Hello everybody
Im creating multi mudulation transmitter - project at my university. I have a conceptual problem.
I have analog modulations: AM, SSB, FM - narrow and wide
and digital modulations: qam, qpsk, gfsk
and I want to have largest bandwith as possible :) to transmit all modulations simultanously.
Scheme of my transmitter is:
/ AM \
wav source (16 KHz) - Matrix multiply - SSB - Matrix Multiply -> USRP Dev
- FM N -
- FM W -
- QAM -
- QPSK -
\ gfsk -
And now is my question :)
I have now Sample Rate for whole project and Device - 2Mega Samples
When I want to transmit all analog modulations with rate o 2 MS it is good
But when I want to add one of digital modulation to analog modulation, I get Underrun after 3 minutes.
But best is that when I run all digital modulation (no analog modulation) it behave properly.
I have put sample sate probes on all modulations and after WAV file and here can be interesting thing:
1) when analog is transmitted only output Sample Rate of WAV Source is 16 KHz, but when digital is send Sample Rate is 2.5 Mega samples
Is it proper to send analog and digital modulation in parallel ?? I I see this, there are two different sample rate here ?!
All The Best
Przemek