AIR FORCE MARS: Providing the Reins of Command--in Emergencies

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North Central Area Digital Tips

Digital Tips
Digital Tips is an on going document containing information submitted by the MARS membership. I hope you find these Tips helpful and if you have any of your own Digital Tips, please don't hesitate to E-Mail them to me



1.   I have no experience in MARS Digital how do I get started ?
2.   Do I need any expensive TNC (Terminal Node Controler) equipmaent ?
3..  What equipment do I need to work the digital modes in MARS ?
4.   What is the best software for MARS use. ?
5.   Why does my radio sudenly go into transmit without my control ?
6.    Do I really have to memorize all of the Q and Z signals ?
7.    Where can I get specific help for specific problems ?


  1.  Read as much of the background material from the internet on general  computer sound card use.   If you will  simply attach an audio cable from the  external speaker jack on your radio, to either the line input or the mic input on you computer soundcard, you will get the audio into your computer.  Download one of the FREE programs listed  below in answer Nr. 4. and select the mode in use.   This setup  provides  monitoring capabilities only.

2.  No.   A simple interface is all that is needed.  Interfaces that work directly off of a USB port are becoming very popular however if your computer has Serial Ports  (Com Ports). many interfaces work very in that configuration.  There are advantages and disadvantages to both systems.  

3. An advantage to using one  the later USB interfaces is reduction of possible conflicts from your  computer soundcard when other sound programs may be resident.  Here is a list of known interfaces currently in successful use in MARS now. There are many others on the market and no attempt is made to list them all.

Several models of RIGBLASTER   Range    $300 to $59.00
Signallink .................................................    $109 to $79.00 
BUXCOM Rascal.....................................    $ 69.00   $39 Kit.

There are many others and generally you pay for any extra bells and whistles.


FLDIGI is my preference since it is easy to set up, provides a clean interface and is supported by a number of the National Emergency  Agencies.  Download at:

DM780 is part of a larger package called Ham Radio Deluxe.  It is excellent software with lots of extras..

MULTI-PSK  includes many different modes and presents them all on one page.  While is covers many modes and interprets the data very well  the graphical interface does confuse the eyes somewhat.

Of course there are other programs but all that is really needed to get started in our current system is to download one that includes those modes ncluded in the software listed above.
There are other  modes being developed within MARS that really enhance our ability to communicate. But get started first  MFSK, Olivia and MT-63 first and then develop further capability with the others.  

WINMOR is an ARQ  (Automatic Repeatt Request) mode that is a type of PACTOR that usese the soundcard instead of a TNC,   Information on this and several other feature of MARS specific software can be found  at ---
Notice that there is a MARS Link which requires some registration.

5. If you are  a long time user of  Packet, Amtor or Pactor, This question  may surprise you but it has been asked more often than you may think.  Even some long time users of RTTY and even PSK 31 are surprised on their first try at one of the ARQ (Handshaking ) modes that after certain commands their tranciever goes automatically into transmit.  This is the nature of ARQ.

6. No, just a few common ones. See the NC Division  Training Guide

7.  All of the free software mentioned above have help files and some have some very detailed "Tutorials" for new users.  The multimode net on Wednesday evening (local) or  0001Z  Thursday usually will have several experienced experts checked in and that is time to ask your questions.

There will be time when you need to calibrate your sound card wtih your software and different programs offer differeint methode.  I have included here
an easy method for calibration that you may find helpful .

SOUND CARD CALIBRATION PROCEDURE It appears that most computer soundcard's do not have their clock frequency set very accurately as they come from the factory. If you are having difficulty copying the digital modes or are receiving reports that your transmit signals are not exactly right, your soundcard clock frequency may be slightly off. Don't shoot your computer, you can compensate for this by adjusting the soundcard parameters in your receiving program. Many of the receiving programs have a method of determining how far the soundcard clock frequency is off, but they are not always easy to use. Here’s a method that is fairly easy to use and will allow you to adjust your soundcard to WWV with an error of less than 1 ppm;

  1. Download MMTTY (an excellent freeware RTTY program) from
  2. Install and open MMTTY by executing the .exe file you downloaded.
  3. In MMTTY, go to Option --> Setup MMTTY --> Misc page, and click Adj button in the ‘Clock’ box.
  4. Tune your radio to WWV at 2.5, 5 or 10 MHz.
  5. Tune into the tick sound.
  6. Continue listening to the sound for a while. You should listen for at least 3 minutes; but, listening longer will improve accuracy of the following steps. You will see one or more nearly vertical line that corresponds to the time "ticks" sent by WWV..
  7. Click the upper point of the line.
  8. Click the lower point of the line.
  9. You have now calibrated the MMTTY software. (Please note that this did not change anything on the soundcard, only in the software.) Make a note of the frequency that is now displayed in the box.
  10. Close MMTTY and open your receiving program.
  11. In your receiving program locate the setup option that allows you to set the sample rate for the soundcard and enter the frequency found in step #9. For example, in MixW: got to Configure --> Soundcard setting --> Samplerate.    

More recent developments in the Winlink and Winlink 2k catagory have produced systems and ARQ protocols that are similar to Pactor but make use of the computer sound card.   Specifically "RMS Express" is now providing a unique message system with provisions for immediate contact and/or relay with message centers by direct internet, direct radio contact or a combination of both providing means of  selecting which is best suited for the situation.  On the Winlink 2000 sites you will find a download path  to Winlink FTP for all of that is needed to get this Free software.   Download the turorial and  read it thouroughly..   








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