Dear Kyeong Su Shin *Thanks for your reply, I will try your suggestions and then I will inform you with the results.*
*Best regards* *Hamzeh elsayed* On Thu, Dec 12, 2019 at 7:28 AM Kyeong Su Shin <[email protected]> wrote: > Hello Hamzeh, > > Sorry, but I think we need more details about your configurations (maybe > flowgraphs, pictures of the hardware, captured data, etc) in order to > answer your questions properly. > > But here are a few generic answers to the question: > > 1. > It depends. There is no single answer. > > 2. > You can either implement a software-level automatic gain control (harder), > or do this experimentally. Try to choose the gain level that maximises the > SNR of the received signal. Plotting out the periodogram of the signals is > helpful (USRP Source -> QT Frequency Sink). > > Some USRP boards and daughterboards have hardware AGCs on them. This > includes USRP B series units, if I recall correctly. You can try enabling > that. This not not necessarily optimal, however. > > 3. > Yes, different SDR transceivers have different RF frontends and therefore > different gain stages. It is less application-dependent, but some > applications work well on non-linear conditions while others dont, so > applications matter, too. You should figure this out experimentally > (easier) or by actually going thorugh hardware schematics and software > source codes (harder). > > 4. > I don't know, there are insufficient information to tackle your problem. > Maybe your flowgraph has issues. Maybe the spectrum is too crowded. Maybe > you used wrong antennas (RP-SMA) or antenna ports. There are too many > possibilities. One thing that you should try is plotting the received data, > before actually putting them into the processing chain. You can try hooking > up a QT Frequency Sink to the USRP source on GNU Radio and see if the > periodogram makes sense (looks OFDM-ish). > > Regards, > Kyeong Su Shin > ------------------------------ > *보낸 사람:* hamzeh elsayed <[email protected]> 대신 Discuss-gnuradio > <[email protected]> > *보낸 날짜:* 2019년 12월 10일 화요일 오후 6:33 > *받는 사람:* [email protected] <[email protected]> > *제목:* gr-ieee802-11 with USRP N210 and B200mini problems > > Dear all, > > I installed the gr-ieee802-11 project and run the wifi_loopback.grc file > and the output is correct. Then I edited the file to transmit and receive > from socket using “socket PDU” block, also the output is correct. After > that, I tried to transmit and receive from USRP SDRs, the following are the > tested I done: > > > > 1- I transmit and receive from the same SDR “B200mini” with the same > configuration found in the wifi_transceiver.grc file. > > a. If the rx_gain and tx_gain are approximately 0.27 (normalized) > and encoding BPSK 1/2 , then the sent data are received for (95%) and the > constellation sink is approximately good. > > b. If the rx_gain and tx_gain are less than or greater than 0.27 > and encoding BPSK 1/2 , then any data id not received and the constellation > sink is very bad. > > c. If the encoding is anyone except BPSK ½ for example 16 QAM ½ > etc.. any data is not received for any value of gain. > > > > 2- I transmit and receive from the same SDR “N210” with the same > configuration found in the wifi_transceiver.grc file. Any data is not > received for any gain and encoding configurations. > > > > 3- I transmit from USRP N210 and received from B200mini also any > data is not received for any gain and encoding configurations. > > > > 4- I transmit from USRP B200mini and received N210 from B200mini > also any data is not received for any gain and encoding configurations. > > Tests were done by using the following: > > OS: Ubuntu 16.04 LTS > > Gnuradio: 3.7.11 > > First SDR: USRP N210 with CBX daughter board > > Second SDR: B200mini > > Frequency: 2.415Ghz > > Bandwidth: default (0) > > Therefore, > > 1- what are the best settings I have to select in order to transmit > and receive data correctly for all cases? > > 2- how to select the best gain for any SDR? > > 3- Is there any relation between the SDR type and gain and the > application? > > 4- In general, where is the problem or the mistake I am doing? > > > in advance, thanks for your time and help. > > > Best Regards, > > Hamzeh Elsayed > > >
