Hi Ray and John
The figures quoted on the Filter-Modulator test sheet are measured with a Serit Tuner and MiniTioune V0.6d software. If you are to make any comparisons between your set-up and the test sheet parameters, you need to use the V0.6d software version as Jean-Pierre has changed the MER calibration in V0.7b.
John: Having thought about this and compared your results with Ray's results, I think that everything is working as expected for you. Looks good!
The power measurements in MiniTioune V0.6d had an error of around 6 dB per octave of selected symbol rate as reported here
http://batc.org.uk/forum/viewtopic.php? ... 995#p11995. I'm really grateful to Jean-Pierre for resolving this in MiniTioune V.07b.
The filters on the Portsdown Filter-Modulator board are set a little too tight compared with the DVB-S standard and this shows up as a lower indicated clean-signal MER on the Serit Tuners. The problem is not apparent with the older Sharp tuners - and this is why it was not picked up at the design stage. However, I have since conducted tests under simulated weak-signal conditions (using attenuators and injected noise) , and have been unable to consistently measure any improvement in the resolvable signal strength using a wider, corrected, filter bandwidth. So, in short, the only effect seems to be a lower number in the box on the MiniTioune software.
Dave