexradio%40flex-radio.biz/ Knowledge Base: http://kc.flexradio.com/ Homepage: http://www.flexradio.com/
[Flexradio] FS: Flex 1500
Offering it here first: Flex 1500, purchased new March 2011. Just acquired a new Flex 3000. Original box + cables, software, and Quick Start Guide. $530 including Priority Mail shipping CONUS. Add $7 for insurance if desired. Prefer PayPal. Thanks 73- Joe Veras, K9OCO ___ FlexRadio Systems Mailing List FlexRadio@flex-radio.biz http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz Archives: http://www.mail-archive.com/flexradio%40flex-radio.biz/ Knowledge Base: http://kc.flexradio.com/ Homepage: http://www.flexradio.com/
[Flexradio] Test
test ___ FlexRadio Systems Mailing List FlexRadio@flex-radio.biz http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz Archives: http://www.mail-archive.com/flexradio%40flex-radio.biz/ Knowledge Base: http://kc.flexradio.com/ Homepage: http://www.flexradio.com/
Re: [Flexradio] Silly question / Noise floor
Hello Jean-Marc: Not a silly question at all. In fact, a great question. The panadaptor is fixed at 4096 bins. Each bin is essentially a receiver with bandwidth equal to the sample rate divided by 4096. Example: for a FLEX-1500, which has sample rate of 48,000 samples per second, the bin bandwidth is 48000/4096 = 11.7 Hz The noise level is lower on the panadaptor, because of the lower (bin) bandwidth. The difference in dB relative to the S-Meter window can be calculated as the log of the difference in bandwidths. Example: The difference in noise level seen on the S-Meter, receiving through a CW filter of 500 Hz, and the panadaptor on a FLEX-1500 would be: dB = 10*LOG(Bandwidth-of-Receiver / Bandwidth-of-Panadaptor-Bin) = 10 * LOG (500/11.7) = 16.3 dB So the panadaptor noise floor will appear to be 16 dB lower than the S Meter value with a 500 Hz filter selected. This only applies to noise. The level of a narrow signal (one that will fit entirely inside of your filter) is independent of the filter bandwidth, so the level shown is the true level and no correction difference applies. --- Graham / KE9H FlexRadio Systems == On Tue, Jun 28, 2011 at 11:14 AM, F1HDI f1...@orange.fr wrote: Hello, In Powersdr, how is computed the values of the noise floor across the spectrum in spectrum, panafall modes ?. To be more specific, those values relate to which bandwitdh ?. Kind regards Jean-marc F1HDI __**_ FlexRadio Systems Mailing List FlexRadio@flex-radio.biz http://mail.flex-radio.biz/**mailman/listinfo/flexradio_**flex-radio.bizhttp://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz Archives: http://www.mail-archive.com/**flexradio%40flex-radio.biz/http://www.mail-archive.com/flexradio%40flex-radio.biz/ Knowledge Base: http://kc.flexradio.com/ Homepage: http://www.flexradio.com/ ___ FlexRadio Systems Mailing List FlexRadio@flex-radio.biz http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz Archives: http://www.mail-archive.com/flexradio%40flex-radio.biz/ Knowledge Base: http://kc.flexradio.com/ Homepage: http://www.flexradio.com/
[Flexradio] 1500 Sold
The Flex 1500 has been sold. Thanks to all who inquired. 73- Joe, K9OCO ___ FlexRadio Systems Mailing List FlexRadio@flex-radio.biz http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz Archives: http://www.mail-archive.com/flexradio%40flex-radio.biz/ Knowledge Base: http://kc.flexradio.com/ Homepage: http://www.flexradio.com/
