[maemo-developers] FM RDS data

[From: Aldon Hynes]

You should take a quick look at the fmtx_client command.  It already does much of what you want (with the exception of finding an unused signal)

fmtx_client -f sets the frequency
fmtx_client -s sets the radio station
Note:  This must be an eight character string, but it can be padded with blanks.  This is a bug that has been fixed in the next flash
e.g. 
fmtx_client -s aldon   
will not work but
fmtx_client -s "aldon   "  
does work

fmtx_client -t sets the text.  This can be any length and can have embedded blanks
e.g.
fmtx)client -t "This is a long test"
works.

I've used this to send messages from my N900 to the RDS display on my car radio and it has worked nicely.  (and members of the family have enjoyed receiving personalized messages on the car radio)

Aldon
  -----Original Message-----
  From: khertan at gmail.com [mailto:khertan at gmail.com]On Behalf Of Benoît HERVIER
  Sent: Thursday, January 07, 2010 12:19 AM
  To: Martin Grimme
  Cc: Aldon Hynes; maemo-developers at maemo.org
  Subject: Re: FM RDS data


  About FM and RDS modifying RDS signal transmited from the tablet is possible ?

  I'm thinking of a small usage, a app that found the freest frequency (by listening fm with the transmitter) and change the frequency of transmitted music to the found one and send an rds signal by the transmitter, so you don't have to change frequency on your car receiver (or everything else).

  I know that fm transmitter emit an rds signal ... but can that be changed ?

  Does there is documentation about the fm transmitter and receiver somewhere on Maemo ?

  Thanks a lot


  2010/1/6 Martin Grimme <martin.grimme at gmail.com>

    Hi,

    the FM receiver's interface for RDS is exposed via sysfs. So any
    application can read RDS data from it.
    The frequency bands the receiver is capable of are US/EUR (87.5 -
    108.00 MHz) and Japan (don't remeber, but I think starts somewhere at
    70 MHz). A region switch in the driver (sysfs-Interface again but as
    root) switches between the frequency bands.


    Martin


    2010/1/6, Aldon Hynes <Aldon.Hynes at orient-lodge.com>:

    > I have been approached by a person interested in sending data from a sensor
    > via FM to a cellphone which would in term transmit this data to the
    > Internet.  I am interested in figuring out if this is something that could
    > be done with an N900.  With that, I have a few specific questions:
    >
    > First, can anyone point me to information about how to programatically
    > receive RDS data?  I've read that the FM receive app is supposed to do that,
    > but I haven't managed to receive RDS data that way yet, and I don't have the
    > source code.
    >
    > Second, does anyone have any idea what frequencies the FM receiver can tune
    > into?  The programs I've seen have focused on the traditional commercial FM
    > band, 88 Mhz to 106 Mhz.  Can the FM receiver tune in higher or lower
    > frequencies?  If so, what is the real frequency range of the FM Receiver.
    >
    > Third, are there other data formats that can easily be sent and/or received
    > from the Nokia phone?  If so, can people point me to any of these other data
    > formats?
    >
    > Any help you can provide would be greatly appreciated.
    >
    > Aldon
    >
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    >
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  -- 
  Benoît HERVIER - http://khertan.net/


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