1. Advanced Digital Modes: M110A Digital Modem Terminal & Army Terminal Software
Ken Heitner AFA3PB / AFD3AL
David Maples AFA3WZ / AFF3VA
NE Division Conference
September 2015
Good afternoon: Some of you from the old Region 2 may have heard me before talk about digital modes. I started doing this over a decade ago. What I will say here is the latest stuff.
We have made steady progress in digital operations on HF. In particular, the MIL-STD A Digital Modem Terminal did not exist then. So please pay attention. These new modes for HF digital communications are what we will now be routinely using.

2. Why Digital Messaging?
Allows Emergency Traffic to be Handled Quickly and Automatically
Works with Existing Systems when They are Available
Has Potential to Interface with Military Stations
Messaging Mode is Familiar to Most Users
Can Effectively Utilize Available HF Channels
It is important to remember that in an emergency, there is a lot of traffic. And it has to be handled quickly and efficiently. These new systems all follow formats that are familiar, that is: . This means the main task of the operator is focused on preparing the message. Starting with the this format is very advantageous. Using it in MARS should be a simple transition. It is also important for interoperability with the military.

3. What is Needed Here? Start with Standard Personal Computer components:
Soundcards, and
USB or Serial (COM) Ports
All Critical Features are Built into M110A Digital Modem Terminal (as software)
Additional Features in Army Automated Message Terminal
These are Linked by Virtual COM Ports
We start with a personal computer with a sound card and a USB or serial port. We add to this software that serves as the MIL-STD modem.
The sound card is the input and output device that connects to your radio. The USB or serial port serves to key the radio.
In addition, we add software for an automated message terminal. This helps both compose and receive message traffic. All of these are linked by software in your PC.

4. M110A Digital Modem Terminal
Meets MIL-STD A Requirements
Phase Shift Digital Modulation & Demodulation
Digital Signal Processing (DSP)
Forward Error Correction (FEC), and
Radio Tuning Errors
Works with Most Sound Devices
Available:
The key software in this package is the M110A Digital Modem Terminal.
This demodulates the incoming Phase Shift Keying signal from your received audio via the sound card.
It automatically adjusts to the baud rate of the incoming signal.
The modem generates the outgoing signal by the reverse process. It also keys your radio to transmit. You choose the baud rate to send traffic based on experience with the HF circuit.

5. Army Automated Message Terminal
Most Critical Functions of Digital Message Transfer are Handled in Software
Operator Sets or Selects:
Message Format (Standard types)
Transmission Baud Rate (depends on link)
Transmission frequency and choice of antenna
Received Messages are saved automatically as files
Available:
The Automated Message Terminal simplifies receipt of messages by saving them as file where designated.
This feature also helps with any needed Decryption.
In the transmit mode, the AMT helps format several different types of standard messages. This simplifies message handling. There are detailed manuals for both the M110A – DMT and the Automated Message Terminal.

6. Software Package Linkage
M110A DMT and Army Automatic Terminal must be LINKED!!
This is done by Virtual COM Ports
There are various packages that work:
Recommend: Virtual Serial Port Manager by K5SR – Very easy to use
Create at least one serial port pair to form required link
Available:
Virtual COM ports are used to link the M110A- DMT and the Automated Message Terminal. The Virtual Serial Port Manager is one of a number of programs that can do this job.
You have to first look at the numbering of the physical COM ports on your PC.
If you are running a lot of external gear, you may have 8 or 10 physical COM ports. You have to number the Virtual COM ports with higher numbers. However, do not go too high in the numbering. That may also lead to problems. See the URLs noted on slides

7. M110A Digital Message Term.
This is the M110A dialog box. It is pretty complex. In here you designate:
-What sound card is being used
- What serial port keys the radio
- What baud rate you will send at
- What COM port link you are using
And a bunch of other things.
YES. Read the manual carefully. Perform the checks on your computer for latency and sound card time base accuracy. If you fail the checks, the modem will not work well or at all.

8. Army Automated Message Terminal
The Automated Message Terminal is also packed with features. You should read its manual carefully. We do not use all these features at the present time. The most important one is to select the correct COM port.
This completes the link so the received and transmitted traffic is handled via this screen. Choose directories to store the received and transmitted messages so you can find them later on.

9. What Does It Look Like? Virtual Serial Port Manager
The Virtual Serial Port Manager is simple by comparison. You get to see your physical COM ports and their numbers. Then you can add pairs for virtual COM ports to link your software packages. You only need one pair of serial ports for this project. There may be other requirements in the future.
So it is a good piece of software to have.
[Just as a hint, I keep 3 x 5 cards on my PCs with what equipment the COM ports and Sound Cards are nominally connected. Helps some times to know.]

10. What Does the Future Hold?
The MIL-STD A Modem is part of the standards for ALE Radios
Military ALE Radios may have this Modem as part of the hardware
The MARS-ALE software already has the MIL-STD A modem built in.
This offers the capability to automatically transfer messages to the destination radio
Future decisions will affect what happens with in AF MARS
Two important point here: First, the MARS-ALE software package also contains an advanced version of the M110A modem. In practice, one your ALE station links to another, it will send a message (error-free) automatically. The receiving station will acknowledge automatically. Very Nice!
Second, there are other modem modes that could be used in the future that also comply with the MIL-STD. More work is needed to develop software for these modes to see if they are better choices.

11. For Additional Information
Contact Ken AFD3AL
to:
WL2K Message to: AFA3PB
TPN Message to:
Phone:
Join The Digital Revolution in MARS Today !!!
You Might Just Learn Something New !!
In closing I want to say that I am only too willing to help you set up either your MARS-ALE/M110A station. Please feel free to contact me as noted on this final slide. I will try to do what I can to help you with your setup. I am the process of setting up this digital mode at my station. I have also set them up at the Pentagon MARS Station. So I believe I am qualified to help. I look forward to hearing from you soon. (Ask for questions !)

12. And What About the Other Digital Modes & Nets??
TRR 1&2 –10AM & 7 PM EDT – MFSK16
TPN – Pactor 1,2,&3 – TPB, TPE, TPG, TPM – AFB2MC, AFC2MC, AFE3MC, AFC4MC are active BBSs
WinLink 2000 MARS -RMS Express:
Available from:
-Setup Uses MARS Service Code (See me!)
ALE in Transition to work with Army
Yes, there is other digital activity besides M110A \-DMT. So this slide is a summary with critical information on each of the other modes or nets.
TRR 1&2 is a digital net conducted entirely in MFSK16 using Q and Z signs. Come join us.
TPN is Transcon Pactor Network. This is completely automated message handling. The same goes for Winlink 2000 MARS. Messages are delivered automatically in an format. See me for the service code.
We continue to experiment with ALE. Army and AF MARS will work together on this.
All of these efforts need more support. Need I ask from who?? More questions, see me.