LFRX Gain settings

Anyone know what the allowable gain settings are when using the USRP
with the LFRX daughterboard? I believe I read somewhere that 20 is the
default and units are dB, but what are the min/recommended/max values?
I tried digging them out of usrp1_source_c.cc, usrp1_source_base.cc, and
usrp_standard.cc (all from rel 3.0.3) but had no luck.

GRC seems to default it to 100, but this seems pretty high if the
setting is in dB.

@(^.^)@ Ed

Ed Criscuolo wrote:

Anyone know what the allowable gain settings are when using the USRP
with the LFRX daughterboard? I believe I read somewhere that 20 is
the default and units are dB, but what are the min/recommended/max
values? I tried digging them out of usrp1_source_c.cc,
usrp1_source_base.cc, and usrp_standard.cc (all from rel 3.0.3) but
had no luck.

The allowable gain range for the LFRX is 0 to 20.

The LFRX board has no inherent gain itself; what you are actually
adjusting is the programmable gain amplifier at the input to the
motherboard AD9862 ADC. You are setting the ADC full-scale value to 2V
p-p when gain is set to 0, and at 0.2V p-p when gain is set to 20.


Johnathan C.
Corgan Enterprises LLC
http://corganenterprises.com