• How do I connect my scanner to the computer so I can decode MDT data?
• Nothing happens when I run the program, what's wrong?
• Where should I look for MDT frequencies?
• Where can I get a HamComm-type data slicer?
• Where can I get an RM100 decoder?

Questions about the program

• How can I stop the MDT window from updating so I can read it?
• How do I enter aliases for the terminal numbers?
• How can I change the size of the Messages, Active Terminals, and MDT windows?
• Nothing ever appears in the top window, why is this?
• What are rules and how do I set them up?
• I monitor more than one system, how can I keep my settings separate?

Support for other interfaces/protocols/operating systems

• Do you plan on adding support to monitor systems which use the RD-LAP protocol?
• Do you plan on making a version of the program available that runs on Windows 3.1?

How do I connect my scanner to the computer so I can decode MDT data?

To use MDT Monitor (and most other programs that decode data received by the scanner) you need a scanner with a discriminator output. Chances are your scanner does not have one of these outputs (most do not). If your scanner doesn't you'll need to take it apart and add one. Bill Cheek has written some very good instructions on how to make the modification required.

At this time you can connect the discriminator output to the computer using three methods:

• You can plug the output into the microphone or line-in input of your sound card to decode the audio. This method produces the best results if your sound card samples at exactly the rate requested by the program. Not all sound cards will work, some aren't very precise in their sampling of the audio data (there's more on this in the answer to the next question).
• You can plug the discriminator output into a decoder made by Cylex, Inc. and then plug the decoder into one of your PC's serial ports. If you're receiving some static this method won't work quite as well as the sound card method but is still very good. This method (and the one below) should work for everyone whether the sound card method works for you or not since the sampling of the audio is taking place in the decoder instead of in the computer.
• You can plug the discriminator output into a HamComm-type data slicer (under Windows 95/98 only) and then plug the data slicer into one of your PC's serial ports. Unless you have a perfect signal with absolutely no static you'll see more errors using this method than when using the sound card or an RM100 decoder to decode the data. This is because the program isn't able to recognize and ignore noise in the signal.

Nothing happens when I run the program, what's wrong?

The program will only work with the discriminator output from the scanner, you can't use the audio from the earphone connector.

If you're using the disciminator output and have it connected to your sound card try the following:

• Try reversing the polarity to see if that does any good. Do this by opening the View menu, then choose Options and then select the "Data Source" tab. Click in the "Reverse Polarity" checkbox in the "Sound Card Settings" part of the window to reverse the polarity. If you move the discriminator connection from the mic-in to the line-in input (or the other way around) you may need to change this setting.
• Maybe the program isn't seeing the audio from your scanner, to see if it is open the View menu, then select Analyze Signal. You should see something that resembles a square wave. If you don't there might be something wrong with the connections. Check to see if the Windows Sound Recorder (in Accessories) sees the audio by using it to record a sample.
• Try changing the recording volume of the microphone/line-in input (whichever you're using), if the volume is set to high the audio will become garbled and unintelligable to the program, if it's set to low the program may have trouble "hearing" the signal. Also make sure Windows is setup to listen to the input to which you connected the scanner. To check or change these settings double-click on the speaker symbol in the system tray, then choose Properties from the Options menu, then select Recording in the "Adjust volume for" part of the window. Make sure the Microphone/Line-in checkboxes are checked in the bottom part of the window, then click on OK. The window showing the volume control sliders should change to show sliders for the Microphone and Line inputs. Make sure the one to which you connected the scanner is selected. Change the recording volume by moving the appropriate slider up and down. Use the "Analyze Signal" function under the View menu to take a look at what the signal looks like at different volume settings.
• Try repositioning the scanner and the cable connecting it to the computer. Don't let any extra cable dangle around the computer where it can pick up interference.
• If you've tried the above and it still doesn't work your sound card may not be cooperating. When the program connects to the sound card it asks the card to sample the data at either 22,050 or 44,100 times per second (whatever you the program set to in View|Options|Data Source). Timing is critical in decoding the MDT data, if the card isn't sampling at exactly the rate requested by the program it's not going to be able to decode the 4800 baud data. Instead of using the sound card for decoding you can use a HamComm-type data slicer (under Windows 95/98 only) or an RM100 decoder. The RM100 decoder will produce better results than a data slicer. When using an RM100 decoder the program is able to ignore some noise, not as much as when using a sound card to decode MDT data though.

If you're using using a HamComm-type data slicer and are not seeing anything try reversing polarity. To verify that your data slicer is working correctly download the diagnostic program at http://home.ica.net/~phoenix/wap/slicer.htm.

Where should I look for MDT frequencies?

Try searching upwards from 851MHz, most are in the 851MHz to 862MHz area. Some have also been found in the 450-470MHz range and overseas in the vacinity of 81MHz. Check my frequencies page, as users send me frequencies in use in their area I add them to this page. If you're not sure what you're looking for go to http://web2.airmail.net/lblant1/dfw/download.htm to hear what an MDC-4800 data channel sounds like.

Where can I get a HamComm-type data slicer?

There are several plans on how to build one of these on the web. I used Spectrum Analyzer's All-In-One interface plans to build my data slicer.

Where can I get an RM100 decoder?

You can get an RM100 decoder from Cylex, Inc. They sell the decoders as kits and fully assembled.

How can I stop the MDT window from updating so I can read it?

If you see something appear in the MDT window which you want to read you can click on the hand icon on the toolbar (or select "Hold MDT" from the Action menu, or press Control-H) to "hold" the MDT window. This will keep the program from writing received traffic to the MDT window so you can read it. After you're done reading click on the hand icon again to "unhold" the MDT window. The window will be refreshed so that any text received while you were reading will be appended to the end of the window.

How do I enter aliases for the terminal numbers?

You can enter aliases for terminal numbers in one of two ways:

• The first way is to double-click on a terminal number in the "Active Terminals" window (located in the bottom left-hand corner of the main window). This will pop-up a window in which you can enter an alias for the terminal number you clicked on.
• Another way to enter an alias for a terminal number is to open the Configure menu and click on "Terminal Aliases". This will allow you to add, edit, and delete aliases for terminal numbers. You can also export/import your terminal aliases to/from a file, useful if you run MDT Monitor on two computers.

How can I change the size of the Messages, Active Terminals, and MDT windows?

There are two "splitter" bars, one that runs horizontally and one that runs vertically, that can be moved to change the sizes of these three windows. To locate the horizontal one move the mouse around in the grey area just below the Messages window. You should see the mouse cursor change to arrows pointing up and down. When you see this click and hold the left-mouse button and move the mouse up and down to change the size of the windows. To locate the vertical splitter bar move the mouse around in the grey area between the Active Terminals and MDT windows until the mouse cursor changes to arrows pointing left and right.

Nothing ever appears in the top window, why is this?

The program uses rules which you setup to determine what should be displayed in the top window (the Messages window). When you first install the program there are no rules setup. To setup rules see the next question/answer.

What are rules and how do I set them up?

Rules allow you to instruct the program to perform various actions when MDT traffic matching certain conditions is received. You can have the program play sounds, open windows, log received traffic to disk, and/or display summary information in the Messages window (top portion of the main window) based on received traffic.

To setup a rule open the Configure menu and select Rules. To create a new rule click on the "New Rule" button. This will display the following window:

In the "Name of rule" field enter a name that describes what this rule will fire on or what it is for. This will be displayed in the listbox in the previous window.

The next two fields are used to specify what the program should use to determine whether your rule should be invoked. If you want your rule to do something when traffic is sent to certain terminals you'll fill in the "Sent to matches:" field. If you want your rule to be invoked based on what it traffic is received regardless of to which terminal it is sent you'll fill in the "Message body matches:" field. If you want your rule to be invoked when certain traffic is sent to certain terminals you'll want to fill-in both of these fields.

The program allows you to use wildcards (*'s and ?'s) when you're filling in the "Sent to" and "Message body" fields; a * matches multiple characters, a ? matches any single character, and a # matches any single digit. You can also use ['s and ]'s to match a single occurence of a character in the brackets (examples below). When filling in the "Sent to" field if you don't use any wildcards the rule will trigger only when the terminal number or alias to which traffic was sent matches exactly what you entered, the same goes for the "Message body" field. Comparisons between received traffic/terminal numbers and what you enter are not case-sensitive. Here's some examples of what you might enter in these two fields:

• If you enter "6531" in the "Sent to" field and leave the "Message body" field blank the rule will trigger anytime traffic is received that was sent to terminal 6531 (or to a terminal having an alias of 6531).
• If you enter "65*" in the "Sent to" field the rule will trigger anytime traffic is sent to a terminal number that startes with "65", like 6501, 6506, 6587, etc.
• If you enter "65?4" in the "Sent to" field the rule will trigger anytime traffic is sent to a terminal number that begins with "65" and ends with a "4".
• If you enter "*dispatch*" in the "Message body" field the rule will be invoked any time traffic is received containing the word "dispatch".
• If you enter "*dispatch*zone: 634*" in the "Message body" field the rule will fire anytime traffic is received containing the word "dispatch" followed by "zone: 634" somewhere afterwards. Since there is a * between dispatch and zone the string "zone 634" doesn't have to come right after dispatch in the received traffic, there can be other text in between.
• If you enter "*type: 4[24]IP*" in the "Message body" field the rule will trigger anytme traffic is received containing the string "42IP" or "44IP".

The bottom portion of the window is used to specify what you want the program to do if a rule matches what you've entered in the "Sent to matches" and "Message body matches" fields...

• If you have more than one rule that triggers on similar you may want to check the "Do not process further rules" checkbox. This tells the program to not compare the received traffic to any rules that come after this one if this rule matches.
• Check the "Display message in pop-up window" checkbox if you would like the program to open up a separate window containing the traffic received.
• Check the "Log message in Messages window" checkbox if you want an entry added to the Messages window (the window at the top of the main window) anytime this rule is triggered. The "Configure" button to the right of the checkbox is used to specify what should be displayed in the Messages window.
• Check the "Log message to file" checkbox to have traffic triggering this rule appended to a file on disk. The traffic is formatted like it appears in the MDT window before it's written to the file. Click on the "Filename" button to the right of the checkbox to specify the file to which traffic should be appended.
• Check the "Play sound" checkbox if you want the program to play a wave sound anytime the rule is invoked. Sounds will be played only if your sound card supports capturing and playing of audio at the same time, not all sound cards can do this. If your sound card doesn't support simultaneous playing and recording you can use the RM100 decoder for MDT data decoding and then use the sound card for wave file playback. Click on the "Filename" button to the right of the checkbox to specify the file sound file that should be played.

I monitor more than one system, how can I keep my settings separate?

If you monitor more than one system you should create one Windows short-cut for each system you monitor.

First load MDT Monitor and configure the settings for one of the systems, then save these settings to a profile using the "Save Profile As..." menu item under the File menu. Repeat this for each system you monitor.

Now create a Windows short-cut for each system. In the "Command Line" field enter:

"C:\Program Files\MDT Monitor\MDTMon.exe" Profile.ini

Do you plan on adding support to monitor systems which use the RD-LAP protocol?

Not right now. Before support for this protocol can be added the same information that exists on how to decode the MDC-4800 protocol needs to become available. The information includes things like the frame-sync sequences, the bit interleave, how the error correction works, etc.

Do you plan on making a version of the program available that runs on Windows 3.1?

Nope. I thought about doing this for a while but decided it would be too difficult and would be something I would never use. Nearly all of the functionality that exists in the program is there because it's something I like to use when monitoring or was something that was pretty easy to add. Writing another version would be too much work for me.