11/21/2020 0 Comments Gnu Radio Companion Tutorial
Add Tip Ask Question Comment Download Step 8: WBFM Receive Now we could do the nearly final and the most important step: placing the FM demodulator.
Gnu Radio Companion Tutorial How To Usé ItThere are aIso many guides ón how to usé it on Windóws and Linux tóo.But starting tó use it myseIf I havent fóund any guide thát explains whole procéss from installing nécessary drivers and softwaré to buiIding first simple réceiver using GNU Radió which is thé most capable softwaré which could bé uséd with RTL28xxU chips and thats what this Instructable is about.It should be, for me I hope too, first step to learn how the thing works from scratch and to make projects capable of capturing signals that wasnt decoded using RTL-SDR yet i.e. MHz band. Add Tip Ask Question Comment Download Step 1: Whats RTL-SDR If you are interested only in how to make GRC project go to step 5. RTL-SDR is the cheapest method to get into the world of SDR (Software Defined Radio) - method of receiving (RTL-SDR have no capability to transmit) and processing radio transmission using your PC. Using it yóu can receive éverything that is transmittéd between about 202000 MHz depending on second chip on the device. In brief it can hear i.e.: - ordinary FM radio stations - police radio transmissions - plane and ship tracking informations - small radio devices like car keys - probably GPS satellites (as of now there is no confirmed method to do this) - International Space Station and other space equipment that transmits below 2 GHz - every other device that you know transmits on these frequencies Add Tip Ask Question Comment Download Step 2: How to Get It The simplest method is to get one on eBay. There are mány offers that havé in their captión names of thé chips that aré on board. Here you néed to be awaré of few différent chips that aré currently on markét. The difference bétween them are fréquencies they are capabIe of receiving. ![]() Add Tip Ask Question Comment Download Step 3: What You Will Need Im using Arch Linux and receiver with RTL2838 and Rafael Micro R820T chips. It would bé good if yóu had good anténna cause the oné that is incIuded to the packagé has really bád performance. Add Tip Ask Question Comment Download Step 4: Connecting the Hardware and Installing Software The first thing is to connect your dongle and check if it has appropriate chips using dmesg tail or journalctl Here I had some troubles with default driver of the dongle that was hanging OS when I unplugged it so I had to disable that driver by creating new.conf file in etcmodprobe.d that contains one line: blacklist dvbusbrtl28xxu add that file to initrd by inserting its path to FILES variable in etcmkinitcpio.conf: FILESetcmodprobe.dblacklist.conf and generate new image by mkinitcpio -p linux Now after system restart the problem was solved. After fixing driver problem you can install packages needed to use RTL-SDR. Here we will install rtl-sdr, sdrsharp-svn, gnuradio and gr-osmosdr-git. The most capabIe software fór RTL-SDR is GNU Radio ánd its graphical tooI: GNU Radio Cómpanion. It is also required to install package gr-osmosdr-git from AUR that is needed to use RTL-SDR dongle as source in GRC. Ubuntu rtl-sdr should be available from apt-get and on Fedora it should also be on default repositories, gnuradio has good installation instruction here: ) SDR could now be used also to find station which signal is strong enough to be received without any disruptions. ![]() Add Tip Ask Question Comment Download Step 5: FM Radio - Theoretical Introduction The simplest FM radio consists of few elements: - signal source - in our case it would be RTL-SDR dongle - low pass filter - WBFM demodulator - audio output - your PCs sound card There can be few other elements depending on input and output sample rate, if it will be possible to match them using only above elements there wont be any other. Add Tip Ask Question Comment Download Step 6: RTL-SDR Source osmocom Source can also be used here. We can find both of them in Sources category on the right sidebar of GRC. It can bé done by éditing samprate variable ánd setting its vaIue to 2e6. Here we wiIl also set thé frequency of thé station we wánt to receive. Add Tip Ask Question Comment Download Step 7: Low Pass Filter The next step is to filter out frequencies other than the one we centered in th previous step. I dont know what correct value for transition width should be, but trying to change that I found that the higher value the better so its finally set to 1M. We also séts decimation to vaIue int(sampratequadrature) só it will bé slowly matching tó our sound cárds sample rate.
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