I am using Spectravue as SDR software because it gives me best performance for my goals.
I am using Spectravue for EME but also for tropo work and Airplane Scatter
Read my story using SDR for very weak signals by PA0EHG
The big advantage of Spectravue compared to other SDR software is that its simple in use and it has very good possibilities in showing extreme weak signals
I am using Spectravue version 3.15 in combination with a Funcube Dongle and a Funcube Dongle pro plus
I also tried other SDR software but in my opinion these have less possibilities in averaging or choosing very narrow Bandwidth.
This is a presentation of a signal with a signal to noise ratio of 4 dB in 12 Hz BW which is equivalent to -20 dB in 3 kHz
My settings for this are:
Using Combo display mode
FFT averaging : 5
FFT/BLK 8192 which gives a resolution Bandwidth of 12 Hz
Scale setting 1 dB/div, in this version is a bug and the display shows a scale of 2 dB/div
For signals even weaker or a carrier it's possible to increase the FFT Ave, sometimes I use 10 or 50
My standard setting for AS or EME is an FFT Ave of 5
When I am working EME and expecting very weak signals I reduce the span to 20 kHz
When working Aircraft Scatter I mostly use a span of 96 kHz
For solar noise or moon noise measurements, Spectravue has a feature other SDR software don't have.
It is the Continuum mode and with this it is very easy to make accurate measurements on noise levels.
As we all know accurate measurements can be easily corrupted by small mistakes
The most important in measuring moon and or solar noise is to be sure that the SDR receiver is operating well within the normal linear mode
The Funcube dongle is not very good in dealing with strong signals, leading it very fast into compression or generating spurious products
On the other side one needs to be sure that the noise of the pre-amp used is clearly visible on the Spectravue display.
When switching on and of the pre-amp I would like to have a least 20 dB or more rise off the noise floor shown on the Spectravue display.
Be careful however, when the IF feeding the Funcube with high gain in front that the bandwidth of that signal is not extremely wide.
When I connected a PLLLNB with 60 dB gain
and an IF running from 950 to 1950 MHz so 1000 MHz
If one is using a transverter between the Funcube and the Pre-amp for instance a DB6NT transverter from 10 GHz to 432 MHz it is not needed to use an extra attenuator. The IF bandwidth of the transverter is limited to several MHz and the total power level entering the Funcube will not get it into compression.
Set Spectravue in continuum mode for noise measurements
Be sure that the Funcube is well in its
Turning the antenna to a cold sky spot and then turning it to the moon or sun will give a rise of measured noise level.
On my 10 GHz EME equipment I measure:
With my 3 meter dish on 10 GHz I have 15 dB Solar noise or 2 dB moon noise
With my small setup a 50 cm dish I have 3.3 dB Solar noise and 0.1 dB moon noise
With my low cost setup with 64 cm offset dish I have 3.9 dB Solar noise and 0.2 dB moon noise
The moon noise measurements of 0.1 dB or 0.2 dB would not be possible using old noise meters
Example measuring Solar noise
The horizontal display is showing the noise power in time, you see the noise power rise because I am turning the antenna to the sun
Picture of solar noise with my 50 cm dish, look at the scale 0.5 dB/div
Example measuring moon noise
I started with the dish on the moon and at
10.04.03 i turned the dish away from the moon, The decrease off noise power
Picture of moon noise with my 50 cm dish, scale is at 0.1 dB/div
If needed one can increase the FFT Ave level, normally I use 5 or 10
If the difference is relatively small one can increase the