From: Prashant Laddha Date: Wed, 4 Feb 2015 09:07:32 +0000 (-0300) Subject: [media] vivid sdr: fix broken sine tone generated for sdr FM X-Git-Tag: firefly_0821_release~176^2~795^2~1342 X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=d585c1e14a84f08a4a714553d9fc459ee697ff95;p=firefly-linux-kernel-4.4.55.git [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 Signed-off-by: Prashant Laddha Signed-off-by: Hans Verkuil Signed-off-by: Mauro Carvalho Chehab --- diff --git a/drivers/media/platform/vivid/vivid-sdr-cap.c b/drivers/media/platform/vivid/vivid-sdr-cap.c index 5e089cb58a38..caf131666e37 100644 --- a/drivers/media/platform/vivid/vivid-sdr-cap.c +++ b/drivers/media/platform/vivid/vivid-sdr-cap.c @@ -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