INDUSTRY INTERVIEW: Comtech Mobile Datacom Corp.
President
Comtech Mobile Datacom Corp.
A: With the Comtech Blue Force Tracking- High Capacity [BFT-HC] transceiver, situational awareness will become much more accurate since the time between position report updates will be dramatically reduced. The additional available bandwidth or dramatically improved download speeds will also enable new features to be implemented such as over the air software upgrades and over the air downloads of images and map overlays.
Q: What data rates does the new BFT-HC transceiver offer?
A: The BFT-HC offers seven selectable forward link data rates—230 kbps, 130 kbps, 52 kbps, 21 kbps, 5.6 kbps, 2.6 kbps and 660 bps—and two selectable return link data rates.
Q: Why does Comtech offer so many different data rates?
A: In a word—flexibility. This wide range of data rates maximizes the customer’s flexibility in choosing the most cost-effective satellite service for any given theater. For instance, in a pine forest or tropical jungle, a lower data rate creates additional margin, enabling the signal to penetrate through vegetation. Alternatively, for large geographic areas, lower gain satellite beams can be optimized with an assigned data rate. All the above data rates are either in use today or have been tested over an INMARSAT satellite.
Q: Is Comtech going to be considered for the next generation BFT transceiver contract even though ViaSat was selected for the initial prototype contract?
A: We believe our solution provides many life cycle cost and real-world performance advantages that in the end will make it the preferred choice. For instance, the high-gain electronically steered antenna will reduce satellite charges or enable operation in dense foliage or other disadvantaged areas. Our ability to provide full backwards compatibility with the BFT 1 system reduces rollout costs and maximizes operational flexibility, especially during the BFT 2 system’s deployment phase, which could take years. Our modular design features a field replaceable antenna that not only reduces operating and maintenance costs, but supports easy upgrades to other frequency bands.
Q: What are the differentiators of the new Comtech BFT-HC transceiver and the new Comtech BFT network?
A: First and foremost, we have designed an antenna that captures energy from the satellite over every square inch of real estate allocated to the BFT transceiver, which, according to BFT 2 specifications, remains at 8 inches by 8 inches for every ground mobile platform. Maximizing the antenna aperture in this way results in a high-gain antenna—7 to 10 dBic gain—that will result in cost savings because less power needs to be purchased off the satellite; enables high data rate operation in dense foliage; enables high data rate operation on lower cost/large foot print satellite beams; and ensures operation of up to 230 kbps—nearly twice the BFT-HC requirement.
Second, Comtech’s BFT-HC is fully backwards compatible with BFT 1, a critical feature that saves real money by enabling BFT 1 and BFT-HC transceivers to operate on the same satellite channel. The Comtech solution also maximizes flexibility for the customer during BFT 2’s critical rollout phase. Third, Comtech’s solution was designed from the start as a mobile platform. The High Capacity Waveform uses advanced LDPC technology and other specialized techniques to obtain optimal performance. Finally, a key Comtech network differentiator is the NSA-reviewed BFT 1 security features that, along with other stringent systems security features, have been fully retained in our BFT-HC system.
Q: Why is BFT-HC designed to operate over so many different L-band satellites?
A: Comtech’s BFT 1 service is currently in use on seven different commercial satellite systems. These choices give customers flexibility not only in terms of pricing and features, but also in the system’s deployment and use. Comtech’s ability to seamlessly operate over multiple satellites and overlay coverage from different service providers enables us to provide a completely independent backup satellite service, ensuring critical redundancy is available where it is needed. Finally, having a diverse selection of satellite providers ensures Comtech is able to provide the highest possible elevation angle from the user to the satellite for the best possible satellite visibility.
Q: What are the advantages of multi-user detection over power control?
A: Simply put, multi-user detection [MUD] works better in a real-world mobile environment with the geosynchronous satellites required for BFT. In order to get the required BFT capacity from CDMA/power control, the incoming signals must have their power levels perfectly balanced. Studies show that power control errors as small as 1 dB can reduce actual channel capacity by 20 percent. We know that over a mobile vehicle transceiver’s lifetime, many sources of power measurement error and power control error will accumulate to levels beyond 1 dB.
The original CDMA technique of trying to precisely balance power no longer provides optimum performance. Our MUD implementation eliminates the need for super-accurate power control. Until recently, processors powerful enough to run the very complex MUD algorithm chosen by Comtech were not available. However, our robust hardware platform design now provides the computational power required for near-real-time MUD signal processing at a very reasonable price point. ♦
