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FS#8151 - Signal strength meter for FM radio
Attached to Project:
Rockbox
Opened by Przemysław Hołubowski (p.h.) - Tuesday, 13 November 2007, 21:28 GMT+2
Opened by Przemysław Hołubowski (p.h.) - Tuesday, 13 November 2007, 21:28 GMT+2
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DetailsThe patch adds a line showing signal strength to a tuner's screen. The line looks like this: "Field strength: 54 dBu".
It's for players having TEA5767 or LV24020. I've tested the patch on my H10. Unfortunately TEA5767 updates its field strength meter register only on station change. I don't know how LV24020 behaves. 
tuner_field_strength.patch
(4.8 KiB)
apps/lang/english.lang | 17 +++++++++++++++++ apps/lang/polski.lang | 19 ++++++++++++++++++- apps/recorder/radio.c | 16 ++++++++++++++++ firmware/drivers/tuner/lv24020lp.c | 4 ++++ firmware/drivers/tuner/tea5767.c | 4 ++++ firmware/export/lv24020lp.h | 1 + firmware/export/tea5767.h | 1 + firmware/export/tuner.h | 2 +- 8 files changed, 62 insertions(+), 2 deletions(-) |
This task depends upon
works fine on my x5,but poor TEA5767!
however this patch breaks the sim, so fix this.
* dropped the polish translation, it didn't sync properly anymore, and IMO we better do all translations at once
* fixed lv240x0 signal strength, I think the previous patch compared against the wrong values
Tested only on c200 which has a lv240x0 radio chip.
It looks like we're getting a "while-fm-screen" so this is a nice opportunity to revive this patch.
I'm thinking of having some kind of progressive icon that shows signal strength, similar to the volume icon (e.g. an antenna symbol with variable number of bars)
One thing I wonder about is in what unit the tuner driver should return the signal strength. Should we use dBuV like this patch, or maybe some kind of percentage?
What about LV240x0? Do you get a new value on a new signal strength register read?
As to the signal strength presentation form - if we would have antenna symbol with bars then it would be nice to display dBu value too. In the way two user groups would benefit. Those who aren't familiar with dBu units would be informed how strong is signal with easy to understand bars and those who are familiar with dBu would be given more detailed information about signal strength. Furthermore I think that unfamiliar ones would quickly learn correlation between dBu value and symbolic bar level.
The reason I asked about the unit is because I can imagine that different radio chips have different dBuV levels where they have "good" reception. I did have a look at the Si470x range of tuners and they also use 70 dBuV as maximum strength (it enables stereo at around 32 dBuV as far as I can tell), pretty similar to the LV240x0. Knowing this now, I think reporting the raw dBuV is fine.
Attached patch add support for the si470x tuner chips.
Attached patch syncs to current SVN, but still misses the updates to radio/radio.c to show the strength actually on the screen.