Digital Tips is an on-going document containing information submitted by the MARS membership. I hope you find these tips helpful. If you have any of your own, please pass them along and we will include them here!
Ed Finlay, AFE5DM
BEGINNERS FREQUENTLY ASKED QUESTIONS
Q. I have no experience in MARS Digital. How do I get started?
A. 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 your computer soundcard, you will get the audio into your computer. Download one of the programs listed below in answer Nr. 4. and select the mode in use. This setup provides monitoring capability only.
Q. Do I need any expensive TNC (Terminal Node Controller) equipment?
A. 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.
Q. What equipment do I need to work the digital modes in MARS?
A. An advantage to using one of 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.
Q. What is the best software for MARS use?
A. As of 2015, FEMA and the DoD require the use of Mil-Spec M110A for all message traffic on primary frequencies. Please refer to the Understanding M110A tab above for completel information and set up help/configuration. For non-primary frequency use, Air Force MARS uses primarily Olivia 16/1K and MT63.
There are several options for digital modes software. Air Force MARS neither endorses nor specifically recommends any particular software. The three most popular digital modes software packages are:
FLDIGI is easy to set up, provides a clean interface and is supported by a number of the National Emergency Agencies. Download it from: http://w1hkj.com/download.html
DM780 (a/k/a Digital Master 780) is part of a larger package called Ham Radio Deluxe. It is excellent software with lots of extras. http://www.ham-radio-deluxe.com
MULTI-PSK includes many different modes and presents them all on one page. While it covers many modes and interprets the data very well the graphical interface does confuse the eyes somewhat. You can find this software at http://f6cte.free.fr/index_anglais.htm
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 included in the software listed above.
Q. Why does my radio suddenly go into transmit without my control?
A. WINMOR is an ARQ (Automatic Repeat Request) mode that is a type of PACTOR that uses the soundcard instead of a TNC. Information on this and several other feature of MARS specific software can be found at http://www.winlink.org/. Notice that there is a MARS Link which requires some registration. If you are a longitime 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 transceiver goes automatically into transmit. This is the nature of ARQ.
Q. Do I really have to memorize all of the Q and Z signals?
A. No, just a few common ones. See the North Central Division Training Guide for a complete list for ready reference. Note that most of the various digital modes programs include an option for setting up pre-defined texts where you can save your own frequently used messages including these. Refer to the North Central Division Training Manual for listings of these.
There is a document located that will provide the basic information required for stations to understand the Q and Z signals and shorthand operation on digital nets.
Q. Where can I get specific help for specific problems?
A. All of the 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 a great time to ask your questions and get assistance, especially with M110A!
SOUND CARD CALIBRATION PROCEDURE
It appears that most computer soundcards 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:
- Download MMTTY (an excellent freeware RTTY program) from http://www.qsl.net/mmhamsoft
- Install and open MMTTY by running the .exe file you downloaded.
- In MMTTY, go to Option --> Setup MMTTY --> Misc page, and click Adj button in the ‘Clock’ box.
- Tune your radio to WWV at 2.5, 5 or 10 MHz.
- Tune into the tick sound.
- 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 lines that correspond to the time "ticks" sent by WWV.
- Click the upper point of the line.
- Click the lower point of the line.
- 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.
- Close MMTTY and open your receiving program.
- 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 category have produced systems and ARQ protocols that are similar to Pactor but make use of the computer sound card. 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 site you will find a download path to WinLink FTP for all of that is needed to get this free software. Download the tutorial and read it thoroughly.