On real devices, signal strength is always a negative
number when represented in dBm. A more interesting
range is to use dBmV (which is what Kaffeine does,
for example). The conversion from the two units are
simple:
dBmV = dBm - 108
Usually, signal strength ranges up to 100dBmV. Adjust the
maximum value to be around 74 dBmV, when there's no
frequency shift, which represents a good signal.
With that, Kaffeine displays it a lot better.
Signed-off-by: Mauro Carvalho Chehab <mchehab+hua...@kernel.org>
---
drivers/media/test-drivers/vidtv/vidtv_demod.c | 12 +++++++++---
1 file changed, 9 insertions(+), 3 deletions(-)
diff --git a/drivers/media/test-drivers/vidtv/vidtv_demod.c
b/drivers/media/test-drivers/vidtv/vidtv_demod.c
index c54c88cac84f..c825842758f0 100644
--- a/drivers/media/test-drivers/vidtv/vidtv_demod.c
+++ b/drivers/media/test-drivers/vidtv/vidtv_demod.c
@@ -181,12 +181,18 @@ static void vidtv_demod_update_stats(struct dvb_frontend
*fe)
c->block_count.stat[0].scale = scale;
/*
- * Add a 0.5% of randomness at the signal streangth and CNR,
+ * Add a 0.5% of randomness at the signal strength and CNR,
* and make them different, as we want to have something closer
* to a real case scenario.
+ *
+ * Also, usually, signal strength is a negative number in dBm.
*/
- c->strength.stat[0].svalue = state->tuner_cnr +
prandom_u32_max(state->tuner_cnr / 50);
- c->cnr.stat[0].svalue = state->tuner_cnr -
prandom_u32_max(state->tuner_cnr / 50);
+ c->strength.stat[0].svalue = state->tuner_cnr;
+ c->strength.stat[0].svalue -= prandom_u32_max(state->tuner_cnr / 50);
+ c->strength.stat[0].svalue -= 68000; /* Adjust to a better range */
+
+ c->cnr.stat[0].svalue = state->tuner_cnr;
+ c->cnr.stat[0].svalue -= prandom_u32_max(state->tuner_cnr / 50);
}
--
2.26.2
