First the good news, I now have 3.125 and 4.167 M Symbols per sec
working for DVB-S. Those are used by the Columbus Ohio TV repeater.
I have also been working on designing a four output switch mode power
supply. I am trying to just use parts from my junk box so the design does
not use any specialist chips just a load of op-amps. The original idea was
that it would take a 13.8v input and supply 12v, 10v 5v and -12v. That has
now changed and the PSU will probably produce 18v for my old laptop,
6v for the SDR, 5v for the MPEG encoder and 12v for the PA. Whether
I will be brave enough to trust a load of expensive equipment with my
SMPSU build on Veroboard is another matter!
Now for the bad news.
I have added code for 8 MHz and 6 MHz DVB-T channels, sadly the
interpolation and decimation ratios means that the processor
load has gone up considerably, unless I can find a way of reducing this
I am stuck. This is all due to the USRP2 having a fixed sample rate and
any weird rates have to get to that rate through interpolation and decimation.
The 7 Mhz version of DVB-T works well but that does not need the high
ratios that the others do.
The person that was going to supply me with a PA for 3.4 GHz is no
longer able to find it so it looks like I may have to go back to plan B which
is to use some of the pHEMTs I have to design a suitable amplifier.