GNURadio OFDM multiple data in subcarriers.
Hi all, I was trying to send contents of a file using a single subcarrier in OFDM. As Marcus pointed out, it is a complex process and i found out that using a single data carrier for the main data apart from the carriers for the header and sync words, the channel estimation takes forever. The data is never decoded. What I want to do is use different subcarriers of the OFDM transmitter to send different file contents. Say use subcarrier 3, 4 to send contents of file 1 and subcarriers 7, 8 to send contents of file 2. I want to do it simultaneously. I am using USRP B200 on both. I tried using 2 flowgraphs, one for each file, in the same grc file for doing it. The transmitter seems to send the required data. I tried decoding it with the loopback flowgraph. The output was redirected to the terminal. The contents were being printed properly. But whenever I use the USRP, the receiver side just stops working. The receiver side also has 2 flowgraphs running with the corresponding values of the subcarriers. For ofdm transmitter 1, the parameter values are: Occupied carriers- ((-2, -1, 2, 1 3, 4),) Pilot carriers- ((-21, -11, 11, 21),) Pilot symbols- ((-1, 1, -1, 1),) For ofdm transmitter 2, the parameter values are: Occupied carriers- ((-4, -3, -5, -6, 6, 7),) Pilot carriers- ((-26, -25, 26, 25),) Pilot symbols- ((-1, 1, -1, 1),) I want to do it using a single flowgraph. What would be the right way to proceed with this?
Introduction
Hello Everyone, I am Satya Prakash Sasini, a final year B Tech. graduate from India. Current;lly I am working as a DevOps Intern in Devtron Inc. With my expertise in DevOps technologies and proficiency in Data Structures and Algorithms using C++ I would like to contribute to GNU Radio in this Google Summer of Codes 2024. Eager to learn and apply my skills to contribute to such a interesting open-source project. Regards Satya Prakash Sasini
Re: Transmitting on a single subcarrier
Hi Sourya, On 16.03.24 22:30, Sourya Saha wrote: I am using an OFDM transmitter and receiver blocks from GNU radio. Essentially what i want to do is split up the bandwidth into 64 subcarriers and trasmit on any one of the subcarriers, say subcarrier 3. Remark: that is just FSK, but due to the nature of OFDM an FSK with a less-than-pretty symbol shaping, and due to the cyclic prefix, an FSK with a phase jump within each symbol. *Usually*, you'd avoid doing that, and just build an FSK system. Especially, since if you only use one carrier at a time, you lose the ability to sense the channel, or use Schmidl&Cox (or similar methods) for synchronization, so there's no arguments going for OFDM here – that's why I pointed out that OFDM was a rather advanced topic, you need to understand *why* you're using it, fighting *which* channel problems. You get all the complexity, the overhead and all the problems of OFDM, without any data rate benefit. However, nothing in GNU Radio would stop you from doing that: Data vectors with a lot of zero entries and a single non-zero entry. If that is to be done, in the data carriers field of the ofdm transmitter and receiver, mentioning just '3' as the subcarrier should work. Not sure what "mentioning" means, but as described above: data vector with all zeros, but a non-zero value in the third entry. Best, Marcus
Re: Error undefined Symbol
Hi Daniel, On 18/03/2024 11.00, Daniel González Martínez wrote: > find_package(Gnuradio "3.10" REQUIRED COMPONENTS fft digital) > The following imported targets are referenced, but are missing: > gnuradio::gnuradio-filter gnuradio::gnuradio-blocks > gnuradio::gnuradio-analog > > It is a problem with digital library, but I don't know how to fix it. You need to add filter, blocks and analog to to Gnuradio COMPONENTS list: find_package(Gnuradio "3.10" REQUIRED COMPONENTS filter blocks analog fft digital) Regards, Vasil
Error Cmake
Hi, When I try to fix the undifined symbol using: target_link_libraries(gnuradio-blockcheck gnuradio::gnuradio-runtime gnuradio::gnuradio-fft gnuradio::gnuradio-digital) find_package(Gnuradio "3.10" REQUIRED COMPONENTS fft digital) But I have this error: CMake Error at CMakeLists.txt:37 (find_package): Found package configuration file: /usr/local/lib/cmake/gnuradio/GnuradioConfig.cmake but it set Gnuradio_FOUND to FALSE so package "Gnuradio" is considered to be NOT FOUND. Reason given by package: The following imported targets are referenced, but are missing: gnuradio::gnuradio-filter gnuradio::gnuradio-blocks gnuradio::gnuradio-analog It is a problem with digital library, but I don't know how to fix it.
