Tuesday, August 4, 2015

Contacting MARS: A Saturday on the Radio

                The ship was off the coast of Bermuda on May 9th and 10th and it was time once again for the annual Amateur/ Military Affiliated Radio Service (MARS) cross band operations test.  I had been sent information about the event via PACTOR email from Brad, KA3YAN out of Charleston, SC, so I was ready to work the bands contacting stations via single side band and also copy the secretary of defense’s message via various digital teletype modes.

                The way that the operation works is that the radio operators at the military station would transmit a call on a military frequency and announce the listen frequency in the nearby amateur band.  The amateur, in turn, would use the split capabilities of the HF rig to listen to the military frequency and transmit on the announced amateur frequency.  The teletype was sent on a published frequency at a certain time and with a certain mode to be copied and printed by the receiving station.  This text can be mailed to the appropriate MARS liaison for a certificate.

                The military stations that were participating spanned the globe and were either MARS stations on military facilities, or in a few cases, museum ships that have retained MARS capabilities.  Four branches of the government were represented by various stations: US Army, US Navy/Marine Corps, US Air Force, and even the US Coast Guard got involved.  The flagship station was station WAR located in the Pentagon.

                My little pistol station consisted of a 100W HF radio feeding a remotely tuned sloper antenna with about 30 feet of wire.  The antenna was 100 feet off of the sea and grounded to the ship’s structure.  It may not have power or much wire in the air, but with a nearly perfect ground plane and no nearby RF interference sources, it is a fine station indeed.  The military stations were using a variety of antennas including Log Periodic beams to wire arrays.  Many of them were also using amplifiers to put out a better signal.

                During the course of the day, I worked stations as far to the West as Indiana and Texas,  as far north as Upstate New York, as well as a number of East Coast stations.  I did manage to work WAR on 20 meters, and the USCG Atlantic control station NMN.  My favorite was working NWKJ, the Ex-USS Yorktown (CV-10) in Charleston, SC Harbor.  I have a special affinity working ship to ship stations.  I was able to work stations on the 40M, 20M and 15M bands to round things out.

                Copying the Secretary’s message proved to be a bit of a challenge, as most of the digital modes being used were fairly unusual in today’s amateur world.  I was able to copy two stations and used four different modes to get the copy.  The first was from station AAC on 13 MHz which is an Army station that was transmitting on Military Standard 188-110 FSK.  This is a wide band RTTY station that operates at 75 baud and is 850 Hz wide.  The standard amateur RTTY is 45 baud and 170 Hz wide.  Fortunately for me, the FLDigi program I use has a setting for just this mode and I had fairly clean copy for the message.  The second station was Navy Station NBL in Groton, CT.  They transmitted on 14MHz, just above the amateur 20M band in Amateur RTTY, AMTOR Mode B, and MT63.  FLDigi was able to copy them all, but I had to cheat with the AMTOR by using the SITOR setting in the program.  Since AMTOR is the HAM variation of SITOR, I was able to get clean copy.  MT63 also proved to be a challenge as there are a number of variations to the mode.  I could tell from my waterfall that it was 1 KHz wide, but whether it was long interlace or short wasn’t readily apparent.  I simply switched between the two and saw which one it decoded (it was 1 KHz Long). As NBL gave several RYRY strings prior to sending the message, it was easy to get tuned in and on the right mode.

               I was able to get my copy of the SECDEF's message off into the US Military postal system in Djibouti and a few weeks later a QSL card from USAF MARS was in the mailbox.  As of this writing, I am still waiting for the Army and Navy QSL cards, but good things come to those who wait.

                It was an enjoyable exercise, and made me think outside my normal comfort zone with radio and mode configurations, and perhaps in some civil emergency, such skills will be put to use for real.  For me, experimentation and being prepared to lend our radio skills to those in need is what amateur radio is all about.

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