Questions about FM/ AM tuning intervals

[Limpid]

I’ve some basic question about the AF / FM tuning intervals across regions. In US FM frequency spectrum is 87.9Mhz -107.9 MHz with interval of 200KHz. In India I think its 87.9-108MHz with interval of 100Khz (?). But strangely almost all the private Indian FM channels are spaced on odd frequencies. Like radio mirchi 98.3, Radio city 91.1MHz with some exceptions. AIR channels are on even channels. In fact Radio city changed their frequency from 91MHz to 91.1 MHz couple of years ago. Does anyone knows why? And why are they broadcasting on odd frequencies?
Reason I am asking is many people buy HUs from abroad and they should work fine on these FM channels most of the time (do they?)
What about AM does anyone knows how AM’s frequency distribution across the regions is?
I also would know to know if any HU provides 'fine tuning' option ?

[DerAlte]

Originally Posted by Limpid

In US FM frequency spectrum is 87.9Mhz -107.9 MHz with interval of 200KHz. In India I think its 87.9-108MHz with interval of 100Khz (?). But strangely almost all the private Indian FM channels are spaced on odd frequencies. ...

The fact that most Indian channels are at odd frequencies is a matter of simple choice - the radio "monitors" can figure from the frequency whether this is a private or govt. controlled station.

Originally Posted by Limpid

Reason I am asking is many people buy HUs from abroad and they should work fine on these FM channels most of the time (do they?)

Sure they do, once they are tuned. The problem is the "auto-scan", which skips 200KHz in US and 100KHz in others (not sure about Japan, where the system is again slightly different). If manually set, you can select the exact frequency in either.

Originally Posted by Limpid

What about AM does anyone knows how AM’s frequency distribution across the regions is?

AFAIK 9-10 Khz apart.

Originally Posted by Limpid

I also would know to know if any HU provides 'fine tuning' option ?

Almost all do. My 2000 vintage Kenwood (forgot the model, a cassette deck with CD changer) had suffered from "drift", which was correctable: Radio City would come on at 91.05MHz!

[condor]

Limpid : But strangely almost all the private Indian FM channels are spaced on odd frequencies. Like radio mirchi 98.3, Radio city 91.1MHz with some exceptions. AIR channels are on even channels. In fact Radio city changed their frequency from 91MHz to 91.1 MHz couple of years ago. Does anyone knows why?

Have you noticed the frequencies of the stations in BLR ?
91.1, 91.9, & 93.5, 94.3 etc . There is a spacing of 800 KHz used in India (at least in BLR). Just list out all the stations we have in BLR, and you will see this pattern. (Sorry, but dont remember the other frequencies).

The change of frequency done by Radio City was to follow the 800 KHz spacing directive.

Limpid : Reason I am asking is many people buy HUs from abroad and they should work fine on these FM channels most of the time (do they?)

You can select a suitable step value to be able to tune in better. My Alpine (purchased here) has two zones options. Both have a different step level - just had to switch the zone to get it to work correctly for use in BLR.

[navin]

see post 12
http://www.team-bhp.com/forum/ask-gu...html#post84445 (Mp3 unit query)

and links in post 16
http://www.team-bhp.com/forum/ask-gu...tml#post117766 (want to buy a good car audio system)