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sigproc: Match differential GMSK start/end bits to tail bits 

Invert the initial and trailing diffential bits in the 4 sps
GMSK modulator to fix power-time mask irregularity at start
and end of burst. GSM tail bits are always zero, so we can
safely use fixed bit values.

Signed-off-by: Tom Tsou <tom.tsou@ettus.com>
This commit is contained in:
Tom Tsou 2016-08-11 14:36:23 -07:00
parent 2e5e2c537b
commit aa15d62a8c
1 changed files with 4 additions and 4 deletions
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8
Transceiver52M/sigProcLib.cpp
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@ -816,8 +816,8 @@ static signalVector *modulateBurstLaurent(const BitVector &bits)
c1_burst->isReal(true);
c1_itr = c1_burst->begin();
/* Padded differential start bits */
*c0_itr = 2.0 * (0x01 & 0x01) - 1.0;
/* Padded differential tail bits */
*c0_itr = 2.0 * (0x00 & 0x01) - 1.0;
c0_itr += sps;
/* Main burst bits */
@ -826,8 +826,8 @@ static signalVector *modulateBurstLaurent(const BitVector &bits)
c0_itr += sps;
}
/* Padded differential end bits */
*c0_itr = 2.0 * (0x01 & 0x01) - 1.0;
/* Padded differential tail bits */
*c0_itr = 2.0 * (0x00 & 0x01) - 1.0;
/* Generate C0 phase coefficients */
GMSKRotate(*c0_burst, sps);