Question about Packet Length in OFDM transmission
Hello Everyone, I was trying to simulate an OFDM transmission using OFDM Tx and Rx files given in the example folder. I added both tx and rx part in same flowgraph. I added a ".txt" file size of 100 bytes as source and wanted to receive it at the sink. In my case, If I set packet length to only 1 then full bytes are received at the Rx end. I saw few others example from different sources who used different packet lengths for packet transmission and getting their outputs. In my case, what am I missing? Would appreciate, if anyone explain to me. I added my flowgraph in attachment. Thanks in advance. -- Regards, Rupak Paul tx_ofdm_loopback.grc Description: Binary data
Re: OFDM cannot receive the correct number of packets
Hi, I am not an expert at this but you can set packet length to 1 and then try or you can modify OC and PC. It worked for me. Regards, Rupak On Thu, Nov 4, 2021 at 2:33 PM 能书能言 <2127629...@qq.com> wrote: > HI, > Recently I am conducting some ofdm experiments, using the example > ofdm_tx/rx.grc and two USRPB210s, but I found that when the number of data > packets I send is small (about ten or less), I can receive at the receiving > end To the same number of packets. But when I increase the number of sent > packets to about a few hundred, the number of received packets will be less > than the number of sent packets, but occasionally their numbers will be > equal. At first I thought it was caused by the too short sending and > receiving time, but when I increased the sending and receiving time, > occasionally the number of the two could be the same. Most of the time it > was different. What is the cause of the phenomenon? Is it a USRP > sampling problem? How should I ensure that the number of data packets > sent is the same as the number of received data packets each time? Is it > really because of the time of sending and receiving? > > I found that the amplitude of USRP is limited to the range of (-1, 1). If > the "multiply const" setting is incorrect, will the receiver fail to detect > the start of the data packet correctly, which causes this problem? > > But why doesn't this error occur when the number of data packets is > relatively small? Because the number of FFT transforms does not change, > and the modulation method is also fixed at the four constellation points, > theoretically, there should be no problems caused by the change in the > number of data packets? > > Sincerely > Thanks! >
Re: Why the ofdm data packet is not fully received ?
Hello there, Thanks for your explanation. As this discussion is going on, I want to add my questions here too. - Should I redesign Occupied Carrier size or Packet length every time depending on my data size? It seems if I set the packet length to 1 then it transfers all data regardless of any data size. - What is the purpose of that Delay block at the beginning of the receiver? Is it related to cycle prefix removal? Thank you. BR, Rupak On Thu, Oct 28, 2021 at 2:33 PM Marcus Müller wrote: > Hi! > > A single OFDM symbol has 64 carriers. I can only guess you're using the > configuration of OFDM Carrier Aggregator that gives you 48 carriers > dedicated to data. > On each of these carriers, you do QPSK, so 2 bit per symbol. > That makes for a total of 96 bits, in a single OFDM symbol. > > 96 bits are 12 Bytes. "hello world" has 11 Bytes. So, you're not even > filling a single OFDM symbol with data! > > But you're even setting a frame length of 96 bytes. So, this can't work; > you need to give the transmitter enough data to fill a frame. > > Best regards, > Marcus > > > > On 28/10/2021 10.59, 能书能言 wrote: > > Hello everyone, > > I am using ofdm_tx/rx.grc to transfer text file data, and there is a > > "hello world" character in the text. I use two usrpb210 for transmission > > .When I set the "repeat" in the "file sink" to no, the receiving end > > cannot receive the correct "hello world" word, and the open file is > > blank; but when I set the "repeat" to yes, the receiving file is opened > > , Which contains a lot of repeated "hello world" words, I want to know > > why this happens? How can I solve this problem? (It can still be > > received correctly when my "repeat" is set to no) > > The flowchart is in the attachment. > > Thanks to anyone for the relevant information, thank you! > > Sincerely > -- Regards, Rupak Paul
Problem in modifying OFDM transmitter block (v3.8)
Dear Community, I am trying to modify the OFDM transmitter block by adding one more payload modulation (16-QAM). In the python file, I added the following line in the "def_get_constellation (bps)" section as well as edited the yml file respectively and it's built successfully. " digital.constellation_16qam() " But when I try to use this block with 16QAM modulation in the example OFDM grc file, it says "Modulation not supported". Though, BPSK, QPSK work fine with the same new block. Am I missing something? Waiting for your suggestions. Thank you. -- Regards, Rupak Paul
Re: Unable to add FMCOMMS5 from git library
Hi Marcus, Thanks for your suggestion. Actually I had my old projects on older version 3.7 on both Ubuntu and Windows. Will download new versions and try again. Thanks. Regards, Rupak On Sun, Jan 24, 2021 at 11:58 PM Marcus Müller wrote: > Hi Rupak, > > this makes no sense: ADI put a lot of effort into getting gr-iio to work > with GNU Radio > 3.8, and porting efforts to 3.9 are at least underway. > > It absolutely makes no sense to use GNU Radio 3.7 on a new project, > especially since > multiple of its dependencies have gone end-of-life. You can trivially > upgrade to GNU Radio > 3.8 using GNU Radio's own PPA, or from Ubuntu's own package repositories > if you upgrade > your Ubuntu 20.04. > > If you've already got working infrastructure based on GNU Radio 3.7, the > situation is > different: we do take a bit of caution to help 3.7 keep running on legacy > systems. We are, > however, not porting it to new platforms (which simply doesn't work due to > the > dependencies mentioned above), and I'd certainly recommend not starting a > project with 3.7 > in 2021. > > Best regards, > Marcus > > On 24.01.21 23:33, Rupak Paul wrote: > > Hello there, > > I am using Gnuradio v3.7 in linux 18.04. But I can't find FMCOMMS5 block > in this version. > > I tried to add it from github library using "git clone > > https://github.com/analogdevicesinc/gr-iio.git > > <https://github.com/analogdevicesinc/gr-iio.git>" > > but didn't work either. > > > > Anybody please guide me, how to add it by using gr_modtool or from > github library? > > > > -- > > > > > > Regards, > > Rupak Paul > > > > -- Regards, Rupak Paul
Unable to add FMCOMMS5 from git library
Hello there, I am using Gnuradio v3.7 in linux 18.04. But I can't find FMCOMMS5 block in this version. I tried to add it from github library using "git clone https://github.com/analogdevicesinc/gr-iio.git; but didn't work either. Anybody please guide me, how to add it by using gr_modtool or from github library? -- Regards, Rupak Paul
Unable to compile OOT module block from gr-digital
Hello there, I am trying to compile a given block named "ofdm_carrier_allocator_cvc" from "github/gnuradio/gr-digital". After going through the "make test" I got some error like this, Traceback (most recent call last): 2: File "/home/rupak/gr-OFDM/python/qa_ofdm_mod.py", line 54, in test_001_t 2: self.tsb_key) 2: TypeError: __init__() takes at most 4 arguments (7 given) ... And I got this same error msg from every test cases used in this file. Though I didn't modify anything in "__init__.py" file. N.B. I edited below files to extract this block. python/qa_ofdm_mod.py include/ofdm_mod.h lib/ofdm_mod_impl.h lib/ofdm_mod_impl.cc Appreciate any kind of suggestions. Thanks!! Regards, Rupak
Makefile:127: recipe for target 'test' failed during 'make test' command
Hi there, I am using Ubuntu 16.08 and GNU 3.8. When I run ''make test'' cmd for creating new OOT module, it fails and shows- .. Running tests... Test project /home/rupak/gr-howto/build Start 1: test_howto 1/2 Test #1: test_howto ... Passed0.02 sec Start 2: qa_square_ff 2/2 Test #2: qa_square_ff .***Failed0.42 sec 50% tests passed, 1 tests failed out of 2 Total Test time (real) = 0.44 sec The following tests FAILED: 2 - qa_square_ff (Failed) Errors while running CTest Makefile:127: recipe for target 'test' failed make: *** [test] Error 8 ... I followed every steps according to 'OutOfTreeModules'. How can I fix this issue? -- Thanking you, Rupak Paul
How to run gr-howto Python or C++ files from ubuntu
Hi, I am new in this platform and trying to run my first block in Gnu Radio. Using tutorial script from OOT modules, I am unable to run C++ or Python files (e.g. qa_square_ff.py) from cmd window. When I use "python3 qa_square_ff.py" command, it always says some module (e.g. howto_swig) is missing. Is there any step by step guideline to run this type file from cmd window? Regards, Rupak
