G4GUO May 15, 2018 at 3:00 pm
- This topic was modified 8 months ago by G4GUO.
Is there a way of displaying the MER (in dB) value as well as
the EVM value when doing modulation analysis using Spike?
If not could it be added in a later version of the software.
It should be a relatively easy thing to do.
AndrewModeratorAndrew May 15, 2018 at 3:33 pm
There is not currently a way to display this number. To clarify as well, MER(dB) == SNR(dB) ?
You can find an equation for the EVM(%) -> SNR(dB) conversion here.
I can look into adding this for a future release of Spike. I look forward to your response.
AndrewG4GUO May 16, 2018 at 12:57 am
I have been doing the calculations manually. I am
working on DVB and they seem to use MER rather than
EVM. I am only interested in QPSK and 8PSK as the
other constellations are not supported by Spike.
In my own receiver software I use
calculating the RMS error and signal vectors from the
samples. Example here http://g4guo.blogspot.co.uk/
I hope you are able to add it as it would help me.
– CharlesG4GUO June 9, 2018 at 2:31 pm
Andrew while I am on the subject of ‘would be nice if’.
Could you please consider adding user defined constellations like those described in the R&S appnote
DVB-S2 Constellation definition
– CharlesG4GUO November 13, 2018 at 9:31 am
Thanks for adding custom constellations. Would it be possible to remove the restriction of having constellations that are a power of 2? An option in DVB-S2 is to have preamble / pilot symbols that fall outside of the data constellation, so for example in the case of 32APSK I actually need 36 constellation points.
AndrewModeratorAndrew November 13, 2018 at 12:34 pm
Thanks for the feedback. I’ll look into this, or at least see if there is a quick way to add something to solve this. It may involve adding dummy or duplicate points. Unfortunately I can’t provide a timeline for this right now.
I appreciate the requests and feedback you have been giving us. I hope some of the added functionality has been of use to you.
AndrewG4GUO November 13, 2018 at 1:26 pm
Yes it is most helpful, when I make changes to my software
I use it for making sure I have not done something silly.
I have also used it with screen capture software to do
a couple of presentations.
The software I was using before could only cope with QPSK
so having the ability to analyse more complex signals is very helpful.
I have created a set of CSV files for DVB-S2, they are currently
missing the preamble definitions and I will be happy to make them available if anyone needs them.
Keep up the good work.
You must be logged in to reply to this topic.