Hi everyone, I currently use GRC 3.7.9.1 and only its In-Tree-Modules. PC: Lenovo Laptop W530 CPU: Intel i7-3610QM with 8GB RAM OS: Ubuntu 16.04 64 bit
I tried to create some easy examples of different modems. My first goal is to modulate ASCII- or WAV-files, add some noise, demodulate the data stream and save or hear the expected result. Maybe I am wrong, but i expect an lossless connection in GRC if I directly connect an modulator to its appropriate demodulator - particularly when i use the default values. The issue is, even without added noise it's not possible to get an lossless connection in software. My Flow-Graph looks like this: Wav File Source --> Float to Char --> QAM Mod --> Throttle --> QAM Demod --> Pack K Bits --> Char to Float --> Audio Sink I use [Float to Char] to reduce data and get a byte-stream. Of course this loss of data isn't reconstructable. But the incoming signal at the [Audio Sink] sounds extreme noisy and clips massively. It is also a little bit random how bad it is - at one start i can hear what song it is, at the next start it's just noise. I think i can say that the Problem is the mod-demod part: --> QAM Mod --> Throttle --> QAM Demod --> Pack K Bits --> because this: Wav File Source --> Float to Char --> Char to Float --> Audio Sink works pretty well. I attached the GRC file with the different modems to this thread. Of course only one Mod-Demod string can be active at a time. The results are commented with [Notes] in the GRC file. I also tried every modulation with reduced data rate (usage of down- and upsampling). I would be deeply greatful if someone may explain me my fallacy or how it would just work - especially for the QAM modulation mentioned at the beginning. Regards, Markus different_MODEMs_audio_test.grc <http://gnuradio.4.n7.nabble.com/file/n61674/different_MODEMs_audio_test.grc> -- View this message in context: http://gnuradio.4.n7.nabble.com/simple-mod-demod-combinations-doesn-t-work-tp61674.html Sent from the GnuRadio mailing list archive at Nabble.com. _______________________________________________ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
