Hey all, Thanks for the help. Now I am able to receive all the packets to be "ok=true" because of the USRP's being kept near.. The commands that I have set from the /digital/narrowband folder are
Sender: ./benchmark_tx.py -p 4 -M 2 -f 2.435000061G --tx-gain=28 -r 250000 Receiver: ./benchmark_rx.py -p 4 -f 2.435000061G --rx-gain=53 -r 250000 I guess all this works because of the position of antenna placing it in a right way. But when I place them apart, for a farther distance, I have a packet loss of 150-200. I guess that's because of interference in the environment. Is there anything I can do to reduce those? Also, I wanted to do the same experiment by placing 2 more USRP and sending data to the receiver from different transmitter. Can anyone kindly help me with that issue?. Thanks. Please excuse me if I am not being informative. Regards, Dave On Fri, Sep 25, 2015 at 11:44 AM, Marcus Müller <marcus.muel...@ettus.com> wrote: > Hi Dave, > > obviously 95% success means a 5% packet error rate. That sounds pretty > physically sound -- for most constellations, you can calculate the symbol > error rate from the SNR, and from the symbol error rate it's a matter of > combinatorics to derive the lower boundary for packet error rate. > Again, this is wireless communication. It's not a "works perfectly/works > not at all" world, but a "works stochastically" world. 5% packet error rate > might or might not be acceptable, depending on a specific application. > > Best regards, > Marcus > > > On 09/25/2015 12:07 AM, Rama V wrote: > > Hi all, > I have tried to send packets to the receiver from /digital/narrowband > folder and it has mostly succeeded. The output I was able to get when I > sent the following commands were > > Sender: ./benchmark_tx.py -p 4 -M 2 -f 2.435000061G --tx-gain=28 -r 250000 > Receiver: ./benchmark_rx.py -p 4 -f 2.435000061G --rx-gain=54 -r 250000 > > ok = True pktno = 1323 n_rcvd = 1303 n_right = 1294 > ok = True pktno = 1324 n_rcvd = 1304 n_right = 1295 > ok = True pktno = 1325 n_rcvd = 1305 n_right = 1296 > ok = True pktno = 1326 n_rcvd = 1306 n_right = 1297 > ok = True pktno = 1327 n_rcvd = 1307 n_right = 1298 > ok = True pktno = 1328 n_rcvd = 1308 n_right = 1299 > ok = True pktno = 1329 n_rcvd = 1309 n_right = 1300 > ok = True pktno = 1330 n_rcvd = 1310 n_right = 1301 > ok = False pktno = 1331 n_rcvd = 1311 n_right = 1301 > > But there were a few packets where I have not received them correctly. I > guess only 95% of them were efficient in transmitting. I have tried > changing the gain settings and what I observed was that if I decrease the > gain from its normal value, the reception of packets are somewhat less > efficient. Can I kindly know what I might be able to do in order to receive > those packets in a more efficient way or is that what generally happens in > a real world transmission? Thanks > > Regards, > Dave > > On Tue, Sep 22, 2015 at 1:02 PM, Marcus Müller <marcus.muel...@ettus.com> > wrote: > >> Ok, >> >> This is because I have changed my folder to /digital/ofdm, I have started >> to receive packets. >> >> this means that you're using something *completely* different than >> before. It's simply a completely different transceiver system. >> >> kindly advise if I need to figure out the combination settings till most >> of them receive properly? >> >> Yes. You will need to figure out the optimum settings. Increase gain on >> the RX end, see if things get better or worse. Find an optimum for that. Do >> the same with the TX gain. >> >> Because even though I did not set any sample rate, the transmitter sent >> the information. >> >> As mentioned before multiple times: run the programs with "--help". They >> will show you what default settings they have. >> >> Please help. Please excuse me if I am being naive in asking these. >> >> It's alright to ask questions, but please remember to apply the things we >> tell you. >> >> Best regards, >> Marucs >> >> >> On 22.09.2015 00:59, Rama V wrote: >> >> Hi, >> As advised, the problem has been solved to a little extent where I have >> got the below results by giving the commands as >> >> Sender : ./benchmark_tx.py -f 2.435G --tx-gain=25 >> Receiver: ./benchmark_rx.py -f 2.435G --rx-gain 50 >> >> ok: True pktno: 1971 n_rcvd: 1687 n_right: 358 >> ok: False pktno: 1972 n_rcvd: 1688 n_right: 358 >> ok: False pktno: 1973 n_rcvd: 1689 n_right: 358 >> ok: False pktno: 1974 n_rcvd: 1690 n_right: 358 >> ok: True pktno: 1975 n_rcvd: 1691 n_right: 359 >> ok: False pktno: 1976 n_rcvd: 1692 n_right: 359 >> ok: True pktno: 1977 n_rcvd: 1693 n_right: 360 >> ok: False pktno: 1978 n_rcvd: 1694 n_right: 360 >> ok: True pktno: 1979 n_rcvd: 1695 n_right: 361 >> ok: True pktno: 1980 n_rcvd: 1696 n_right: 362 >> ok: False pktno: 1981 n_rcvd: 1697 n_right: 362 >> ok: True pktno: 1982 n_rcvd: 1698 n_right: 363 >> ok: False pktno: 1983 n_rcvd: 1699 n_right: 363 >> ok: True pktno: 1984 n_rcvd: 1700 n_right: 364 >> ok: False pktno: 1985 n_rcvd: 1701 n_right: 364 >> ok: True pktno: 1986 n_rcvd: 1702 n_right: 365 >> ok: False pktno: 1987 n_rcvd: 1703 n_right: 365 >> ok: True pktno: 1988 n_rcvd: 1704 n_right: 366 >> >> This is because I have changed my folder to /digital/ofdm, I have started >> to receive packets. But I guess this is only 50% efficient in receiving >> packets. Not all of them have been receiving properly. kindly advise if I >> need to figure out the combination settings till most of them receive >> properly? Because even though I did not set any sample rate, the >> transmitter sent the information. Please help. Please excuse me if I am >> being naive in asking these. >> >> Regards, >> Dave >> >> On Mon, Sep 21, 2015 at 11:00 AM, Rama V <ramav...@gmail.com> wrote: >> >>> Hi, >>> Thanks Marcus. I will do as you have advised and approach if any >>> uncertainties. >>> >>> Regards, >>> Dave >>> >>> On Mon, Sep 21, 2015 at 10:16 AM, Marcus Müller < >>> marcus.muel...@ettus.com> wrote: >>> >>>> Hi Dave, >>>> >>>> you shouldn't be modifying the python files before you understand what >>>> they do exactly. Please revert your edits, because it will be impossible to >>>> help you if you don't use the same scripts as we do, obviously. We've >>>> talked about this[1]. >>>> >>>> So: >>>> >>>> Sender : benchmark_tx.py -f 2.435G -r 250k >>>> Receiver : benchmark_rx.py -f 2.435G >>>> >>>> That's wrong! Now, your transmitter sends 250,000 bits per second, but >>>> your receiver expects 100.000 (the default value, which doesn't work with >>>> your hardware), so that's not good. Use the same setting for both >>>> benchmark_tx and benchmark_rx. >>>> >>>> So all you say is I need to change and play with the sampling rates and >>>> --tx-amplitude until the received packet becomes 'n_rcvd=1' >>>> >>>> No. RF is not "hey, there's this correct setting, let's apply it >>>> everywhere"; you'll have to figure out which combination settings work >>>> best. Generally, I'd leave the --tx-amplitude untouched, because 0.25 is a >>>> sane value for the digital samples; what you want is analog gain, not >>>> digital scaling. >>>> >>>> You should really set a TX gain and a RX gain. Try around with a few >>>> different gain settings for RX and TX gain -- a good approach would be to >>>> set something like 25 dB TX gain, and around 50 dB RX gain, if you place >>>> your TX and RX antennas far enough from each other. Notice that I'm >>>> assuming you're using antennas, and no direct connection! If you're using a >>>> direct cable between TX and RX, please use an attenuator, because you might >>>> otherwise damage your hardware. >>>> >>>> To find out how to change the gains, please read the output of >>>> benchmark_tx.py --help >>>> and of >>>> benchmark_rx.py --help >>>> >>>> >>>> Best regards, >>>> Marcus >>>> >>>> >>>> [1] >>>> http://lists.gnu.org/archive/html/discuss-gnuradio/2015-09/msg00124.html >>>> >>>> On 21.09.2015 16:48, Rama V wrote: >>>> >>>> I have tried the following commands in the terminal >>>> >>>> Sender : benchmark_tx.py -f 2.435G -r 250k >>>> Receiver : benchmark_rx.py -f 2.435G >>>> >>>> But the data packets are not being sent correctly. I have been >>>> receiving the packets as ok=false. I have tried modifying benchmark python >>>> scripts. Can I do the modification of those scripts or evrything needs to >>>> be given in the command line. Please excuse me as I am slightly unable to >>>> understand. Thanks >>>> >>>> Regards, >>>> Dave >>>> On Sep 18, 2015 2:21 PM, "Rama V" <ramav...@gmail.com> wrote: >>>> >>>>> Thanks for the reply Michael. I will look into that as you have >>>>> advised. So all you say is I need to change and play with the sampling >>>>> rates and --tx-amplitude until the received packet becomes 'n_rcvd=1' and >>>>> CRC check changes to 'ok=true' from the narrowband folder? >>>>> >>>>> Regards, >>>>> Dave >>>>> >>>>> On Fri, Sep 18, 2015 at 12:40 PM, Michael Dickens < >>>>> michael.dick...@ettus.com> wrote: >>>>> >>>>>> Hi Dave - I'm thinking that you are confusing "--samples-per-symbol" >>>>>> for the sample rate. I think the option you're looking for is "-r". Look >>>>>> at >>>>>> the "--help" for those examples when you get a chance. - MLD >>>>>> >>>>>> On Thu, Sep 17, 2015, at 02:01 PM, Rama V wrote: >>>>>> >>>>>> Thank you very much Michael. I will follow up on your advice. I am >>>>>> sorry that I wasn't able to understand some parts in GNU RADIO and didn't >>>>>> specify enough information. Regarding the question, I have been doing >>>>>> the >>>>>> benchmark in the digital/ narrowband/ folder. The exact commands I have >>>>>> been working on are >>>>>> >>>>>> Sender: benchmark_tx.py -f 2.435G --tx-gain 25 --samples-per-symbol >>>>>> 250000 >>>>>> >>>>>> Receiver: benchmark_rx.py -f 2.435G >>>>>> >>>>>> When I give 250kS/s, my laptop freezes. USRP is XCVR2450. So I >>>>>> started to give less Samples like 50kS/s so that they communicate with >>>>>> each >>>>>> other without errors. But I couldn't figure out the solution to that. So >>>>>> I >>>>>> just have a doubt whether I need to modify benchmark scripts or is it >>>>>> enough for the parameters I give in the command line. Thanks for the >>>>>> help. >>>>>> Please advice >>>>>> >>>>>> >>>>>> >>>>> >>>>> >>>> >>>> _______________________________________________ >>>> Discuss-gnuradio mailing >>>> listDiscuss-gnuradio@gnu.orghttps://lists.gnu.org/mailman/listinfo/discuss-gnuradio >>>> >>>> >>>> >>>> _______________________________________________ >>>> Discuss-gnuradio mailing list >>>> Discuss-gnuradio@gnu.org >>>> https://lists.gnu.org/mailman/listinfo/discuss-gnuradio >>>> >>>> >>> >> >> > >
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