ARTICLE

May 2004

Defense Dept. Studying Options To Lower Cost of GPS Receivers

by Sandra I. Erwin

Information-age technologies such as software radio and miniaturized electronics could, one day, make it possible for soldiers to combine their global positioning satellite receivers and handheld radios into a single device. Experts caution, however, that fears of enemy jamming and tampering could make any software-based GPS technologies undesirable for military use.

The acceptance of a software version of GPS would be highly dependent on the success of the Defense Department’s $14 billion Joint Tactical Radio System. Once the JTRS radios enter service, possibly by 2008 or 2010, it is conceivable that one of the wavebands on the radio would be the GPS system, experts said. JTRS is intended to replace every radio system in the Defense Department.

The advantages of consolidating voice, data communications and GPS navigation in a single device boil down to cost savings and convenience. The Army, the heaviest user of GPS services, is fretting over the cost of new GPS receivers, which go for $2,000 to $3,000 each.

These next-generation receivers—to be fielded in the coming years—are much more sophisticated than commercial devices and, most importantly, are in compliance with the encryption and anti-tamper requirements mandated by the Defense Department. The steep prices for these receivers, however, mean that not every soldier will get one, Army officials note.

At various industry conferences in recent months, Gen. Paul Kern, head of the Army Materiel Command, questioned why AMC must pay $3,000 for a GPS receiver, while Radio Shack sells devices for $275. As thousands of soldiers shipped off to Iraq during the past year, many bought their own commercial GPS receivers, which tend to be more user friendly than Army-issued devices, although they are not as precise.

Experts attribute the high cost of military receivers to the anti-tamper chip, called the GPS selective availability anti-spoofing module. SAASM is mandatory on every GPS system purchased by the Defense Department.

But a program official at the GPS joint program office said this technology is not necessarily the biggest cost factor. A SAASM receiver generally consists of a government-designed data processor, a vendor-designed SAASM module and a vendor-designed host GPS receiver.

The cost of such receivers can vary widely, said the JPO official. The hardware alone is inexpensive. But other costs add up, such as implementing anti-tamper technology, protecting GPS cryptography and hardening the devices for tactical applications.

Concerns about the affordability of GPS receivers have prompted a review of the SAASM policy, said Air Force Col. Steven MacLaird, program director for the joint tactical radio system. This program is developing the software that will allow the Defense Department to convert all military radios to a JTRS standard, effectively making radios function like PCs.

The GPS could, one day, become one of the JTRS software applications, MacLaird said in a presentation to the Institute for Defense and Government Advancement.

“We are being asked about the possibility of doing encryption with commercial technology and do the GPS waveform, so we can provide it across the battlefield,” McLaird said.

Another option being considered is whether to make the SAASM policy more flexible, possibly reversing its mandatory status. Once they became aware of how expensive the receivers are, senior officials questioned whether every soldier in fact needs a SAASM receiver.

The Pentagon provided $50,000 for a study to identify “what users really need SAASM,” MacLaird said.

Michael S. Frankel, deputy assistant secretary of defense for command, control and communications, said that a GPS waveform for JTRS is “being considered,” but not yet funded.

There are obvious advantages to having GPS services in the radio, he told National Defense. But he predicts that security concerns will prevail over the convenience factor. “I don’t think that time is here yet.”

The Army, meanwhile, is studying ways to standardize GPS equipment and limit the proliferation of non-approved GPS devices in the field. The GPS joint program office is participating in these studies, to ensure that any changes don’t compromise cryptography or security, the official said. The Joint Program Office and the National Security Agency must approve each receiver design before it can be produced and sent to the field.

The tight security procedures associated with SAASM make it questionable whether any software-based versions of GPS would ever be acceptable to the Defense Department, said the JPO official.

The current policy prohibits software-based military receivers. The JPO, he said, has no plans to transition SAASM to a complete software solution.

“It is not in the best interest of national security to develop a military GPS receiver where SAASM security functionalities reside in software and the receiver does not use approved ‘protection’ technologies as implemented in the SAASM chip,” he said.

Nevertheless, the Army’s Research Development and Engineering Command is working with Navsys Corporation to demonstrate a secure software-only GPS, called the Software GPS Receiver. The SGR is “partially compliant” with the JTRS architecture.

The GPS Joint Program Office approved this demonstration, and drafted revisions to current Defense Department policies. The proposed changes address future planning for GPS architectures and how they will be carried out. “It highlights an interest in software GPS programs,” the JPO official said.

“The Joint Program Office is observing this effort, but has yet to endorse or implement a similar, software-based crypto security program.” ND

—Sandra I. Erwin

Back To Top