Hello Trang: Then you can probably start with energy detection. Just tune to the channel that you intend to check, collect samples, take FFT -> mag^2 (optional), then check whether the power level of the channel stays below some level for a pre-defined length of time. If it stays under that level, you claim that the channel is available (occupied otherwise). Once that's done, you can hop to the next channel and repeat the whole proces.
Just search something like "usrp energy detection" or "usrp cognitive radio" on your search engines, and you will see some articles regarding this. Please note that this is probably not an acceptable practice on some bands. For Wi-Fi bands, this is probably acceptable (because those bands are intended for unlicensed uses anyway). Regards, Kyeong Su Shin ________________________________ 보낸 사람: My St via USRP-users <usrp-users@lists.ettus.com> 대신 USRP-users <usrp-users-boun...@lists.ettus.com> 보낸 날짜: 2020년 10월 21일 수요일 오전 7:57 받는 사람: Marcus D. Leech <patchvonbr...@gmail.com> 참조: usrp-users@lists.ettus.com <usrp-users@lists.ettus.com> 제목: Re: [USRP-users] spectrum availability measurement with usrp Dear Kyeong and Marcus, Thank you very much for your answers which help me to see better the challenges. I intend to start with Wi-Fi signals. We have a lot of Wi-Fi networks around us and I want to show the occupation/availability of Wi-Fi channels. I also intend to use gnu-radio. With best regards, Trang Nguyen Le mar. 20 oct. 2020 à 07:37, Marcus D. Leech via USRP-users <usrp-users@lists.ettus.com<mailto:usrp-users@lists.ettus.com>> a écrit : On 10/20/2020 01:05 AM, Kyeong Su Shin via USRP-users wrote: Hello Trang: It depends on your applications. USRPs CAN be used to scan and map the wireless spectrum, but you will have to determine whether the spectrum is empty or not, and it is not a trivial question. For an example, signals from satellites and spacecrafts are often below the thermal noise, so you will need to use special dish antennas and/or correlate the signals with known sequences in order to detect them. Also, USRP B200/B210 are not high-end spectrum analyzers, so they may show you some spurious signals (possible false positives). So, yes, it is possible, but I don't know whether they are suitable for your use cases. Regards, Kyeong Su Shin ________________________________ Some further wisdom. SDRs are *components* in an overall engineered RF *system and application*. They aren't "born" knowing your particular application. You'll need some non-trivial knowledge of software development methodologies, DSP knowledge, and knowledge of radio and electronics to develop an application that suits your needs. Now, there are lots of applications for SDRs in general out there. I'd suggest you query the discuss-gnuradio mailing list as well. But don't be surprised to find that an application that fits precisely what you want to do doesn't exist. Consider two things: The set that could be described as "useful things you might want to do with radio technology" The set that could be described as "useful things you might want to do with a computer" Both of those sets are staggeringly large. So even an intersection will also be staggeringly large. So it should not perhaps be surprising that not everything that could possibly be done with this technology has already been invented, and conveniently packaged. _______________________________________________ USRP-users mailing list USRP-users@lists.ettus.com<mailto:USRP-users@lists.ettus.com> http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com
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