tree e6440fa36c9772be786d3a707879dcfecab0e789
parent 5cd70dc4ec6a658c2835c805a8b941351c90ccb0
author Tom Tsou <tom.tsou@ettus.com> 1457262481 -0800
committer Tom Tsou <tom.tsou@ettus.com> 1457324967 -0800

EDGE: Add 8-PSK modulator and demodulator

Setup correlator and detection process similar to the GMSK
receiver chain. Require 4 SPS sampling on both Rx and Tx paths
as 1 SPS sampling adds too much distoration for 8-PSK recovery.
Core receiver operations still run at 1 SPS with the exception
of fractional delay filtering, which runs at the higher rate.

Perform linear equalization to handle the Gaussian pulse
induced ISI. The fixed impulse response used for equalizer tap
calculation consists of combined EDGE pulse shape filter and
effects of the downsampling filter. Note that the non-adaptive
equalizer corrects for modulation induced band limiting and
does not account for or compensate for fading channel effects.

Signed-off-by: Tom Tsou <tom.tsou@ettus.com>