B200 has a max output power of ~ 15 dBm (give or take) in max gain (89 dB), depending on the frequency, and a max input power of 0 dBm. To be on the safe side, you can and should take a 10 dB backoff, so for the sake of discussion, assume the max input power is -10 dBm.
You can use the Free Space Path Loss formula (calculator: https://www.pasternack.com/t-calculator-fspl.aspx) to get a sense (the formula is for the free space) of how much power you "lose" by using a wireless channel, the results depend on your choice of frequency and distance between antennas. You need to make sure the antennas are "far" enough to be on the far field of each other. You can also take into account the attenuation the SMA cables add on both sides, or, to save you all of the trouble, you can just transmit with a gain low enough such that the transmitted signal is weaker than the max input power (i.e., if 89 dB tx gain is ~ 15 dBm, then 49 dB tx gain is ~ -25 dBm, so you're good), and/or you can put a 30 dB attenuator either in the tx or rx port, that way you'll know that even if you make a software mistake, you're on the safe side. On Sun, Mar 4, 2018 at 3:38 AM Christopher Richardson via USRP-users < [email protected]> wrote: > Hi, > > I'm just wondering if anyone could give me some advice, I'm using the USRP > B200 with GNU Radio with a simple FM example to transmit and receive on > the same frequency. > > I made use of telescopic whip antennas on the Tx port and another on the > Rx port, I had the antennas tilted away from each other, but I've been > informed this could still be a bad idea and could overload the receiver? (I > had also played with different Rx/Tx gain values while testing this). > > I'm just hoping I haven't damaged anything. > > I'm planning on now getting 2x 3 metre SMA cables to separate the antennas > by around 6 metres, does this seem sensible? > > Cheers > > Chris > _______________________________________________ > USRP-users mailing list > [email protected] > http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com >
_______________________________________________ USRP-users mailing list [email protected] http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com
