Transceiver52M: Narrow resampling filter bandwidth
Transceiver52M: Narrow resampling filter bandwidth

This patch only applies to resampling use at 4 samples-per-symbol.
By extention that means only USRP2 / N2xx devices are affected.
At 4 samples-per-symbol we restrict output bandwidth to roughly
roughly 700 MHz, which combined with the 2 pulse Laurent
approximation yields < 0.5 degrees of RMS phase error at the
resampler output.

Signed-off-by: Thomas Tsou <tom@tsou.cc>

git-svn-id: 504cad4147f1e500be0a169b9f46375eaf875953@6742 19bc5d8c-e614-43d4-8b26-e1612bc8e597

xyzr0482/openbts,dhenyjarasandy/openbts,Djimmer/obts,hongyunnchen/openbts,endaga/openbts,xyzr0482/openbts,xyzr0482/openbts,hongyunnchen/openbts,dhenyjarasandy/openbts,WindyCitySDR/openbts,maxifree/openbts,Djimmer/obts,RangeNetworks/openbts,dhenyjarasandy/openbts,RangeNetworks/openbts,maxifree/openbts,brunoflce/pessoalopenBTS,endaga/openbts,hongyunnchen/openbts,WindyCitySDR/openbts,brunoflce/pessoalopenBTS,hongyunnchen/openbts,WindyCitySDR/openbts,hongyunnchen/openbts,Djimmer/obts,endaga/openbts,Djimmer/obts,brunoflce/pessoalopenBTS,RangeNetworks/openbts,WindyCitySDR/openbts,maxifree/openbts,RangeNetworks/openbts,maxifree/openbts,WindyCitySDR/openbts,brunoflce/pessoalopenBTS,brunoflce/pessoalopenBTS,maxifree/openbts,dhenyjarasandy/openbts,xyzr0482/openbts,Djimmer/obts,RangeNetworks/openbts,endaga/openbts,Djimmer/obts,xyzr0482/openbts,dhenyjarasandy/openbts,endaga/openbts,RangeNetworks/openbts