logo for long-range communications storiesUnit-level Logistics System blasting -- is there a better way?

by MAJ Kurt Wadzinski

The 1st Cavalry Division is changing the way units pass logistical traffic.

The current system uses the Army�s Single-Channel Ground and Airborne Radio System to conduct a �frequency-modulation blast.� A unit has to compile Unit-Level Logistics System information, then connect computer to SINCGARS through the data port and try to send the data. This is a burst transmission that usually takes several attempts to pass the data at a data rate of 2,400 baud.

After the unit sends the FM blast, it must call the distant end to ensure the destination unit receives a complete FM blast. There�s no other way to verify if the FM blast was successfully received. Many times a unit only receives part of the blast. Since the FM blast wasn�t complete, the sending unit must try again.

National Training Center challenges

Before rotating to the National Training Center at Fort Irwin, Calif., a support unit trains on conducting the FM blast again and again � for example, through a company situation-training exercise, task-force exercise evaluation and other training events leading to NTC. But no matter how much a unit trains, it doesn�t quite take into account the conditions at NTC. There distance becomes a big factor; as battalions and their attachments move through the �box,� they move out of line-of-sight of the forward-support battalion. This creates an even bigger problem in completing the FM blast, much less contacting FSB to ensure it received the FM-blast traffic.

Once units are out of LOS, they must retrans their net by placing a retransmission team on a hilltop or another piece of terrain to create an LOS connection between the two stations. Then the units try to pass their traffic through the retrans site. Truly challenging! What will the unit do if this fails? The unit tries again and again, until they go back to the �sneaker net.� Eventually the unit has to send soldiers in a humvee with a disk of ULLS information; essentially the soldiers drive to FSB with the FM blast in hand. This can be a difficult task when there are several units spread throughout a battlefield trying to blast more than once a day.

Beyond-line-of-sight radio traffic challenges

There are three basic ways of passing radio traffic beyond LOS. The first way is by using a high-frequency radio. Using an HF radio doesn�t require special access to a satellite; instead, the radio works in the frequency range of 1.6 to 30 megahertz. HF radio bounces the radio signal off the ionosphere to the distant radio to enable BLOS communication.

The second way is by using a satellite radio such as a single-channel tactical-satellite manpack radio. The radio sends its signal to a satellite that sends the signal to the distant radio. The problem with using satellite radio is that the unit must receive satellite access. Unfortunately, satellite access doesn�t get allocated to pass logistical traffic for support units.

The third way to pass BLOS traffic is by using a retransmission site. A retrans site must be placed between two sites that are out of LOS with each other. For retransmission to work, the retrans site must be in LOS with both distant radios trying to communicate. What happens if the retrans goes down or is destroyed? The units using the retrans can no longer communicate.

1st Cavalry solution

The 1st Cavalry Division is passing ULLS-Ground information through the new HF radios (AN/PRC-150). Those radios have a myriad of new capabilities over the old 1970-80 technology of improved HF radio. The 1st Cav is using HF communications� capabilities to solve the logistic-traffic problem.

By placing an AN/PRC-150 using a near-vertical-incidence skywave antenna (sometimes a long whip) and a computer loaded with RF-6710 HF email at two locations � not dependent on terrain or distance (see following figure) � 2d Brigade Combat Team has validated the system. The RF-6710 HF email is a Microsoft Outlook-based program that looks almost identical to Microsoft Outlook, making it very easy for soldiers to learn and use. This HF email system passes data at 9.6 kilobytes per second using the BLOS HF frequency range and at 16 kbs using the LOS FM frequency range (in case units are close enough to take advantage of the higher data rate).

Topographical map of units in NTC central corridor blasting ULLS data BLOS 2d Brigade TOC and battalion UMCPs in NTC's central corridor blasted ULLS data using HF to 15th Forward Support Battalion in the southern corridor (BLOS).

The HF email also takes advantage of the RF-6710�s automatic-repeat request error-correction mode. ARQ ensures every email that shows up as being sent has actually passed successfully at 100 percent; units no longer have to call the distant end after sending every message.

Cav�s radio networks

The 2d BCT deployed an AN/PRC-150 with each unit-maintenance collection point and FSB. The BCT deployed two networks. One network was a logistical one that included six sites: three task-force UMCPs; the headquarters and headquarters company of the brigade, colocated with the Signal and air-defense artillery slice; and the engineers� UMCP � all talking to FSB. The second network was a command-and-control network that included two sites: the tactical-operations center and the commander.

The C2 network ensured communication if the units went BLOS and weren�t covered by retrans. The network also used the AN/PRC-150�s digital voice 600, which allows the user to communicate through a signal-to-noise ratio of 1:1. (In layman�s terms, it allows you to talk through the night when frequencies have a tendency to be more difficult to communicate over.)

AN/PRC-150 provided 2d BCT with a reliable means to communicate and send its logistical traffic. In the future, these new HF radios will provide 1st Cavalry Division with other mission-enhancing communication capabilities. The 2d Brigade looks forward to integrating the radios into Colt Teams and sees them as a possible solution to communicating with its widely dispersed scout teams. Both units routinely run into BLOS communications difficulty due to distance and terrestrial limitations.

HF communication has come a long way in the last 20 years, and 1st Cav is using the advantages it provides to enhance the division�s communication structure.

MAJ Wadzinski is the S-6 for 2d (�Blackjack�) Brigade, 1st Cavalry Division. He has also served with 10th Mountain Division (Light) as the 1st Brigade S-6; was the Office of Military Cooperation�s J-6 automation and communications adviser for the Kuwaiti defense forces; and spent a year with the private company TRW working with the Force XXI Battle Command Brigade and Below System.

Acronym QuickScan
ARQ � automatic-repeat request
BCT � brigade combat team
BLOS � beyond line of sight
C2 � command and control
FM � frequency modulation
FSB � forward-support battalion
HF � high frequency
Kbs � kilobytes per second
LOS � line of sight
NTC � National Training Center
SINCGARS � Single-Channel Ground and Airborne Radio System
ULLS � Unit-Level Logistics System
UMCP � unit-maintenance collection point

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