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From: | Marcus Müller |
Subject: | Re: [Discuss-gnuradio] Editing usrp_spectrum_sense.py |
Date: | Tue, 22 Mar 2016 21:10:38 +0100 |
User-agent: | Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.6.0 |
Dear Fikrat, the physical power depends on your waveform. Generally, the power is always , which, thanks to Ohm's law () is . As you might know from the basics of electrical engineering, one can represent harmonic functions such as a voltage sine generated by a function generator as complex number with magnitude and phase , i.e. as ; notice that for the power consideration, you can omit the , it always having the magnitude 1. Use your math basics to find the average power by integrating over a period. For harmonic signals you'll find that if you set . 2. Moreover, am I supposed to connect the signal generator directly to the TX/RX port?If you can make sure your signal generator doesn't push more than -15dBm into the USRP, then sure. Otherwise, use a calibrated attenuator and adjust your measurement. I don't know which signal generator you use, but most RF signal generators I know accept both, either voltage/amplitude or power as setting. Also make sure your signal generator is set to 50Ohm impedance, if that is adjustable. 3. Finally, if that was the case, how do I observe the digital power on the USRP n210?Well, the magnitude of the imaginary and real part of the digital samples are proportional to the voltage on the I and Q input of the ADC... Soooo: Digital power is just I²+Q² = |s|², the magnitude squared. All in all, these are pretty basic questions; we're constantly working on making GNU Radio more beginner-friendly, but to do that, we might at times need to refer people to adequate literature. So: May I ask what background you come from? Best regards, Marcus PS: could you also try to keep the address@hidden mailing list at least in CC:? It's always better to ask the whole list instead of individual people. I might not always have the time... On 22.03.2016 17:48, Fikrat Al-Kazimi
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