# Received power measurement **URL:** \ **Category:** GNU Radio\ **Created:** [March 26, 2014, 12:09pm UTC](https://www.ruby-forum.com/t/received-power-measurement/240070 "2014-03-26T12:09:04Z")\ **Posts on this page:** 4\ **Page:** 1
**Author:** ![musicdenotation](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/m/ea666f/32.png) [@musicdenotation](https://www.ruby-forum.com/u/musicdenotation)\ **Post date:** [March 26, 2014, 12:09pm UTC](https://www.ruby-forum.com/t/received-power-measurement/240070/1 "2014-03-26T12:09:04Z")
Hi all, I need to know if there is any method to measure the received signal power using USRP N210. I am using gr\_probe\_avg\_mag\_sqrd\_x\_0 to measure the signal strength, however, the results are not accurate. Thanks ---
**Author:** ![medhat\_h](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/m/87869e/32.png) [@medhat\_h](https://www.ruby-forum.com/u/medhat_h)\ **Post date:** [March 26, 2014, 1:31pm UTC](https://www.ruby-forum.com/t/received-power-measurement/240070/2 "2014-03-26T13:31:00Z")
Is there any reason that this isn’t done at a few frequencies during manufacturing and provided in the datasheet? I’ve noticed this with a few SDR’s. Surely, it would provide a ballpark figure for those who could not afford expensive test equipment. ---
**Author:** ![medhat\_h](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/m/87869e/32.png) [@medhat\_h](https://www.ruby-forum.com/u/medhat_h)\ **Post date:** [March 26, 2014, 1:25pm UTC](https://www.ruby-forum.com/t/received-power-measurement/240070/3 "2014-03-26T13:25:44Z")
On 03/26/2014 07:04 AM, Medhat Hamdy wrote: > * * * > > Discuss-gnuradio mailing list > [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) > [Discuss-gnuradio Info Page](https://lists.gnu.org/mailman/listinfo/discuss-gnuradio) > To get accurate readings, you have to calibrate with an external, known, > source. ---
**Author:** ![medhat\_h](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/m/87869e/32.png) [@medhat\_h](https://www.ruby-forum.com/u/medhat_h)\ **Post date:** [March 26, 2014, 1:52pm UTC](https://www.ruby-forum.com/t/received-power-measurement/240070/4 "2014-03-26T13:52:05Z")
-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Hi Vanush, good question, actually. The point here (that I try to highlight whenever a question about received signal strength / RSSI / RX power requirement comes up) is that received signal strength is so much depending on what you are trying to measure, and how you go about to do that. Although I agree that something like a table saying “tuned to 1.284GHz, for the daughterboard YMCA in revision 42 in combination with the onboard ADC of the ettus b430 USRP, sampling a expensively generated noise that looks white for the complete ADC bandwidth, for which the perfectly matched signal generator proclaims that the accumulated power is -15dBm, should yield, given the following combination of filter and sampling rate settings, an average magnitude of 0.2-0.3, assuming that you have self-calibrated the USRP well enough” can be useful - but only if your application looks similar enough to the benchmark; which it usually won’t. These tables will be big. And of limited helpfulness - in the end, the user has to calibrate things himself; if there is no high-end equipment at the user’s site, then there’s no way to measure e.g. matching of antennas, quality of cabling… However: Medhat, you just said the results were “inaccurate”; maybe if he elaborated on that, we’d know what you were trying to measure. In fact, the results of avg\_mag\_sqrd are accurate to the point of numerical accuracy if you’re measuring the average numerical power of the digital domain sample – but I do get the feeling that is not what you’re trying to do. Greetings, Marcus On 26.03.2014 13:29, Vanush V. wrote: > > \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ Discuss-gnuradio > > mailing [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid)://lists.gnu.org/mailman/listinfo/discuss-gnuradio > > To get accurate readings, you have to calibrate with an external, known, > \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ Discuss-gnuradio > mailing list [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) > [Discuss-gnuradio Info Page](https://lists.gnu.org/mailman/listinfo/discuss-gnuradio) -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 Comment: Using GnuPG with Thunderbird - [http://www.enigmail.net/](http://www.enigmail.net/) iQEcBAEBAgAGBQJTMs0QAAoJEBQ6EdjyzlHtN7cIAI9gH3BlTwhAlbu/lNT9/SlD 7QPgtztf9/ywy9Ark5yjO+ncZExEEzqk/xrLn63mhGDYp4q1aWLywZldjcxDjcJm TYLyNobM6VQZFz3yShaoYwPWtq+QcMftDIC+lEJulVG8vv3ZYBXiq8A0wBwpCNEc Bfi9kWGTB2K5kBhn9w0iEyWimfJELMvxfuwPhrdpvbNSS8MQdDlieGiu/LURHmTf mCDBMplRIbQMDLczx+1oVKkP/prLJfpQBgetgglcEVdSBZ59VmTM4FrzfT7Q8sNN x91bYAKxfUDTa7f6swcKRW+wGUsbWmAw7/7Lm6afQkbcmczXNwC33c+8FxZrTsc= =wM2W -----END PGP SIGNATURE-----