Help needed: FM tuner configuration values

[bluebrother]

Currently the FM tuner is restricted to frequencies between 88 and 108 MHz with a step size of 0.1 MHz. Also the deemphasis is fixed at 50µs. While this applies good to europe it isn't a good solution for other countries like the US. After some discussion (see http://www.rockbox.org/tracker/task/5929) I started working on a patch which sets these values depending on the location. Unfortunately I wasn't able gathering all required data.

The data currently available is like this:

#	Location	Frequency range (MHz)	Step size (MHz)	Deemphasis (µs)
1	Europe	87.5 - 108.0	0.05	50
2	US & Canada	87.9 - 107.9	0.2	75
3	GB / Ireland	same as europe
4	Japan	76.0 - 91.0	?	?
5	China	98.0 - 108.0	?	?
6	Korea	87.5 - 108.0	0.1	?

• OIRT: not possible with the TEA tuner (iriver, some archos) as it can tune down only to 76 MHz
• US Weather: the same, TEA can only tune up to 108 MHz
• The Samsung tuner can actually tune to these frequencies, but I think it is better to have the same settings on all players
• Japanese TV: should we really add this as separate setting? How frequently is this used for audio only reception? If someone actually wants to receive that he can always use the europe setting ...

Please post your local settings, I'll try to keep this table up to date from the values posted. Also, if there are errors in the above table please note that.

Thanks!

[AlexP]

Hi,

The UK is 0.05 MHz step size, and has a range of 87.5 - 108 MHz.  I'm pretty sure the de-emphasis is 50 us also.

We are the same as Europe (we are in Europe!   as I imagine this is an EU standard.

[tucoz]

According to the TEA reference manual, the FM frequency range in Japan is 76.0 MHz - 91.0 MHz.

[HorstIriver]

Bluebrother, I would go with the narrowest step size (0.05MHz) for all regions. Not only will it simplify the region setting code, but it will also improve the reception if you want to receive a weak station close to a strong station. At analogue receivers, you can slightly mistune the weak station, away from the strong one, to reduce the splatter at the expense of reduced stereo channel separation. So the finer the tuning steps, the better. Switching the frequency range and deemphasis, depending on the region, would be good enough.

[pabouk]

I can confirm the frequency ranges.

There are two additional ones:
– East Europe FM  65.8 to 74 MHz  with step 0.01 MHz (OIRT)
– US weather        162.4 to 162.55 MHz

Eastern european range is used probably in a few countries now:
Russia, Belarus, Moldova, Hungary, (? Armenia)
http://en.wikipedia.org/wiki/FM_band#OIRT_bandplan.

More infromation from Wikipedia:
http://en.wikipedia.org/wiki/FM_band
- Japanese TV audio  90-108 MHz
- 0.05 MHz step is used only in some european countries (Italy)
but as HorstIriver said it is useful to have fine tuning anyway.

It would be useful if the parameters (frequency range, step, de-emphasis) could be set individualy or by selecting a preset like Europe, USA, Japan etc.

[HorstIriver]

Pabouk, for technically informed people individual settings of the parameters is fine. But many users don't know anything about those details, they only know what region they live in. It requires some comments in the manual about the correct parameters for each region.

[Llorean]

It could be done very much like the "EQ" screen where you can load presets, or set it yourself. And then we could simply include the presets in the main download.

[NuJew]

Thailand   87.0 - 108.0   

0.05 for urban area
0.25 for city area

[dunno]

on the main FM wps screen expand the following two menus , Auto scanning or Manual scanning.

Auto scanning:
include under Auto scan a field for country, defaults are then loaded for that country and auto scanning proceeds as per normal.

Manual scanning:
have fields for the following
i). Country (automatically loads all defaults for fields below).
ii). frequency Range ?(perhaps this should be preset and non user adjustable)
iii). Frequency Tunning increments.
iv). Emphasis.

one should then be able to initiate an auto scan with values entered into fields manually.
Also perhaps have a method to store manual scan settings, (like EQ settings are saved).

my .02c worth