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From: | Marcus Müller |
Subject: | Re: [Discuss-gnuradio] USRP B210 TX gain |
Date: | Mon, 3 Aug 2015 09:23:00 +0200 |
User-agent: | Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.1.0 |
I'd also like to chip in that effective TX power is very
dependent on frequency for devices that span several orders of
magnitude in frequency -- so you can't just say "the max TX power is
x dBm", you need to measure for every frequency, with every
bandwidth you use, for the specific signals you transmit; often,
application-specific aspects define what TX power is, and it's not
always trivial to say what TX power means -- for example, the B210
being good, but not perfect, it of course has emissions a) inside f_target +-/f_sample/2 (intentional) b) outside a) but close to it c) further away how much bandwidth do you observe when saying "TX power is x dBm"? a) only? That might make sense from a specific receiver's perspective, but not do a pure RX power observation right. a+b+c) ? Impossible to measure. a+b) makes sense if you're really interested in how much power leaves the device (e.g. for legal limits), but really depends a lot on factors like how you tune, what sampling rates you're using etc. This all contributes to the fact that when determining the signal strength, you must first careful define what you want to describe, and then measure it. Best regards, Marcus On 02.08.2015 21:09, Marcus D. Leech
wrote:
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