GNURadio and USRP2
This project is a major masterproject which heads several smaller projects. It is my first occupation with Software Defined Radio and I am getting into this intersting field step by step.
Inhaltsverzeichnis
1 Scope
1.1 Get to know the USRP2 and get it running
- 2010-10-20 Today my USRP2 arrived. Brought to me by FedEx. Got to pay VAT but well, that's fine.
I decided to insert the LFRX receiver board first and only in order not to break the TX board for a undecent SWR. After a while I discovered that the tool
find_usrps
will identify the USRP2 when connected directly to the GBit port of my desktop computer. Well, it does. Obviously the USRP does react on network access. Now, the only thing it needs to do is to run. Therefore I tried out the tool
usrp2_fft.py
and it gave me a wonderful spectrum scope of short wave frequencies.
1.2 Receive the first signal
- 2010-10-20 The same tool as above was well suitable as a proof that my USRP2 was actually working. So I decided to tune my Kenwood TS-450S to a frequency in the 14 MHz band and keep transmitting with FM in order to generate a signal. Well, that was the result!
- 2010-10-21 Today I understood that I am missing two things to operate the WBX transceiver module: One coax cable for the TRX and the necessary firmware to drive it. Will need to get it from somewhere...
- 2010-10-22 I tried out a ssb receiver program. Worked mostly fine. The only downside is that it responded with a very strong delay. I still don't understand why.
1.3 Transmit the first signal
This experiment works exactly the other way round: I use the USRP2 as a transmitter and see if I can detect it with my Kenwood TS-450S shortwave receiver.
- 2010-11-04 Great. I can transmit. But I see that my dummy load is really closed. I didn't get any signal out.
Here are the parameters:
- Sample rate 200k
- Signal source at 1 KHz, amplitude at a minimum of 0.001 - to make sure that a bad SWR does no harm. BTW, this is a good counter check that you can really influence the output power!
- USRP2 sink: interpolation 500, frequency 14 MHz
Result: I hear a clear signal at 14.000 MHz, +/- 1 kHz
1.4 Transmit a AM signal
Amplitude Modulation is the simplemost signal that you can generate. Here it comes:
2 Links
- http://www.funwithelectronics.com/?id=11
- http://gnuradio.org/redmine/wiki/1/UsrpFAQIntroFPGA
- http://james.ahlstrom.name/
- GnuRadio - A fantastic introduction!
