Notice: This is NOT a "warez" site. You will NOT find any software such as radio and/or pager programming software here. I don't have RSS or similar software to send/trade or download. The software found on this page has been developed by others based on information available from public sources.

This page is for the advanced scanner user to determine what type of add ons can be added to a scanner to allow for various alerts etc..

It is taken that the user of this information has a background in the operation or radios, and an above average background in electronics. This information is not for the casual scanner user.

Most of the items listed here require connection to the discrimantor of the scanner to allow for proper or any operation. These include Digital ANI, Digital Paging, Digital PL/DCS, POCSAG/GOLAY/FLEX Paging. For accuracy PL & other tone formats should be connected to the discriminator, but you may find that for 5/6, 2, DTMF Tone decoding via the speaker/line out is workable.

Most of the products outlined here are commercial products meant to be used in the 2-way radio/paging industry for other purposes. Some of these items can be adapted to scanner use for those who need to decode alerts, monitor ANI of units etc.. Be warned that some of these items are priced substanially higher than hobbyist type accessories.

As an aid a chart has been included with each manufacturer to show what type of products they offer. To understand the abbreviations used refer to the following:

Scrambling Systems

There are various systems used to scramble radio communications. These include:

Analog Methods

Voice Inversion aka Voice Protection Accessory (VPA™)
Split Band Voice Inversion aka VSB™
Rolling Code Voice Inversion

Digital Methods

DES based Voice Encryption aka Digital Voice Protection (DVP™)

Voice Inversion is one of the most inexpensive methods available to secure communications from casual listening. Voice Inversion can be made into a medium level security system by employing systems such as Rolling Code & Split Band Inversion techniques.

The basic operation of the Voice Inversion system is a shifting of the low audio frequencies to the high frequencies, and the high frequencies to low frequencies, hence the name, as the frequencies are just inverted around a specified carrier frequency.

In an effort to make Voice Inversion more secure several firms offer different forms of Voice Inversion. These include Rolling Code where the inversion frequency is changed at random based on a seed code. Another is to split the voice band into two bands and then invert each band separately, or Split Band Voice Inversion. Another step to SBVI is to change the frequency of the split at random times, thus you get Variable Split Band Voice Inversion.

Voice Inversion is easily identified by its sound, similar to "Donald Duck". Rolling Code has a tick in the background to singal the scrmabling system to change the carrier frequency for the inversion process.

A way to identify the various modes is provided at ScanRite, which has WAV files of the various formats, inlcuding Voice Inversion & DVP.

The table below outlines the known inversion frequencies for most of the systems on the market today.

Carrier FrequencySystem(s)
3.339KHzMX-Com & Selectone
3.496KHzMotorola & Selectone
3.023KHzMX-Com & Selectone
2.729KHzTranscrypt & Selectone

Digital systems are far superior in providing secure communications. These systems take regular speach and turn it into a digital data stream which is encoded using one of billions of codes. Some systems provide for changing codes over the air, or even at random times.

The following firms offer scrambling systems:

4800 Bethania Station Rd.
Winston-Salem NC 27105
919-744-5054 FAX

Offers several forms of VI & VSBVI scrambling systems. Although from the web site it appears that the VSBVI line may have been dropped. All the VSBVI boards for radios are gone, and only the MX chip is listed, but no link to the product. Also offers chips to build scrambling systems.

Midian Electronics
2302 E 22 St.
Tucson AZ 85713-2024
602-884-0422 FAX

Offers lots of tone encoders and decoders, plus a line of VI & Rolling Code Scrambling systems. The VPU-2 product is tunable via a 15 turn trim pot to any of the available frequencies.

Transcrypt International
1620 N. 20th St.
Lincoln NE 68503
402-435-6780 FAX

Offers simple voice inversion scrambling, rolling code voice inversion & digital systems. Also offers some ANI systems, Options boards for Bendix-King Radios, and has produced its own line of Frequency Hopping radios.

12438 Loma Rica Dr.
Grass Valley CA 95945
916-477-8402 Tech.
916-477-8403 FAX

Offers a very nice add on VI scrambler, Model NC802, that will work with all the major brands, and includes a frequency not available on any other brand. Offers other tone signalling products as well.
3501 Breakwater Avenue
Hayward CA 94545
510-781-5454 FAX

Offers the ST-20 & ST-21 VI scrambler another very popular board for scrambling. Also offers DVP type models, and a line of tone products as well.
A software voice inversion product has also recently become available. For a copy of the software and more infomration contact the author at his website. Voice Inverter

Tony Rusho Email:

Requires a Full Duplex sound card and Windows '95.

Ramsey Electronics
793 Canning Parkway
Victor NY 14564
716-924-4555 FAX

Offers a kit & assembled VI scrambler, Model SS-70A, which is VPA compatible. Also offers a complete line of other hobby kits. These include a DTMF decoder, and DTMF display decoder.

CTP Descramblers
517 Lower Terrace
Huntington WV 25705
304-525-1761 Orders 24-hrs

Offers the Model DS-49 Voice Inversion descrambler. Comes in 3 models, kit form $39.95, Wired & Tested $59.95, and W & T w/external controls $79.95.

This kit is the only product that claims to offer the ability to decode VSBVI!

Tone Decoders

Having a scaner like the BC760XLT, RS2035 w/OS535, or HS-200 which can decode PL or DPL is great way to reduce listening to interference & units your not interested in, but how do you find the PL or DPL in use!

You need a tone/code decoder which will display the PL or DPL being used.

The best source ot these is:

Connect Systems Inc.
2259 Portola Rd.
Ventura CA 93003
805-642-7271 FAX

Offers the CD-2 which will decode and display on LED readout the PL, DPL, or DTMF received on a channel. Also connects to an RS-232 port to log tones to a file.

Another source of tone decoders is:

Optoelectronics Inc. 5821 NE 14th Ave.
Ft. Lauderdale FL 33334
954-771-2052 FAX

Offers the DC442 Tone Decoder which will decode and display PL, DPL, & DTMF tones. Can be connected to RS-232 & CI-V ports.

Also offers the Xplorer test receiver which will also decode & display PL, DLP, & DTMF tones. Can be connected to RS-232, CI-V, & GPS NEMA-0183 interfaces. Also serves as a near field test receiver displaying frequency as well as tones.

See also Universial Radio M-450, below.

Software which will decode DTMF and PL tones has recently been developed. This software uses a SoundBlaster compatible sound card to decode DTMF and PL tones in real time.

Download the software

Author: Emil Laurentiu Email:

Requires: 386 or better, VGA, Sound Card

A second program to decode DTMF, PL, 5/6 Tone ANI is WinTone.

Requires: 586, Sound Card, Windows 95

Paging Decoders

Did you ever wish you could get alerted when the local FD, EMS or similar Public Safety agency gets an emergency call?

If you can dedicate an older scanner to monitoring that agencies channel you can add on a paging decoder to decode the normal 1+1/2 Tone Sequential paging used by most of these agencies.

Communications Specialists
426 W Taft Ave
Orange CA 92665-4296
800-850-0547 FAX
714-974-3420 FAX

Offers the SD-1000 1+1/2 Tone Sequential paging decoder which can set up for any of the standard Motorola & GE tones, or programmed with 32 tones of your choose. The SD-1000 is sold to decode groups like Motorola Groups 1 to 3, GE ABC, Motorola ABZ etc.. If you want to use the decoder to be able to decode different calls which span series of tone groups then get the unit programmed for your choice of 32 tones. The SD-1000 can also encode a PL tone.

You can connect the decoder to activate the speaker in the scanner, activate a light or siren, or whatever you want to alert you of a call.

You need to know the tones & format used to activate the agencies pagers. This information is not given out to the general public. You could record them and use some test equipment to determine the tone frequencies. Using a simple stopwatch can give you the tone times, if your quick. You may need to use some test equipment to determine the timing as well. Compare the times with the formats listed on the Tone & Signalling page to determine the format. You may also be able to do this by ear.

Bramco Inc.
9676 N Looney Rd
PO BOX 1482
Piqua OH 45356-1482
513-774-8003 FAX

Offers a full line of DTMF ANI products, along with 1+1 & 2+2 encoders/decoders. Model 2764 1+1 & Model 2962 2+2 decoders are available. Also offers replacement reeds for Motorola Minitor I & II™ pager monitors.

Genave / NRC, Inc.
1120 220th Street West
Farmington, MN 55024
612-460-6686 FAX

Offers the Page Logger which will decode 2 Tone formats & DTMF format paging and sends this data to the serial port of a computer. The unit can determine the formats used by the source, take action on pages, and alert users via the computer of selected pages. Cost $485.00

See also Midian, above, for similar 1+1/2 Tone Sequential Decoders.
Also available are Pager Tone boards from Denis Dandeneau K1STB.
Denis Dandeneau K1STB
P.O. Box 7052
Warwick, RI 02887-7052

Here is the information I received:

Boards are 74.95 tuned to the tones supplied. User must hook it up.

25.00 for hooking into scanner and making it a tone alert / monitor radio

15.00 for 3 second alert or single gong bell can be added in place of aert tone

65.00 for 10 inch red single stroke fire house bell

25.00 for circuit to turn lamp on after tones are received




ANI Decoders & Displays

Decoding of ANI on any channel will be very random unless you can dedicate the scanner to the task, and for digital ANI such as GE-STAR™ et al you will need a discrimator connection.

For DTMF ANI there are several kits & ready made devices available to decode DTMF ANI. (See Bramco, Ramsey, & software DTMF decoders.)

Most digital decoders will be outside the price range of the hobbyist, $600.00+ for a basic unit

5/6 Tone/Modat/CCIR/ZVIE/ZZVIE Tone ANI

Software to decode this format is available from this web page. All the documentation and screen displays are in Dutch at this time.

For additional 5/6 Tone format ANI decoders, see WinTone, below.

Paging Decoders/Logging - Digital & Tone Formats

This section is provided for those person(s) covered by 18 U.S.C. 2512(2) to use such devices. By accessing this page you agree that you are permitted to use such devices under 18 U.S.C. 2512(2) to receive these broadcasts. This is NOT an advertisement of device a for sell for any device(s) listed.

Ever wish you could verify that your pages are sent?

Now you can with some simple software/hardware for a compter or a dedicated device.
Hark Systems

Markets "The Verifier" which is a stand alone decoder for 5/6, 2 Tone, GOLAY & POCSAG paging protocols. Ouputs to a serial (RS-232) and parallel printer port for logging. Cost $1,500.00.

Several software/hardware solutions to POCSAG pager logging have been developed. Some of these even allow for the user to send POCSAG pages to a local transmitter.These inlcude:

PD- POCSAG Decoder

Uses an external interface and software to decode 512-2400bps POCSAG data.

Accupage RM100 - Is an external interface and software that allows you to decode & log POCSAG pages. Can also take action on selected capcodes. This is the software/hardare from the March 1997 Popular Electronics article.

Requires: Windows 95, External Interface

Cost: $60.00 for complete kit for interface and software.

Cylex Inc.
Tech Support:281-554-8833

SemaSoft - Uses a sound card to decode 512bps POCSAG only. Author is looking into 1200/2400bps support along with DTMF decoding. The latest version at the time of creation for this page (4/97) is V1.15

Requires: Windows 95 and Sound Card

Author: Rene Hagen Email:

POC32 - Pager Monitor and Encoder

Using a sound card or an external interface you can monitor upto 3 channels of POCSAG input, and send POCSAG pages to a local transmitter.

Author: Deti Fliegl
Another POCSAG decoder is available from Bernard Galasso.

New (6/15/97) software to decode 512 to 2400 baud POCSAG. Get a copy here.

Requires: HAMCOM type interface, per documentation.


Program decodes, POCSAG, GOLAY (GSC) & Flex protocols.

Trunking Decoders

With the recent debut of the Uniden/Bearcat BC235XLT scanner, one firms, Motorola, form of trunking is now easily followed by scanner users. That still leaves GE/Ericsson & E.F.Johnson/Uniden/Standard LTR trunking systems not as easily monotired.

For LTR trunking systems, if the system is not busy you will notice that the users will stay on their "home repeaters" similar to a convetional repeater most of the time. Once the system activity picks up and channels are in use with multiple groups etc. normal trunking will start.

One way to possibly ease LTR monitoring is the LT-2 LTR Trunking decoder from Connect Systems. This device displays all the various data needed to monitor an LTR system. With the approriate software and a LT-2 connected to a computer & a computer controlled scanner an LTR system could easily be followed. At this time no software to take the LT-2 data and control a scanner exists.

New TRUNKER INFO HERRE DL Site: Recently on source code for decoding the Motorola Control Channel data was posted. With this software, and a comptuer controlled scanner one could follow a Motorola trunking system. With the release of the Uniden/Bearcat BC-235XLT Trunk Tracker the utility of the software may or may not be present. I leave that for you to decide.

The archive contains the executable for those without C compilers. This was compiled by a very generous person.

NOTE: I am NOT the author of the code, or compiler of the code. I am simply making these available for download here.

Download the Control Channel Software V2.0. (Original Version, Updated 2/17/97)

I have recently received a NEW version of this software with MANY enahncements. Please check out TRUNKER.EXE V3.x here.

Treport Info
For those attempting to monitor GE-EDACS type systems some software has recently been released to allow for scanner users to follow this system.

Download EDACS Software

Another problem with GE-EDACS systems is the annoying tones present as "scanner eliminators". Some software has recently become available that will allow a BC895 scanner along with and IBM PC eliminate the tones.

GE-Ease Home Page

GE-EASE Sofware

Contact GE-EASE Author Aaron Rossetto

MDT Decoders

Recently sofware to display unencrypted MDT transmissions using Motorola MDT-4800™ format has become available. This was posted on, and was compiled by a generous person. I am making this available for your testing. The ZIP file contains the compiled executable, along with the source code if you desire to make changes.

The software does not work on systems which encrypt the tranmistted data, nor does it work on any system other than the MDT-4800.

NOTE: I am NOT the author of the code, or compiler of the code. I am simply making these available for download here.

Download the MDT software.

MDT Monitor for Windows is another program to monitor MDT data with either a sound card or the data interface used by the CyLex RM-100 Pager Monitor..

Mobitex Decoders

Also recently posted to UseNet was software which allows you to display the transmissions from an unencrypted Mobitex system.

NOTE: I am NOT the author of the code, or compiler of the code. I am simply making these available for download here.

The archive is available here, and includes source code.

Interface Circuits

Most of the software for the POCSAG/MDT/Mobitex/Trunker programs needs an interface to get the signal to the computer. Almost all of these software programs use the simple op-amp based circuit orginated in the PD software.

Optoelectronics Optolinx interface for computer control also offers a Data Interface for use with PD, POC, KRACARS, etc..

On UseNet a discussion on how to improve these circuits. These included many tips which could mean the difference of not getting the software to run, and getting error free or useable results.

Below is the posts from UseNet, unedited.
On 11 Apr 1997 16:30:43 GMT,
in the newsgroup, (Bich Tran) 
from Hewlett Packard thoughtfully posted:

> Boy, I received so many email regarding my future mdt-hacked program.
> Some reported failure to make circuit work. Here are some of the pitfalls
> you should watch out when building the MDT ckt, ( this is my experience only):
> 1. The +/-12V generator subckt is marginal. If the opamp is drawing too
> much current, the -12V line will be overloaded and drops to almost 0 volt!
> Enough to stop the ckt from working.

The LM741 draws about 1.5mA, and the serial port should be able
to source at least 10mA. Some laptop serial ports may not be able
to source much current. Use as large of supply filter capacitors
as possible to prevent "sagging". 

Make sure you are using 1N4001/2/3/4, 1N914 or 1N4148 diodes.

The circuit, as given in the original documentation, *will* work.
However, some have reported difficulties. Excluding wiring
errors, I think this may be a signal level/discriminator loading
problem. If you are having problems, please post which circuit
you are using and the type of radio used. I bet we will find some

> SOLUTION: use a small dual DC/DC converter, such as the BurrBorwn PWR1205
> to convert a 5V to +/-12V. Of course a drawback of this approach is an
> external 5V power supply.

If you have access to these, why not just use a low-supply
current part? Like an OP-21? LF441? (Careful, some micropower
parts are only good up to +/-8V).

> 2. If you are using a cable extender to connect your ckt to your computer, like
> my does), beware of the object/mirror phenomenon. So pin 5 (ground) should
> be pin 1 on the mating connector, etc... The pin number listed on the
> schematic is only the pin on computer side, so to be on the safe side use
> a continuity checker to trace the signal line before soldering the connection.

True. And also watch long cable lengths. Some op-amps cannot
drive high capacitive loads, and will self-oscillate. If you find
yours is oscillating, place a 100 ohm resistor between the output
and the cable.

> 3. Any dual power opamp will work: I both successfully use a TL072, and a
> comparator LM393.

I recommend the use of JFET input type op-amps
(TL071,TL081,LF411,LF351,etc). The input impedance is 10X higher,
and the input bias current 10x lower than the 741. With the
higher input impedance, you can increase the size of the
resistors 10 times (ie:10K=100K, 100K=1Meg, etc), thus reducing
the loading of the discriminator circuitry.

For various reasons, an isolation resistor and the input
capacitor should be mounted *inside* the radio. Bringing the
discriminator output directly to the outside is not recommended
(RFI, danger of shorting, etc). I recommend you connect a
isolation resistor and cap in this fashion:

		      C1     connecting wire
Tap point--10Kohm----0.1uF-------------------rear panel jack<

If you use a shielded connecting wire, ground the shield at the
panel. C1 is the input cap of the "interface".

radio, may not work on another. A minimum of 20-50mV p-p is
required for a good "copy".

Recommended Circuit: The "Schmidt Trigger circuit"

This is the circuit for *JFET* type op-amps!!! NOT 741's!!

  C1(mount inside radio)
  0.01 uF                    |\ +12v
---||----O------------------|- \|
AF IN    |                  |LF \	 R4 (opt)
----     |                  |411/-O---/\/\/\------ Data Out
    |    \  R1        ------|+ /|  |     100       CTS (pin 5/8)
    |    / 1Mohm      |     |/-12v |
    |    \            |     R2     |    GND ------ GND (pin 7/5)
   GND   /            O---/\/\/\---- 
         |            |    1Meg 
	 |	      |
         |            \        N.B. Pin Numbers for com port are
        GND           /  R3    given as x/y, where x is for a 25
                      \  10K                  way, y for a 9 way.
                      |  Op amp is a TL071,TL081,LF411,LF351,etc

R3 determines the hysteresis level (determined by ratio of
R2/R3). R4 is optional, use if driving long cables. Note that C1
is smaller, too.

Simpler circuit:

  0.01 uF                    |\ +12v
---||----x------------------|- \|
AF IN    |                  |LF  \	R2 (opt)
----     |                  |411 /-x---/\/\/\------ Data Out
    |    \  R1        ------|+ /|        100       CTS (pin 5/8)
    |    / 1Mohm      |     |/-12v  
    |    \            |                 GND ------ GND (pin 7/5)
   GND   /            x
         |            |    
         |            |       N.B. Pin Numbers for com port are
        GND           |        given as x/y, where x is for a 25
                      |                       way, y for a 9 way.
                      |  Op amp is a TL071,TL081,LF411,LM351,etc

This circuit is more sensitive to noise, and should only be used
on strong signals.    

An oscilloscope is invaluable in troubleshooting these circuits.
If you have access to one, use it!

> Please advice me how to post the binary file, since I don't want to offend
> those sensitive souls who dislike seeing binary files posted in the newsgroup

Don't! You will probably be contacted by folks willing to place
it on a FTP site for you.

Good Luck!

Paul Grohe

 Paul Grohe                     National Semiconductor Corp.
 Sr. Electronics Technician     2900 Semiconductor Drive
 Standard Products Apps Group 	Mail Stop C2693           Santa Clara, CA. 95052-8090 USA
 (408) 721-7389 Tel             (408) 721-2513 Fax 


I've recently gotten interested in the ACARS aviation data format due to some very interesting software on the net. This includes javAPRS which allows you to display all types of live data on an APRS map. An example is some live ACARS data for the area around the U.S. Naval Academy, to see it click here.(Requires: Java)

Look for some more ACARS resources here shortly.

To decode ACARS requires some hardware and software, or a standalone decoder. The Universal M-400, M-450, & M-1200 decoders can do this. Many Amateur radio TNC's can do this too. There also exists many external ACARS only decoders. I've recently found a software only version which uses a PC and sound card.


KRACARS.EXE is an ACARS decoder for the PC which attempts to decode ACARS transmissions in real-time using a Sound Blaster Pro or Sound Blaster 16 (or compatible) soundcard.

This early version of KRACARS has been released for beta testing. Although there is no warranty provided with KRACARS, I would welcome any comments, problem reports and other feedback you may have concerning this software.

1. PC with at least 1Mbyte RAM, minimum CPU requirement unknown,
2. DOS, minimum version unknown,
3. SoundBlaster PRO or SoundBlaster 16 (or compatibles),
4. Radio receiver with audio cable for connection to soundcard,

You can contact me by email
Download KRACARS ACARS software.


Sofware for the PowerPC MAC will decode ACARS, RTTY, FAX, and even WWVB time signals!

Download Multimode for the PowerPC MAC


WACARS - ACARS Reception and Decoding Software For Windows

Is another software only ACARS decoder for use under Windows.

IBM PC w/WIN3.1 or WIN95
Sound Card which support 19.2KB/sec. sampling rate

Download WACARS here. Database to use w/WACARS, download this too.


Recording Software

Scanner Recorder
Computer: 486+/4 MB RAM/770K program, not including audio storage use. Operating System: Windows 95/ Windows NT. Hardware: Windows compatible sound card that has record capability, only 8 bit samples supported currently.


Requirements: 486DX33+Windows 95 or Windows NT 4.0 or Windows(tm)3.1, sound card with Wav support, 1meg disk space, 486DX33 or faster, microphone. Automatic gain control recommended.

Record your scanner on your computer for later playback. Both programs support Voice Operated Modes (VOX), to conserve disk space.

Notice: This is NOT a "warez" site. You will NOT find any software such as radio and/or pager programming software here. I don't have RSS or similar software to send/trade or download. The software found on this page has been developed by others based on information available from public sources.

Warning: This page contains information which if used improperly will violate Federal Law. This information is presented for persons to monitor communications for which they are a party to and/or authorized to receive. These options may also require the performance of modifications to circuitry of your scanner, and should only be performed by qualified persons. The author of this page makes no warranty to the use of this information which may result in damage to your scanner. Use at your own risk!

Copyright © 1994 - 2000 R.E. Christian, All Rights Reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, electrical, chemical, optical, mechanical, photocopying, recording or otherwise without the prior written permission of the copyright owner. All trademarks property of respective companies.
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