Re: [Discuss-gnuradio] measuring RSSI - N210 with RFX2400

[Kresimir Dabcevic]

-----Original Message-----
From: address@hidden on behalf of Josh Blum
Sent: Sat 6/4/2011 8:04 PM
To: address@hidden
Subject: Re: [Discuss-gnuradio] measuring RSSI - N210 with RFX2400

>
> There is an "rssi" sensor:
> http://www.ettus.com/uhd_docs/manual/html/dboards.html#rfx-series
>
> from the uhd api:
> usrp->get_rx_sensor("rssi")
>
> or in python w/ gr-uhd
> usrp.get_dboard_sensor("rssi")
>
> -josh
>

Thanks for the answer Josh.

As for the analog RSSI, I am quite confused because calling self.u.get_dboard_sensor("rssi")
from the top block (right after defining "u" as uhd usrp source) is giving me a value around
6 dBm, regardless of whether I am transmitting a signal or not. Also, when I call
self.u.get_dboard_sensor("rssi") again immediately after that, new "RSSI" is about 2-3 dB
higher - what happens here?

When I tried:
    global tb   
    tb = oqpsk_rx_graph(options, rx_callback)

where oqpsk_rx_graph is the class in which gr.top_block is initialized, and rx_callback
subprogram which is executed when (OQPSK modulated) package is received, and then within
rx_callback calling:
    tb.u.get_dboard_sensor("rssi"),
the sensor says the RSSI is always either 17.033812 dBm or 17.108199 dBm, regardless of my TX
power or RX gain - what am I doing wrong here?

Also, is there a possibility to somehow measure RSSI with analog sensor at the exact same moment
when we are receiving package - I am aware that with the above command I am calling the function
after the package was received (so measuring RSSI doesn't make sense, even though it should still
differ from the two values I am getting)?...

Regards,
Kresimir Dabcevic