MRS-MDS Tribute

Tribute to the MRS & MDS Systems Operators in Region Ten

In the Beginning
For nearly 30 years traffic was passed outside the local regions of Navy-Marine Corps MARS via teletype by a method called the Major Relay System, or MRS. No computers here. Members who were part of the MRS operated mechanical teletype equipment. Usually the messages were set up and sent using the torn tape method. Long rolls of paper about an inch wide were fed into a special sort of typewriter called a reperferator or just reperf machine. These may have been stand-alone devices, or incorporated in a full teletype machine such as the Model 28. The operator would type the message and the machine would punch the paper creating a pattern of holes. Once the message(s) were set up the paper tape was torn off and could then be fed into a teletype machine designed to "read" the tape and convert the pattern of holes in the paper to the Baduot code for radio transmission. This mode of transmission was called radioteletype, abreviated RATT or RTTY. Often it was written as teletypy, one reason being the word teletype was actually a trademark of the Teletype Corporation, founded in 1906. Local teleype nets were held daily for picking up out bound traffic received from voice nets and delivering inbound traffic for relay on local voice nets. This was a time consuming process which demanded extreme attention to detail by every MRS operator in the system.


World War II ArmyMajor Relay Station	Model 28 send and receive floor model	Inside of a "torn tape" reperf machine.

One of many table top repef machines for making "torn tape"	Unit for reading "torn tape" for transmitting	A 1,000 ft roll of 1" paper tape

This is just a very small sampling of various teletype equipment used.

It in no way respresents all the aspects of RTTY opperations.

Sample of punched tape. This tape reads:

DE NNN0AS0 REGION TEN NMC MARS K

(The black dots are actually holes in the tape.

The line of smaller holes down the center are for the feed sprocket)

If you try to figure out the characters from the hole pattern there are

some function controls that may throw you off. 7th character from left,

between "NNN" and "0" (zero), is the figures function. It tells the TTY

printer the following are numerals not letters. The character after the "0"

is the letters function telling the printer to shift back to letters. This

sequence repeats for the zero on the end of "AS0". The first part

of what this tape would actually transmit is (DE thru AS0):

D E [Space] N N N [Figures shift] 0 [Letters shift] A S [Figures shift] 0 [Letters shift] [Space]

As mentioned earlier, these were manually set up. No spell check. One typo could

result in transmission of a completely garbled message.

Phase II (so to speak)

In 1993 MARS began a brand new system, the MARS Data System, or MDS. This consisted of a series of stations set up as switches, later called MBOs. Each switch was capable of operating on two or more frequencies at the same time. usually one VHF and at least one HF. Some operated two, three, or more HF frequencies simultaniously.

There have been four levels of operation in the MDS: RDN = Region Data Network*; ADN = Area Data Network; NDN = National Data Network; and, IDN = International Data Network. (The latter two were forwarding only systems, not accessible to local members or Traffic Reps). An RDN station served primarily as a point of orign, or point of final delivery (in the MDS system) to and from local members. RDNs connected with ADN, NDN, or IDN switches to forward traffic in and out of the Region. Many switches operated at more than one level.

*After the addition of Areas to the MARS administrative structure the RDN level was eliminated in Pac Area. Those stations became ADN switches.

The advantages of MDS over MRS were huge, but the initial learning curve and problem-solving were equally challenging.

Advantages included no manual hardware in the sense of the teleype systems, everything was computerized. There was no need to print anything to paper or create "torn tapes" in the forwarding process. The system was fully automated for forwarding. It was capable of automatic distribution to several geographic areas at one time for multi addressee messages. Rarely was there any need to enter the messages separately. The system had auotmated tracking as the messages moved through the system from one switch to another.

Another huge advantage of the MDS over the MRS was the speed at which a message could be delivered. Miltary RTTY was faster than commercial, but still was only 100 WPM, 75 Baud rate. HF MDS ran 300 baud (4 times faster). VHF could transfer a message at 1200 baud. A rate 16 times faster than RTTY.

An operator did not have to be in attendance for traffic to get forwarded to the next leg of the system. Thus no waiting for an operator to be available to receive, process, then forward a message, three steps that rarely took place at the same time.

At predetermined times every hour (24 hours a day, 7 days a week) each switch would connect to any number of other switches in the system and automatically forward any traffic that switch could handle. For example, a switch in Seattle would connect to MDX in Portland and forward traffic destined to go out of the region. MDX would connect to switches in California, Hawaii, the midwest, or even the East coast passing traffic to be picked up from those switches, or passed on to yet another switch in the relay system.

At the same time the Seattle switch (in our example) would pick up any incoming traffic from the Western Pacific, East coast, or other areas around the world that had come into MDX for delivery to addressees in NW Washington, or perhaps pass them on to another switch, say in Alaska or eastern Washington.

A few of these MDS stations, such as NNN0NUW at Whidbey Island NAS, specialized in maintaining mail box systems on the MDS. U.S. Navy and Coast Guard ships with MARS stations could pick up and deliever their MARS traffic through them.

Depending on the timing of the switchs a message could theoretically get anywhere in the world ready for delivery within a few minutes of input into the MDS. The MRS would likely be at least 24 hours, even two or three days, from origin to point of delivery.

After 15 years of routing traffic around the country and around the world via the MDS, that system has now gone silent in favor of

WinLink; Phase III(?)

Below are a few photos of some Region Ten (formerly Region Seven) stations that operated the MDS over the 15 year period from 1993 to 2008.

The AA4RE software provided split screen operation so one could monitor any two of several aspects. A status line in the middle showed all stations connected and their port IDs. Ports could be controlled individually in the event of urgent need.

MDX served as an RDN, ADN, NDN, and IDN connecting with switches all across the country as well as providing local access for members.

It's kinda hard to see just how many radios and TNCs are on line here.

MDX operated multiple HF ports and one VHF port. Capable of connecting simultaniously on up to 5 different frequencies.

MDX was the only switch in the Region to operate continuously, from one location, under one sysop for the entire 15 years of the MDS.

MVB served as alternate for Region Ten NDN service spliting the load with MDX in and out of the region, and as backup to MDX and other switches in the region.

In 15 years there were only two times that MDX had any serious outage.

For all who contributed to the MRS and MDS systems, these members donated thousands of hour,

and an equal contribution in monitary value both in equipment and the power to run it. Their hard work

and dedication to the MARS mission is truly akin to the "Iron Men" * of days gone by.

* "Iron Men" was a label given to operators long ago who stayed up sometimes half the night looking for

an opening in propagation, usually on 160 meters, so they could forward traffic on CW.

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