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[media] vivid sdr: fix broken sine tone generated for sdr FM 

FM (frequency modulated) signal for SDR is generated by varying the
phase, where phase variation is proportional to input signal. It is
seen that, the larger phase increments leads to discontinuities in
the signal recovered after demodulation. Reducing the extent of phase
variation with respect to input signal, equivalent to reducing the
modulation index.

Tested using FM receiver flow graph in gnuradio-companion.

Cc: Antti Palosaari <crope@iki.fi>
Signed-off-by: Prashant Laddha <prladdha@cisco.com>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
This commit is contained in:
Prashant Laddha 2015-02-04 06:07:32 -03:00 committed by Mauro Carvalho Chehab
parent 4e30a37345
commit d585c1e14a
1 changed files with 1 additions and 1 deletions
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2
drivers/media/platform/vivid/vivid-sdr-cap.c
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@ -454,7 +454,7 @@ void vivid_sdr_cap_process(struct vivid_dev *dev, struct vivid_buffer *buf)
FIXP_2PI) >> (31 - FIXP_N);
dev->sdr_fixp_src_phase += src_phase_step;
dev->sdr_fixp_mod_phase += mod_phase_step;
dev->sdr_fixp_mod_phase += mod_phase_step / 4;
/*
* Transfer phases to [0 / 2xPI] in order to avoid variable