Re: [Discuss-gnuradio] tx_ofdm and rx_ofdm
Hi Martin: Thank you so much for your help.It can run.Thanks. Best regards xianda At 2014-05-26 20:40:08,"Martin Braun" wrote: >On 26.05.2014 13:03, xianda wrote: >> Hi: >> Now I run the example(tx_ofdm and rx_ofdm) through two usrps.(The >> version of my gnuradio is 3.7.4). >> 1.But in the receive part I receive two many things like this: >> INFO: Detected an invalid packet at item 139632 >> INFO: Parser returned #f > >Xianda, > >this questions pops up a lot on this list, and 99% of the time it means >your RF settings are distorting your signal. Try reducing gain and >multiplier, and make sure you get a nice spectrum before you try and >receive (i.e. check it with uhd_fft and make sure it's rectangular). > >> UHD Warning: >> The hardware does not support the requested TX sample rate: >> Target sample rate: 0.10 MSps >> Actual sample rate: 0.195312 MSps >> And the device I use is USRP N210.And I set the sample rate is 100k. >> Some days ago,someone tell me set the sample rate 100M/even number.And >> the 100k seems right,why this UHD warning?Can someone tell me what is >> the appropriate sample rate for USRP N210?Thank you very much. > >If you want 100K, you need to resample on the host. A stock N210 can go >down to 100e6/512 (i.e. what you're seeing). But that's OK, resampling >from 200k to 100k is not too CPU-intensive if you have a decent hardware. > >M > > >___ >Discuss-gnuradio mailing list >Discuss-gnuradio@gnu.org >https://lists.gnu.org/mailman/listinfo/discuss-gnuradio ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] tx_ofdm and rx_ofdm
Hi Jawad: Thank you so much for your help.Now it can run.Thanks. Best regards At 2014-05-26 20:44:13,"Jawad Seddar" wrote: First of all, I removed the OFDM receiver part from tx_ofdm and replaced it by a USRP sink and added a tag debugger to know when the data was generated from the transmitter. I also removed the OFDM transmitter part from rx_ofdm and replaced it by a USRP source. You can see all of this in the files attached. Change the frequencies and sample rates according to your needs. As long as there is data being sent and received, you shouldn't see any of the warning messages from the receiver. Regarding the sampling rate problem, I believe there is a minimal sample rate and you can't go below it. Regards, Jawad 2014-05-26 14:22 GMT+02:00 xianda : Hi Jawad: Thank you so much for your kindly reply. But the first problem still exist.Can you send me your test document and I test.Thank you. And the second problem is solved.Can you tell me why 200k is ok while 100k failed?(they are all 10M/(even number)).Thank you. Best regards, xianda At 2014-05-26 19:42:28,"Jawad Seddar" wrote: Hi xianda, I found out that using a factor of 0.05 in the multiply const works best for me, with USRPs about 50 - 100 cm appart and rx and tx gains set to 0. Try using a sample rate of 200k and you shouldn't get that sample rate error again. Regards, Jawad ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] tx_ofdm and rx_ofdm
On 26.05.2014 13:03, xianda wrote: Hi: Now I run the example(tx_ofdm and rx_ofdm) through two usrps.(The version of my gnuradio is 3.7.4). 1.But in the receive part I receive two many things like this: INFO: Detected an invalid packet at item 139632 INFO: Parser returned #f Xianda, this questions pops up a lot on this list, and 99% of the time it means your RF settings are distorting your signal. Try reducing gain and multiplier, and make sure you get a nice spectrum before you try and receive (i.e. check it with uhd_fft and make sure it's rectangular). UHD Warning: The hardware does not support the requested TX sample rate: Target sample rate: 0.10 MSps Actual sample rate: 0.195312 MSps And the device I use is USRP N210.And I set the sample rate is 100k. Some days ago,someone tell me set the sample rate 100M/even number.And the 100k seems right,why this UHD warning?Can someone tell me what is the appropriate sample rate for USRP N210?Thank you very much. If you want 100K, you need to resample on the host. A stock N210 can go down to 100e6/512 (i.e. what you're seeing). But that's OK, resampling from 200k to 100k is not too CPU-intensive if you have a decent hardware. M ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] tx_ofdm and rx_ofdm
Hi Jawad: Thank you so much for your kindly reply. But the first problem still exist.Can you send me your test document and I test.Thank you. And the second problem is solved.Can you tell me why 200k is ok while 100k failed?(they are all 10M/(even number)).Thank you. Best regards, xianda At 2014-05-26 19:42:28,"Jawad Seddar" wrote: Hi xianda, I found out that using a factor of 0.05 in the multiply const works best for me, with USRPs about 50 - 100 cm appart and rx and tx gains set to 0. Try using a sample rate of 200k and you shouldn't get that sample rate error again. Regards, Jawad ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] tx_ofdm and rx_ofdm
Hi xianda, I found out that using a factor of 0.05 in the multiply const works best for me, with USRPs about 50 - 100 cm appart and rx and tx gains set to 0. Try using a sample rate of 200k and you shouldn't get that sample rate error again. Regards, Jawad ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
[Discuss-gnuradio] tx_ofdm and rx_ofdm
Hi: Now I run the example(tx_ofdm and rx_ofdm) through two usrps.(The version of my gnuradio is 3.7.4). 1.But in the receive part I receive two many things like this: INFO: Detected an invalid packet at item 139632 INFO: Parser returned #f INFO: Detected an invalid packet at item 139680 INFO: Parser returned #f INFO: Detected an invalid packet at item 139728 INFO: Parser returned #f INFO: Detected an invalid packet at item 139776 INFO: Parser returned #f INFO: Detected an invalid packet at item 139824 INFO: Parser returned #f INFO: Detected an invalid packet at item 139872 INFO: Parser returned #f INFO: Detected an invalid packet at item 139920 INFO: Parser returned #f INFO: Detected an invalid packet at item 139968 INFO: Parser returned #f INFO: Detected an invalid packet at item 140016 INFO: Parser returned #f INFO: Detected an invalid packet at item 140064 And I search the maillist and I find someone encounter the same problem like me.(http://lists.gnu.org/archive/html/discuss-gnuradio/2013-11/msg00082.html)And I see"As long as the receive SNR is high enough, the problem does not show up."And I try to increase the "Multiply Const" to increase the snr.But it failed.And I try to increase the receive gain.And also failed.Can someone help me?Thank you very much. 2.And in the transmit part: UHD Warning: The hardware does not support the requested TX sample rate: Target sample rate: 0.10 MSps Actual sample rate: 0.195312 MSps And the device I use is USRP N210.And I set the sample rate is 100k. Some days ago,someone tell me set the sample rate 100M/even number.And the 100k seems right,why this UHD warning?Can someone tell me what is the appropriate sample rate for USRP N210?Thank you very much. Any advices will be appreciated.Thank you. Best regards xianda___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] tx_ofdm
On 05/23/2014 11:33 AM, xianda wrote: > Hi Martin: >Thank you for your reply. > But, > 1.I see the virual Source(Stream ID:Payload Bits)->Chunks > to Symbols(Symbol Table(-0.707...))(modulate:qpsk)?When I input 800 bits > to the Packet Header Generator,then chunks to symbols.How many symbols > generate in this way?When I input 800 bits to the Repack Bits,then > chunks to symbols.How many symbols generate in this way?Thank you very much. I'm pretty sure I've answered all of these questions already. > 2.I also see another ofdm in the old version of > gnuradio.And the module structure is attached.And the connect code in > python: Just ignore that. The new stuff is a complete rewrite. > 3.And i use two usrps to run the tx_ofdm.grc and > rx_ofdm.grc.The adjust code I also attached. But in the transmit,so many > U U U display.Why?And in the receive part,I also encouter problem.Can > you help me explain it? Your computer is too slow. M > Thank you very much.I see the ofdm part many days.And the > 3 questions I encounter.Thank you.Sorry for my poor English if you can't > understand.Thank you in advance.Thank you for your patience. > Best regards > > > > > > > At 2014-05-23 16:40:55,"Martin Braun" wrote: >>On 05/23/2014 02:29 AM, xianda wrote: >>> Hi: >>> Thank you so much. >>> 1.But from "chunks to symbols" I see you use the bpsk and qpsk >>> both.Right?What is the relationship between 800 bits and 17 >>> symbols?Namely,how to calculate the 17 symbols? >>> 17*64=1088.Can you explain? >> >>1 OFDM symbol @ BPSK == 48 bits in this configuration. >>ceil(800/48) == 17. >> >>> 2.I have looked at your ppt about the ofdm.You say now have two >>> version ofdm.Can you give me some links to them?Or some advices?Thank you. >> >>They're both in the tree. If you start working off of rx_ofdm an tx_ofdm >>you're already using the new stuff; no need to worry about this. >> >>M >> >> >>> Best regards >>> At 2014-05-23 04:33:44,"Martin Braun" wrote: On 05/22/2014 10:12 PM, eontool wrote: > IIRC, the tx and rx files are just a very general implementation of the > OFDM > model. > > Here's my understanding: > > - Packet length refers to the data necessary to produce n symbols (48 data > carriers, 2 symbols = 96). Er, no. This is the number of bytes per packet. It's 96 because we add 4 bytes for CRC, and then the packet number is a round value. At 100 bytes per packet, the payload is 800 bits. With BPSK, that would be 17 OFDM symbols (plus 1 OFDM symbol for header, and 2 for preamble). You can set whatever here, but remember that the stock equalizers don't do a good job on long packets. Also, the length can vary per packet. > - The number of total carriers in the systems equals the FFT length. > In this case, 48 data carriers and 4 pilots, 52 total and the rest are set > to 0. This is correct (compare 802.11a standard). M ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio >> >> >>___ >>Discuss-gnuradio mailing list >>Discuss-gnuradio@gnu.org >>https://lists.gnu.org/mailman/listinfo/discuss-gnuradio > > > ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] tx_ofdm
On 05/23/2014 02:29 AM, xianda wrote: > Hi: > Thank you so much. > 1.But from "chunks to symbols" I see you use the bpsk and qpsk > both.Right?What is the relationship between 800 bits and 17 > symbols?Namely,how to calculate the 17 symbols? > 17*64=1088.Can you explain? 1 OFDM symbol @ BPSK == 48 bits in this configuration. ceil(800/48) == 17. > 2.I have looked at your ppt about the ofdm.You say now have two version > ofdm.Can you give me some links to them?Or some advices?Thank you. They're both in the tree. If you start working off of rx_ofdm an tx_ofdm you're already using the new stuff; no need to worry about this. M > Best regards > At 2014-05-23 04:33:44,"Martin Braun" wrote: >> On 05/22/2014 10:12 PM, eontool wrote: >>> IIRC, the tx and rx files are just a very general implementation of the >>> OFDM >>> model. >>> >>> Here's my understanding: >>> >>> - Packet length refers to the data necessary to produce n symbols (48 data >>> carriers, 2 symbols = 96). >> >> Er, no. This is the number of bytes per packet. It's 96 because we add 4 >> bytes for CRC, and then the packet number is a round value. >> >> At 100 bytes per packet, the payload is 800 bits. With BPSK, that would >> be 17 OFDM symbols (plus 1 OFDM symbol for header, and 2 for preamble). >> >> You can set whatever here, but remember that the stock equalizers don't >> do a good job on long packets. Also, the length can vary per packet. >> >>> - The number of total carriers in the systems equals the FFT length. >>> In this case, 48 data carriers and 4 pilots, 52 total and the rest are set >>> to 0. >> >> This is correct (compare 802.11a standard). >> >> M >> >> >> ___ >> Discuss-gnuradio mailing list >> Discuss-gnuradio@gnu.org >> https://lists.gnu.org/mailman/listinfo/discuss-gnuradio ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] tx_ofdm
Hi: Thank you so much. 1.But from "chunks to symbols" I see you use the bpsk and qpsk both.Right?What is the relationship between 800 bits and 17 symbols?Namely,how to calculate the 17 symbols? 17*64=1088.Can you explain? 2.I have looked at your ppt about the ofdm.You say now have two version ofdm.Can you give me some links to them?Or some advices?Thank you. Best regards At 2014-05-23 04:33:44,"Martin Braun" wrote: >On 05/22/2014 10:12 PM, eontool wrote: >> IIRC, the tx and rx files are just a very general implementation of the OFDM >> model. >> >> Here's my understanding: >> >> - Packet length refers to the data necessary to produce n symbols (48 data >> carriers, 2 symbols = 96). > >Er, no. This is the number of bytes per packet. It's 96 because we add 4 >bytes for CRC, and then the packet number is a round value. > >At 100 bytes per packet, the payload is 800 bits. With BPSK, that would >be 17 OFDM symbols (plus 1 OFDM symbol for header, and 2 for preamble). > >You can set whatever here, but remember that the stock equalizers don't >do a good job on long packets. Also, the length can vary per packet. > >> - The number of total carriers in the systems equals the FFT length. >> In this case, 48 data carriers and 4 pilots, 52 total and the rest are set >> to 0. > >This is correct (compare 802.11a standard). > >M > > >___ >Discuss-gnuradio mailing list >Discuss-gnuradio@gnu.org >https://lists.gnu.org/mailman/listinfo/discuss-gnuradio ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] tx_ofdm
On 05/22/2014 10:12 PM, eontool wrote: > IIRC, the tx and rx files are just a very general implementation of the OFDM > model. > > Here's my understanding: > > - Packet length refers to the data necessary to produce n symbols (48 data > carriers, 2 symbols = 96). Er, no. This is the number of bytes per packet. It's 96 because we add 4 bytes for CRC, and then the packet number is a round value. At 100 bytes per packet, the payload is 800 bits. With BPSK, that would be 17 OFDM symbols (plus 1 OFDM symbol for header, and 2 for preamble). You can set whatever here, but remember that the stock equalizers don't do a good job on long packets. Also, the length can vary per packet. > - The number of total carriers in the systems equals the FFT length. > In this case, 48 data carriers and 4 pilots, 52 total and the rest are set > to 0. This is correct (compare 802.11a standard). M ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] tx_ofdm
IIRC, the tx and rx files are just a very general implementation of the OFDM model. Here's my understanding: - Packet length refers to the data necessary to produce n symbols (48 data carriers, 2 symbols = 96). - The number of total carriers in the systems equals the FFT length. In this case, 48 data carriers and 4 pilots, 52 total and the rest are set to 0. I hope im sure about this, if anyone is able to confirm this just to be precise. http://gnuradio.org/doc/doxygen/page_ofdm.html http://gnuradio.org/doc/doxygen/page_packet_data.html -- View this message in context: http://gnuradio.4.n7.nabble.com/tx-ofdm-tp48430p48432.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
[Discuss-gnuradio] tx_ofdm
Hi everyone: I have already understand most part of the tx_ofdm.grc.But the some digital i can't calculate accurately. 1.stream_to_tagged_stream: Packet length=96 bytes.? 2.And ofdm_carrier_allocator:FFT_length=64(but 48 occupied carrier+4 pilot carriers!=64)? Thank you in advance.Thank you. Best regards ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
