SDR# Why is SDR# noise floor value different to other SDR programs?

[thewraith2008]

When testing in SDR#, the noise floor value (assumed dBm) does not show the same value as compared to the values shown in HDSDR, SDR-Console and SDRUNO.
The same RTL-SDR dongle and antenna where used for all programs tested, with the exception of SDRUNO which used the SDRPlay RSP1A.

SDR#

HDSDR

SDR-Console

SDRUNO

Should be noted, even when the SDRPlay RSP1A is used in SDR#, it shows the same elevated noise floor value.

I have seen a video of an old SDR# (v0.0.0.0) showing values similar to HDSDR, SDR-Console and SDRUNO.

Does anyone know why it has changed from been similar to other SDR programs to been different?
Is this value something other the dBm?

 

[millam]

SDR# value in dBFS
HDSDR value in dB
SDRConsole value in dBm
Each shows up on the display.

Mil

 

[thewraith2008]

Thanks for reply.
I forgot about the units of measure been used on the overlay for the spectrum view in SDR#.

 

[thewraith2008]

While on the topic of units of measure.

Here is something I've noticed with the units of measure conversion in SDR-Console.
In SDR-Console the scale can be switched to show three units of measure. dBm, dBuV and S meter.
The S meter value does not match up with the values of dBm, dBuV. see GIF below @ UHF.

Is seems SDR-Console uses the conversion for S Meter(*) that suit frequencies under 30 MHz. (* when frequency is above 30 MHz)
When looking up references to dBm, dBuV and S meter conversion charts (see the web sites below) the S Meter value should be S8-S9 for the dBm/dBuV values shown (in GIF) and when frequencies are above 144 MHz (as mentioned in "IARU Region 1 Technical Recommendation R.1" see link below).

S meter conversion chart #1
S meter conversion chart #2

IARU Region 1 Technical Recommendation R.1 - "STANDARDISATION OF S-METER READINGS" (page 9)

 

[thewraith2008]

Just a follow up to the above post of mine about SDR-Console S Meter.

Seems the S-Meter is a newly add feature (August 24th, 2019) and it mentions here that:

3. On the bands above 144 MHz this available power shall be -93 dBm (which corresponds to S-9) (Note: not currently implemented),