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The current 1999 SCANDATA.FAQ article (updatd by WJP in 2000) was originally produced by Bill Cheek of COMMtronics Engineering in 1996.

Bill Cheek was a scanner enthusist and author of several books and articles on the hobby. This article was a compilation of the various aspects of the scanner hobby dealing with discriminator output or baseband audio; explainting what it was, how to use it to decode a variety of signals, where to find it in a number of scanners of the day and also how to identify the various chips that it might appear on if your scanner was not listed.

It also explains the use of a and how to construct a 2-level FSK interface (data slicer) and a 4-level FSK interface. Note that some of the parts used and specified in the instructions may no longer be avaialable; however, these circuits have been updated several times and can be found with specifications of currently available parts in several places on the WWW including the Data Slicers article in this Wiki.


As this article, in its native text form, is a bit lenghty, we have broken it up into natural divisions so that it will more easily fit with the Wiki style of articles. Please note that we are leaving the text of the article intact in its entirety, but are dividing it up into logical sections. Also please note that the various URL's supplied in the article are probably not valid anymore as Bill Cheek died in 2000.



Mar 27, 1999       SCANDATA_faq       03/27/1999
Updated 09/23/2000   WJP

This article/file is for the benefit of all.

(c) 1999 (All Rights Reserved) by:
    Bill Cheek and -COMMtronics Engineering-

This file is for personal use only and may NOT be placed on
a CD-ROM nor any other media that conveys, stores, or
transports for any monetary cost including shipping &
handling, without expressed permission of the author. This
file can only be given away, absolutely free of charge, no
strings attached. If given away, it MUST be conveyed intact,
word-for-word with no editing, additions or deletions,
except as may be authorized in writing by the author.

                                   -Bill Cheek-

NOTE:  This Frequently-Asked-Questions (FAQ) file or article
       is one of a series of FAQs that I regularly publish.
       The complete list of FAQs is given below. If this one
       doesn't answer your questions, try one or more of the
       following additional FAQs:

1.  Scanner Modifications FAQ:  SCANMODS_faq
2.  Scanner Data Decoder FAQ:   SCANDATA_faq  <--- This FAQ
3.  Scanner Performance FAQ:    SCANPERF_faq
4.  Scanner S-Meter FAQ:        SCANSMTR_faq
5.  Scanner Radios FAQ:         SCANRADS_faq
6.  4-Level FSK Decoder FAQ:       4LFSK_faq
7.  Administrative FAQ:            ADMIN_faq

You can grab the latest of any of my FAQs directly from my
Web site as follows:

Questions and Answers

  • Q1: What is a 'Discriminator Output' and 'baseband audio'?
  • Q2: How can I find the Discriminator Output in my scanner?
  • Q3: How do I connect to the Discriminator Output?
  • Q4: How do I build or acquire a SIMPLE decoder interface?
  • Q5: How do I build or acquire a BETTER decoder interface?
  • Q6: So how do I decode digital data from the airwaves?
  • Q7: How can I decode CTCSS, DPL, and DTMF from the airwaves?
  • Q8: Is it possible to "TrunkTrack" without a TrunkTracker?
  • Q9: What if I don't want to build my own Data Decoder Interface?
  • Q10: Notice of Certain Data Decoder Limitations (and a fix!); an addendum published by Bill sometime after the original FAQ
  • Q11: What modifications to the interface might be needed to make it work with my radio?
  • Q12: Where can I find Bill's 4LFSK FAQ?


That's it for now.  I will keep this FAQ updated.  If you
see things that need to be added to it, by all means, let me
know. If this FAQ fails to address your question(s), then
hit me with 'em again, but be specific.  And be detailed
with symptoms and observations if you need tech support on
mods or troubleshooting and diagnosis.  Use e-mail.

Copyrighted (c) 1999 (All rights reserved) Revised 03/27/99

------------------------------------------------        --
Bill Cheek - President/CEO/Publisher            \      /
COMMtronics Engineering/World Scanner Report     \    /
Box 262478 ~ San Diego ~ CA ~ 92196-2478          \  /
Voice: 619-578-9247 (1:30-5:30pm, PST, weekdays    \/
  Fax: 619-578-9247 (any time)                     /\
E-mail:                           /  \ /      \
------------------------------------------------        --

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