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Caller ID chips

Discussion in 'Electronic Design' started by Spehro Pefhany, Oct 26, 2004.

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  1. Are there any good options out there other than Holtek and Mitel?
    Preferably more available than those two.

    Either a caller ID chip with a MCU interface or a Flash or OTP MCU
    with FSK capability.


    Best regards,
    Spehro Pefhany
  2. Jim Thompson

    Jim Thompson Guest

    What are you needing to do? I'm about to resurrect some of my
    _ancient_ analog designs to do call screening. At least I know I can
    get the parts ;-)

    ...Jim Thompson
  3. rwiehler

    rwiehler Guest

    I used to use the MC145447. is it still available?
  4. Hi, Jim:-

    I just want to throw a quickie special stand-alone call display
    together for my own use, so the modem bit would be the same as your
    application. It might become a product later.

    Best regards,
    Spehro Pefhany
  5. Paul Burke

    Paul Burke Guest

    I've been looking too. I ended up advising the customer to buy a few
    hundred of the Zarlink (ex Mitel) parts, that would see him over the
    next 6 months or so while we sort something out. Even they were
    available only in the SM version. There's a Texas appnote on DTMF
    detection using the MSP430 but you'd have to watch the dynamic range.

    Paul Burke

    Paul Burke
  6. Jim Thompson

    Jim Thompson Guest

    Hi Spehro,

    See my patent, 4,472,816, FSK Discriminator, purely analog, marvelous
    noise rejection, unlike all the timer-type chips.

    Some lurkers will recognize my gyrator filter in there ;-)

    It's the scheme I used (in the mid '70s) to do modems for the
    OmniComp/GenRad portable testers. I used to test the scheme, over
    ordinary phone lines, from Phoenix to Louisville, thru an acoustic
    coupler, and back to Phoenix, with very good error rate.

    ...Jim Thompson
  7. Rolavine

    Rolavine Guest

    From: Paul Burke
    Caller ID is sent FSK and not DTMF. I helped develop mdifications to AT&T Slic
    systems and cards so they could do caller ID when it was first developed. I
    think the tones were 1200 and 2250 hz. but this takes me years back. My memory
    is that it used the tones of 300 baud fsk but operated at 1200 baud. Current
    processors are fast enough and low power enough to do FFTs looking for these
    frequencies and extract the calling number. The unit only needs to run for a
    second after the first couple of rings. I'm sure I could do this with a PIC.

  8. Jim Thompson

    Jim Thompson Guest

    Haven't tried it at 1200/2200, but I'll think on it ;-)

    ...Jim Thompson
  9. Nice. It certainly looks straightforward. Do you think it would work
    well on caller ID signals- 1200/2200 Hz at 1200 baud? There's only one
    full cycle of 1200 Hz and less than two of 2200 Hz per bit time.

    Best regards,
    Spehro Pefhany
  10. I'm just looking at the API for a dsPIC 1200 baud soft modem. The
    analog stuff would be cheaper and maybe faster to develop. It uses
    around 5 MIPS, with the core routines written in assembler, on a
    16-bit machine with a 17 x 17 high speed multiplier and MAC.

    Best regards,
    Spehro Pefhany
  11. Tim Wescott

    Tim Wescott Guest

    I've coded a 400-baud modem on an 8-bit processor that runs about 1/2
    MIP, without using the multiply instruction (on a 68HC11). Ran about
    1/2dB below the theoretical best BER for the format.

    Perhaps Microchip didn't do the best possible job with their code?
  12. 1) They have 30 MIPS to play with.

    2) The programmer's name is Ravi. It was reviewed by Raghava.
    (it was outsourced-- "Third-Party Developer", so they may well
    have not bothered with optimization- but they damn well got
    the hyphenation right)

    Best regards,
    Spehro Pefhany
  13. Tim Shoppa

    Tim Shoppa Guest

    Ughhh... no need to do FFT's! Just convolute the signal with the two FSK
    frequencies and their conjugates, sum the squares to find the energy
    at each frequency and discriminate!

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