Recent upgrades in hardware within the weapons systems of our submarines have been achieved through state of the art technology replacements. Significant among these upgrades has been a replacement of analog systems with digital. A major step of course was the digitizing of the BQQ-5 Sonar System followed by the conversion of the MK 113 mod 10 analog fire control system to MK 117 digital system. There have also been major advances in digitizing of ESM equipments throughout the Navy which have benefited the WLQ-4, 6, and 8 ESM receiver/analyzer systems. These are fully computerized and semi-automatic but lack advances into microchip techology. Submarine satellite commuinications have also benefited from digital advances ushered in by the Navy Fleet Satellite system. But satellite communications suffer from research and development lead time which keeps application forever about 10 years behind system deployment.
There are several reasons for this technological upgrading. Most significant is real-time data computation and increased system capacity. Additional advantages for digital vice analog technology are greater reliability, increased accuracy, ability to expand an installed system for multiplex operation, and the relative ease of system upgrading and modification as future technological advances are made. For next generation SSN sonar and fire control systems, microchip technology with increased miniaturization and even more rapid computing capability may show even more significant advantages than those realized today.
Certainly, increased signal processing is a major operational improvement which must be made if we are to improve system and platform capability.
If digital technology is so ideal for sonar, fire control and ESM, why not use it more in Communications and Command and Control? The rate of introduction of digital technology into all facets of submarine electronics has not been uniform, probably for several reasons. Submarine sonar, fire control and ESM equipment& have generally developed as unique submarine systems without uni versa! applications elsewhere in the navy. Most Navy-wide Communication and Command and Control equipment has been developed with multiple platforms in mind. They were thus treated differently in conceptual stages. This, of course, does not explain why digital technology is not used now, it merely describes why its use has been neglected until now. Morevover, most electronics engineers are quite familiar with analog technology; it’s what they learned in school and what they are comfortable with when called on to design new systems.
Are there other advantages of digital technology which make it an even better candidate for future systems — which have not yet been capitalized upon?
Several ideas come to mind which have immense potential to improve other submarine systems:
- The use of separately sensed “noise monitoring” or noise measuring circuits, where this data is subtracted from a signal plus noise circuit, holds great promise for receiving weak signals that are masked by electromagnetic interference. These noise measuring circuits involve complex calculations that only digital technology is capable of handling in a real-time environment.
- Once digitized, signals can be stored in shift registers and simultaneously processed — the processing outputs applied to the (stored) data from which they were derived. This provides truly “simultaneous” response to changing signal environments. (In simple language, digitized communications are virtually unaffected by atmospheric disturbances, have an increased security in transmission, and can be received with far greater speed and accuracy.)
- Extra functional components can be used within a circuit card, where certain devices have a high failure rate but have built-in spares which can be switched to when a component fails. This can greatly increase reliability — resulting in a “no fail during lifetime” capability within a system .
- Increased resistance to heat, vibration and power supply failures is also essential for lifetime reliability.
Digital technology appears amenable to building a new system (with proper initial design) in such a way that future technology advances can later be made by card or module change-out to the same equipment — or by software changes within the existing equipment. It has already become apparent that much of the cost involved in a future system is its integration cost within its platform. Improved design, using digital system engineering, can however result in evolutionary upgrades at significantly less cost than for wholesale replacements.
What does all this mean in the world of submarine systems?
First, we need to look closely at all submarine electronic systems for next generation equipment and actively weigh the pros and cons of digital in each equipment. Certainly, communications equipment with the added requirement for cryptographic coverage should be identified for digital switchover. The capabilities and capacities of most ESM equipment would also be greatly improved with upgraded digital technology.
Next generation equipment needs to: be more responsive to technology advances; more reliable in operation; and demonstrate greater speed and capacity. Digital technology may well be the way to· get there.