[Discuss-gnuradio] How to swtich tx/rx of XCVR2450 when using gnuradio OFDM_benchmark example?
HI guys, Thanks in advance. Currently I have been engaged in a project which is based on the OFDM_benchmark example. I plan to realize a round trip communication between two USRP2 node. Concretely, I want to control the node A switch to RX mode after it finishes transmitting a packet. In such way, the node A can receive the ACK from the node B. * I know XCVR2450 does not support FULL DUPLEX. BTW, I wonder if XCVR2450 can handle the tx/rx switch job automatically? Or should I implement some script (Python) to control it? * Any help or instruction will be greatly appreciated. Best, Kay. ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
[Discuss-gnuradio] Any way to sample/log the 50Mhz ISM signal in gnuradio with USRP2?
Hi guy, Thanks in advance. Currently I am implementing a project based on ofdm_bentchmark example with USRP2. I remember that the sample rate of ADC of USRP 2 with RF2450 can be up to 100MS/s. That means we can use USRP2 to capture at most 50Mhz bandwidth signal. Initially, I plan to log the signal on my computer (*save as dat. format)* and analyze it offline. Everything is fine when the sample rate(bandwidth) is set to 20MS/s in terminal. However, when we set the sample rate up to 50MS/s, nothing can be log in my computer. I guess there some software limitations in Gnuradio. My question is how to remove such limitation to achieve the 50MS/s sample rate. Any help will be greatly appreciated. Best, Kay ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
[Discuss-gnuradio] How can we adjust the ADC rate in usrp2 in ofdm benchmark example?
Hi guy, Thanks in advance. I am a new comer to gnuradio. Now I am handling the project based on ofdm benchmark. I want to down-sample ADC to 2M/s(default is 100M/s) to capture the low frequency signal, 1Mhz in our case. I guess the USRP capture all the signal using the maximal ADC rate by default. Does anyone know how to do that? Any help will be greatly appreciated. Best, Kay ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
[Discuss-gnuradio] Why the Qam modulation cannot work well in ofdm benchmark example?
Hi guys, Recently, I have conducted a project based on ofdm benchmark. However, when I use the high modulation rate like qam16 and qam64, the packet error rate increase significantly. I guess the reason is that the preamble in gunradio is too weak to do channel estimation, thereby raising the packet error rate. Furthermore, even though I test the example offline without going through the channel, the packet error rate still very high, which make me feel confused. It is supposed to perform normally offline, without any decoding error right? Best, Kay ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] why the code in gnuradio in 3.6 cannot work in 3.7?
Thanks for your reply, Martin. I have read the website about the change before. But still nothing change when I run benchmark example in terminal, even though I delete some original code in C++ block(for test). That means my added code cannot take effect. Do I miss something? Best, Kay 2013/10/11 Martin Braun (CEL) martin.br...@kit.edu Read http://gnuradio.org/redmine/projects/gnuradio/wiki/Move_3-6_to_3-7 MB On Fri, Oct 11, 2013 at 09:25:53PM +0800, Yingjie Chen wrote: Hi guy, I have updated the gunradio to 3.7.1, but fond the c++ block name and style changed a litter bit. like ofdm_insert_preamble.cc is changed to ofdm_instert_preamble_impl.cc. When I add some codes in general work funciton, and use the command make and make install it in build directory as usual in gnuradio 3.6, I cannot see any change after adding my personal code. I guess the build fire is not installed. what is happening in 3.7? Any help would be appreciated. Best, Kay ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio -- Karlsruhe Institute of Technology (KIT) Communications Engineering Lab (CEL) Dipl.-Ing. Martin Braun Research Associate Kaiserstraße 12 Building 05.01 76131 Karlsruhe Phone: +49 721 608-43790 Fax: +49 721 608-46071 www.cel.kit.edu KIT -- University of the State of Baden-Württemberg and National Laboratory of the Helmholtz Association ___ 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] How to estimate SNR in ofdm benchmark example?
Hi guy, Thanks in advance. I am currently doing a project in ofdm benchmark example. If I want to estimate the SNR in receiver side using USRP2, dose anyone know which block should I use and how should I connect it? Appreciate your great help. Best, Kay ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
[Discuss-gnuradio] Do anyone know how to add pilot to sub-carrier in benchmark ofdm example??
Hi guys, Thanks in advance. I am currently using Gnuradio 3.6. I want to use pilot to trace the phase offset in each ofdm symbol. However, I cannot see any pilot is added in ofdm benchmark example. Is there any example or project that has already implemented pilot to trace phase offset? If no, which block should I locate to do the least modification. Appreciate your great help. Best, Kay ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] Do anyone know how to add pilot to sub-carrier in benchmark ofdm example??
Thanks for you reply, Martin. But seem some blocks in GRC example is not compatible with the blocks in original benchmark ofdm example, I am supposed that I need major modification if I use it. 2013/8/27 Martin Braun (CEL) martin.br...@kit.edu On Tue, Aug 27, 2013 at 07:04:21PM +0800, Yingjie Chen wrote: Thanks in advance. I am currently using Gnuradio 3.6. I want to use pilot to trace the phase offset in each ofdm symbol. However, I cannot see any pilot is added in ofdm benchmark example. Is there any example or project that has already implemented pilot to trace phase offset? If no, which block should I locate to do the least modification. There is a detailed explanation in the manual. http://gnuradio.org/doc/doxygen/page_ofdm.html MB -- Karlsruhe Institute of Technology (KIT) Communications Engineering Lab (CEL) Dipl.-Ing. Martin Braun Research Associate Kaiserstraße 12 Building 05.01 76131 Karlsruhe Phone: +49 721 608-43790 Fax: +49 721 608-46071 www.cel.kit.edu KIT -- University of the State of Baden-Württemberg and National Laboratory of the Helmholtz Association ___ 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] How to add pilot in ofdm symbol in Gnuradio?
Dear all, Thanks in advance. I am currently using Gnuradio 3.6. I cannot see any pilot sub-carrier is used in ofdm benchmark example. I want to use pilot to trace the phase offset in each symbol. Is there any example or project that has already implemented pilot both in sender an receiver? Appreciate your great help. Best, Kay ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
[Discuss-gnuradio] something wrong after I add a new c++ block in gnuradio. ('module' object has no attribute)
Hi guys, Thanks in advance. I have add a new c++ block in gnuradio/gnuradio-core/src/lib/general, named *gr_multiply_const_cc1.cc*, with other two files, named * gr_multiply_const_cc1.h* and* gr_multiply_const_cc1.i. *I have add it in the Cmakelist and successfully pass the building process. After that, I import this block in python and manage to use it. (After make install). However, I got* a wrong message 'module' object has no attribute 'multiply_const_cc1' *in the terminal. Did I miss something? Could anyone help me, please. Best, Kay. ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
[Discuss-gnuradio] Can we trace the location of DC of each subcarrier in ofdm example?
Hi, guys Thanks in advance. I want to trace the residual freq. offset between sender and receiver after freq. offset correction by preamble. Hence, i need to know the exact location of Dc for each subcarrier? Is that possible to trace that? Best, Kay Sent from my iPhone ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
[Discuss-gnuradio] How can I add freq. offset(related to time index) after IFFT in data symbol in ofdm example?
Hi guys, Thanks in advance. Since freq. offset is time related, like exp(2pi * fΔ * t), how can I generate freq. offset in gnuradio? Normally, freq. offset exists due to mismatched oscillators between transmitter and receiver. Is that possible get the same freq. offset effect mentioned above, merely through modifying some code in GunRadio but not modifying the RF hardware in USRP. For example, if I want to add 1KHZ offset in sender in data symbol(not preamble part,to avoid freq. offset correction), to see if the receiver can still succeed to decode the data, how should I do? Which part should I locate at after IFFT moving the samples to base band? Thanks again. Best, Kay ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
[Discuss-gnuradio] Can I add frequency offset at sender in ofdm example
Hi, guys Thanks in advance. I plan to do a experiment in usrp that intentionally adding some frequency offset in data symbol before transmission. Is that feasible to implement it in gnuradio? Which block should I modify at sender side? Sent from my iPhone ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
[Discuss-gnuradio] Why other correlators(ml or pnac) can not work in ofdm example except for Schmidl and Cox correlator(default)?
HI guy, I have checked the code in ofdm_receiver.py and found that gnuradio uses Schmidl and Cox as default correlator for frame detection. However, when I change to other correlators like* ml or pnac*,the receiver cannot receiver any more. Is there any problem with that? Thanks so much. Best, Kay ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] Why other correlators(ml or pnac) can not work in ofdm example except for Schmidl and Cox correlator(default)?
Thanks for you reply. Can you tell me what should I do next? Update the code or other things? Cause I am very urgent with my project and need to use other correlator(like pnac). Thanks in advance. 2013/5/2 Martin Braun (CEL) martin.br...@kit.edu On Thu, May 02, 2013 at 04:52:53PM +0800, Yingjie Chen wrote: I have checked the code in ofdm_receiver.py and found that gnuradio uses Schmidl and Cox as default correlator for frame detection. However, when I change to other correlators like ml or pnac,the receiver cannot receiver any more. Is there any problem with that? Thanks so much. The OFDM code is under heavy maintenance right now. The code you're inspecting is a bit outdated and it's quite likely it doesn't work properly. MB -- Karlsruhe Institute of Technology (KIT) Communications Engineering Lab (CEL) Dipl.-Ing. Martin Braun Research Associate Kaiserstraße 12 Building 05.01 76131 Karlsruhe Phone: +49 721 608-43790 Fax: +49 721 608-46071 www.cel.kit.edu KIT -- University of the State of Baden-Württemberg and National Laboratory of the Helmholtz Association ___ 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] How to plot(gr-utils) the complex data in gnuradio?
Hi guys, I want to observe the pattern of received signal in ofdm example, however, the signal over the air is complex type. So I want to know how to use gr-utils to plot these complex data. Thanks so much. Best, Kay ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
[Discuss-gnuradio] What is the function of fir_filter_ccc in gnuradio(synchronization process in ofdm example)?
Hi guys, I am trying to figure out how fir_filter work. In particular for the case that using fir_filter to perform cross-correlation in synchronization process. However, I read the code but still can not understand it. Please tell me if you know it. Thank you so much. *Please refer to the following code in ofdm_sync_pnac.py self.crosscorr_filter = gr.fir_filter_ccc(1, kstime) // kstime is the known symbol # Cross-correlate input signal with known preamble self.connect(self.input, self.crosscorr_filter)* Best, Kay ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
[Discuss-gnuradio] Is there any PN cross correlator implementation for packet detection in Gnuradio?
Hi guys, I noticed that Gnuradio uses schmidl PN correlator for packet detection by defalt, where the 1st copy autocorrelate with 2nd copy in one preamble. I wonder if any PN cross correlator is implemented, which means the received signal is cross correlated with known preamble stored locally. Thank you so much. Best, Kay ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
[Discuss-gnuradio] Can anyone explain the function of coarse_freq_comp in OFDM channel estimation process?
Hi guys, The gnuradio calculate the channel estimated value* d_hestimate* using the received symbol and known symbol. However, I dont know the exact meaning of *coarse_freq_comp(d_coarse_freq,1)* when performing the calculation. Can anyone explain this function? Please refer to the following formula, d_hestimate[i] = d_known_symbol[i] / (coarse_freq_comp(d_coarse_freq,1)*(symbol[i+zeros_on_left+d_coarse_freq])); Thanks in advance. Best, Kay ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] What are coase freq. estimation and fine freq. estimation in OFDM? Did the implementation in gnuradio follow the 802.11 standard?
Thanks for you reply, Tom. So what you mean is that gnuradio only use one symbol to do the time frequency (including coarse and fine)synchronization, as well as CSI estimation, is that right? You also said the coarse freq. offset estimation is slight different. Can you show me some references only related to coarse freq. offset estimation in gnuradio. Thanks in advance. Best, Kay 2013/4/15 Martin Braun (CEL) martin.br...@kit.edu On Sun, Apr 14, 2013 at 03:57:31PM +0800, Yingjie Chen wrote: Hi guys, I have check the 802.11 standard before. It said the coase freq. estimation is done in short preamble, and the fine freq. estimation is done in long premable. However, to my best knowledge, gnuradio only uses one preamble for synchronization. So how are these two freq. estimation works done in one preamble. BTW, can anyone tell me the exact different between coase one and fine one? Are they both related to the FFT bin aligning? The OFDM stuff in GNU Radio has *nothing* to do with 802.11x. It's just a more-or-less generic OFDM implementation. I very much so recommend reading the Schmidl Cox OFDM sync paper [1]; their algorithm is pretty much what is used GNU Radio. It also explains the difference between coarse and fine frequency offset (short: coarse = integer multiples of sub-carrier offset, fine=smaller than that). In the original paper, they suggest 2 symbols for synchronisation (of time frequency) as well as initial CSI estimation. This can also be done with 1 symbol, which is done in the current OFDM stack. The OFDM work that was recently added can handle both 1 or 2 sync-symbols; the estimation of the coarse freq. offset is slightly different for these cases. However, this type of sync needs modification if you want to adapt it to 802.11. MB [1] Schmidl, T.M.; Cox, D.C., Robust frequency and timing synchronization for OFDM, Communications, IEEE Transactions on , vol.45, no.12, pp.1613,1621, Dec 1997 -- Karlsruhe Institute of Technology (KIT) Communications Engineering Lab (CEL) Dipl.-Ing. Martin Braun Research Associate Kaiserstraße 12 Building 05.01 76131 Karlsruhe Phone: +49 721 608-43790 Fax: +49 721 608-46071 www.cel.kit.edu KIT -- University of the State of Baden-Württemberg and National Laboratory of the Helmholtz Association ___ 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] What are coase freq. estimation and fine freq. estimation in OFDM? Did the implementation in gnuradio follow the 802.11 standard?
Hi guys, I have check the 802.11 standard before. It said the coase freq. estimation is done in short preamble, and the fine freq. estimation is done in long premable. However, to my best knowledge, gnuradio only uses one preamble for synchronization. So how are these two freq. estimation works done in one preamble. BTW, can anyone tell me the exact different between coase one and fine one? Are they both related to the FFT bin aligning? ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] How many preambles uesd in ofdm example for frame synchronization, 10 short preambles ?
Thanks for your reply. I still have one question. I try to plot the peak detection data to observe the the shape of the peak, which seems like a plateau(square wave).I have done a simulation before in matlab. If only one preamble exist, when the 1st half of the preamble correlate with 2nd half, the shape of peak should be much sharper(like a triangle), because the repeated pattern is not enough. My question is : If gunradio only use one preamble with 2 repeated pattern, the shape of the peak should look like a triangle rather than a plateau, is that right? 2013/4/6 Tom Rondeau t...@trondeau.com On Sat, Apr 6, 2013 at 10:01 AM, Yingjie Chen ocg...@gmail.com wrote: Hi guys, Thanks in advance. In default setting, I wonder if gunradio has followed the 802.11 standand using 10 short preambles for synchronization or not. Hope anyone can tell me. No, it is not. Just a standard implementation of the Schmidl and Cox algorithm, so one preamble the same length as all other symbols with a repeated pattern in time (i.e., the first half of the symbol is repeated in the second half of the symbol). Tom ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
[Discuss-gnuradio] In ofdm example, is channel estimation work only done in one preamble per frame or each symbol per frame?
Hi guy, I am currently working on ofdm example. I try to print out the channel estimated value d_hestimate on terminal. However, I found each frame number followed several sets of channel estimated value. I feel so confused because I believe channel estimation is only done in preamble for each frame. It should be only one set of channel estimated value following one frame, is that right? ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
[Discuss-gnuradio] Why packet decode failure happen when fft-length is set to 64?
Hi guys, Thanks in advance. I am using usrp2 in OFM example. When I set fft-length to 64, subcarrier to 32,the receiver cannnot decode the packet correctly. The whole chunk of received data are almost false. However, when I set fft-length to 128, subcarriers to 64, nearly all packets can be decode correctly. I feel so confused about that. Does anyone know that? Sent from my iPhone ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
[Discuss-gnuradio] Is there any correlation between bandwidth and subcarriers-tounes in ofdm?
Hi guys, I wonder if there is any correlation between baseband bandwidth of receiver side and fft-subcarriers-tounes of sender sider in OFDM? When I set the bandwidth to 20Mhz in sender side, the spectrum analyzer of receiver side shows only half of bandwidth（10Mhz). Does the reason that I use 128fft and 64 subcarriers account for this phenomenon? Sent from my iPhone ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
[Discuss-gnuradio] OFDM Channel Estimate block ?
Hi guys, Thanks in advance. Can anyone tell me where the *channel estimate block* is in *ofdm* example? I want to extract the channel estimate value *H *I am trying to locate it, but still get lost. I believe that it should be after FFT process, is that right? Best, Kay ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
[Discuss-gnuradio] How to capture the PN_Peak value in preamble before normalization during sync in OFDM?
Hi guys, Did anyone know how to print out the PN_peak value in preamble after correlation but before normalization process? The sync file is *ofdm_sync_pn.py. *But I have no idea which block should I modify? Thanks so much Best, Kay. ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
[Discuss-gnuradio] Why nothing change after I modified some codes in C++ block and successfully compiled it?
Hi guys, Thanks in advance. I have added some codes in c++ block, like *printf(i=%d\n,z);* for output test. However, after I compiled the modified block *(.cc file)*and generated the new object file* (.cc.o file)*, nothing printed out from the terminal, which means nothing changed in the original code. But actually I did. I feel so confused, hope everyone can help me. The example I used is in */home/k/src/gnuradio/gr-digital/examples/ofdm*, and the file I modified is /home/k/src/gnuradio/build/gnuradio-core/src/lib/gengen/* gr_peak_detector_fb.cc*, which is one c++ block connected by ofdm example. Best, Kay. ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
[Discuss-gnuradio] how to compile the py file in gnuradio
Hi guys, I have checked the mailing list before, but cannot fine any useful information related to my question. I have done some modifications in ofdm.py file. And I want to rebuild or compile it, how should I do? I have try to use make install command, seems nothing happen. ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
