Scandata faq q12

4-Level FSK Data Decoder Interface Frequently Asked Questions File
By Bill Cheek

Before we proceed, it should be stressed that this FAQ is very old, and most if not all of the URLs and other contact information is gone. There are very few applications that would require a 4 level interface anymore that can't be handeled with another application. Project 25 decoding is now easily available and accessible (See our trunktrackers and decoders article). MDT decoding, though illegal, is almost impossible now with such data being encrypted anyway. This file is therefore presented as a legacy article and for information only.

Contents
=========

01: What do I have to do to get into 4-Level FSK decoding?
02: How do I go about getting into 4LFSK on my own?
03: What help is available for getting into 4LFSK decoding?


Questions and Answers

==========================================================
01: What do I have to do to get into 4-Level FSK decoding?

    The very first step is to install and test the NFM
    Discriminator tap or "Baseband Audio" Mod in your
    scanner using a 2-Level FSK Data Decoder Interface. This
    is a two-part process, fairly elementary, that is fully
    described in another of my FAQs called SCANDATA.FAQ,
    freely available at:

http://ourworld.compuserve.com/homepages/bcheek/scandata.txt

    So to answer your question specifically:

    A.  Install a "baseband audio tap" in your scanner, and
    B.  Build the simple 2-Level FSK Data Decoder Interface
    C.  Test it with a freeware program called TRUNKER, now
        in version 3.7 or so.

    After you've completed those first three steps, then:

    D.  Decide whether you want to have a go at the 4LFSKDDI
        completely on your own, or if you need varying degrees
        of outside assistance.

===============================================================
02: How do I go about getting into 4LFSK on my own?

    Cool!  That's the spirit!  Except this FAQ ain't the
    place.  There's not a lot to decoding 4LFSK signals,
    but you do have to have the right hardware and software.

    The software is a "no-brainer" for the most part,
    but you do have to build the 4LFSK Data Decoder
    Interface.  This puppy is just a little too "hairy"
    to put into a simple ASCII drawing like I did for the
    2LFSKDDI in my SCANDATA.FAQ file.

    So, you have to launch the adventure on your own, but I
    can help you get started.  Fire up your Web browser and
    check out the following sites:

    http://www.geocities.com/SiliconValley/Horizon/6063/

    http://www.qsl.net/pa3eik/4lev_fsk.htm

    http://www.geocities.com/CapeCanaveral/Launchpad/4039/

    http://www.geocities.com/ResearchTriangle/Lab/9339/

    http://www.geocities.com/SiliconValley/Network/8916/4levelm.gif

    Each of the above sites supports 4LFSK to some extent,
    be it hardware, software, or both.  If you are going to
    go it alone, on your own, then exit here and start
    researching those support sites.


==============================================================
03: What help is available for getting into 4LFSK decoding?

    First, no matter what, you should investigate the Web
    sites given in Q&A #2 above.  The information at those
    sites is helpful to some extent.  If you are technically
    inclined, those sites may be all you need or want in
    terms of help.

    If you are not technically inclined, or if those Web
    sites are so much "Greek" to you, leaving you with a
    feeling of helplessness.  Relax..............

    If you aren't comfortable taking on a 4-8 hour technical
    project on your own, or if you're a working stiff with
    spare time about as plentiful as gold, then maybe I can
    help to some extent.

    In fact, I can help in several ways, each designed for a
    specialized budget of time and resources.

    A.  I developed a detailed high-resolution laser printed
        Instruction Set that has 8-pages of text, tables,
        charts, drawings, references, parts lists and photos
        to guide the casual (or busy) hobbyist to success at
        decoding 4LFSK signals.

        If all you need is an A-to-Z guide that dispenses
        with technical jargon and just efficiently guides
        you from nowhere to success, then this Instruction
        Set might be all you need.  The price is right.

    4LFSKDDI Instruction Set; you provide all materials and
    parts, and build the hardware and set up the freely
    downloadable software per my guidance.

    Price:  $5, ppd USA.  $7, ppd, foreign
    ======================================

    B.  I can also provide a Kit of essential parts along
        with the Instruction Set in (3-A) above.  The Kit
        Parts List is given below along with other lists of
        probably needed or wanted materials that are not
        provided in the basic Kit.

    4LFSKDDI Instruction Set plus Kit of essential parts;
    you provide other optional materials and parts; build
    the hardware and set up the freely downloadable software
    per my guidance.

    Price:  $20 + $8 S&H USA.  $20 + $15 S&H, foreign

        Parts List (Stuff Provided in Kit)

        Qty    Description
        ===    ======================
         1     Instruction Set (See 03-A above)
         1     LM324 Quad Op-amp
         1     LM339 Quad Comparator
         3     capacitor; 2.2-uf/25v; tantalum
         1     capacitor; 0.01-uF/50v; monolithic
         2     capacitor; 0.1uF/50v; monolithic
         2     diode; 1N914/1N4148
         1     resistor; 1-M
         1     resistor; 2.2k
         2     resistor; 15k
         2     resistor; 100
         2     resistor; 22k
         2     resistor; 47k
         3     resistor; 2.7k
         1     RCA Jack
         1     DB9 Jack (female)
         1     Perfboard; 18 holes x 15 holes
         2     Trimmer pot; 10k; mini
                 or, at our option, two 4.7k fixed resistors

        Parts List (Probably needed or wanted; not supplied)

        Qty    Description
        ===    ======================
         1     Enclosure (Project box)
         3ft   Shielded audio cable (RCA plug on one end
                 with plug on other end to match the
                 baseband audio jack on the scanner.)
         6ft   Shielded serial cable  (DB9 female on one end
                 to mate to 4LFSKDDI output and a DB9 male
                 or DB25 male on the other end to mate to
                 the selected COMport on the PC.
         2     IC socket; 14 pin DIP
         ?     Small quan of 22-ga uninsulated solid copper wire
         ?     Small quan of 22-ga stranded, insulated,
                 color-coded hookup wires.
         ?     Small supply of "break apart" pinline sockets:
                 Digi-Key:  p/n A208-ND        (800) 344-4539
                 Hosfelt:   p/n 21-274         (800) 524-6464
                 Mouser:    p/n 151-5520/5530  (800) 346-6873
         ?     LEDs, switches, etc.
         1     Dual polarity power supply, +/-12.6 volts max
                 Can be as low as +/-5v, but 9 to 12v ideal.
                 Can be as simple as two 9v batteries or two
                 9v wall-warts wired as follows:

                 o----------> +9v on 4LFSKDDI Board
               + |
               -----
                ---   9v battery or
               -----  DC adapter
                ---
               -----
                ---
               _ |
                 o----------> Ground on 4LFSKDDI Board
               + |
               -----
                ---   9v battery or
               -----  DC adapter
                ---
               -----
                ---
               _ |
                 o----------> -9v on 4LFSKDDI Board


        OTHER NECESSITIES (Not provided)

        Qty    Description
        ===    ======================
         1     PC (Pentium 133+) (486 computers, maybe)
         1     Scanner with 800-960 MHz (cellular not required);
                 (must have NFM baseband audio mod)
         ?     Soldering equipment and basic electronic tools

    ================

     C.  I am working on ways to provide Assembled and Tested
         4LFSKDDI boards, including enclosures, power supplies
         and basically everything in a package.

         For now, all I can supply are prototype Assembled
         and Tested 4LFSKDDI boards with RCA and DB9 jacks
         attached....essentially ready for you to install in
         an enclosure of choice and connect the +/- power
         supply of choice.


     Price:  $100 + $8 S&H USA.  $100 + $ ? S&H, foreign

     NOTE:  This price includes only the Assembled/Tested
     4LFSKDDI board and jacks, as described above, as well as
     the Instruction Set. Power supply and enclosure not
     included.

     ================

     D.  Assembled/Tested 4LFSKDDI built into a suitable
         enclosure, with Instruction Set.  You provide the
         external +/- power supply.

     Price:  TBA (Not available yet) (or inquire for custom
             pricing)

     E.  Assembled/Tested 4LFSKDDI built into a suitable
         enclosure, with Instruction Set and power supply

     Price:  TBA (Not available yet) (or inquire for custom
             pricing)


OTHER INFORMATION
=================

     TO ORDER:  Use e-mail, fax, or postal mail per the
                information in my signature box below.
                MC/VISA or M.O. preferred. ($10 minimum
                credit card order) Personal and company
                checks okay, but shipment delayed until bank
                clearance. No COD's and no shipments to PO
                Boxes or mail drops. Alaska, Hawaii and
                foreign shipping extra. (Bill's old address is on the first page of the
                FAQ. No need to repeat it here, and he's dead anyway.....)

     TERMS:     All sales are final; no returns-no refunds.
                No warranty on Kits.

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