Captain Patton is a retired submarine officer who is a frequent contributor to THE SUBMARINE REVIEW.
The nearly half-century Cold War was arguably won by NATO because the U.S. Submarine Force held a 40 dB (a 10,000 to 1 ratio) acoustic advantage over Soviet Submarines. As identified by author Tom Stefanick in Strategic Antisubmarine Warefare and Naval Strategy, this put the Soviet “Strategic Nuclear Reserve” – their deployed SSBNs-totally at risk, while the U.S. SSBN counterparts remained essentially invulnerable. Because of this detectability mismatch, U.S. SSBNs were able to use the increased ranges of improved missiles to employ even more of open ocean in which to conduct their patrols, further complicating any search attempts by Soviet SSNs, while Soviet SSBNs were forced to employ increased missile ranges by pulling further back into home waters where they created a target-rich enviro11me11t for U.S. SSNs.
In the new strategic environment, the SSBN is still an important player in the sense that a strong and secure nuclear deterrent will be required as long as weapons of mass destruction are still held by other entities, and acoustic advantage remains an important metric. However, there is also a new and perhaps equally important measure of effectiveness-that of a submarine’s Connectivity Advantage, be it pertaining to an SSBN, SSN, SSG, SSK or Air-Independent Propulsion (AIP) SSP.
At first blush, one might assume that connectivity advantage is entirely a function of available bandwidth-a simple but entirely wrong assumption. In returning to first principles, the goodness of all naval communications is a function of the following:
- Ubiquitous – global coverage
- Capability (for submarines -adequate capacity)
- Quickness (for submarines -fast enough)
- Timeliness (for submarines -soon enough)
While the first four items above are self-explanatory and apply universally to all naval platforms, the italicized reclamas to the last three highlight the exceptional nature of submarine connectivity which must be understood and exploited if connectivity advantage is to achieved and maintained-even under modern combat duress, where many connectivity options could be degraded or totally eliminated.
More so than any other community with the exception of Special Operating Forces (SOF), submariners realize that it is not so much the diameter of the comms pipe (bandwidth) that matters, but rather the time-bandwidth product-the volume of information that flows through that pipe. Higher bandwidths are still much appreciated by those communities, for that means that the same volume of information can be passed using a smaller dimension of time. Obviously, a key to keeping this time-bandwidth product small is to package the information as tightly as possible, leaving little or no room for adjectives, adverbs and other extraneous material. Please, thank you, save the “Happy Navy Day” messages from the Secretary of the Navy for us to read when we get back to port, rather than adding them to the broadcast.
All other things being equal (really a poor phrase, since they seldom are), quicker is better for transmission (or reception) of necessary information for SOF and submarines because of considerations of stealth and restrictions on mobility. In fact, there is room in the scheme of things where timeliness (to be discussed next) is traded off for quickness when a half hour is spent preparing a piece of information that is then transmitted in a few milliseconds. This trade-off is justified in that the half-hour plus a few milliseconds is quick enough for the process or situation at issue, and the same attention to detail as above in minimizing the total package size is an important element of the process.
Other situations exist where the receipt of information by the submarine needs to begin almost as soon as the originator authorizes its transmission, but it is permissible that the time taken for receipt of all of the even very simplest of messages can take some time. A classic example of this would be a 3-symbol alphanumeric code directing weapons release by an SSBN that could take 10 or so minutes to copy via Extremely Low Frequency (ELF). This time required for receipt can still be classified as near real time since it is quicker than the time it would take to make the rest of the ship’s systems ready to launch.
In fact, a holy grail of submarine connectivity would be the ability to tell a transiting submarine, anywhere in the world, who wasn’t due to copy the sked for another 12 hours, that there was an urgent need for him to establish a better communications stance as soon as possible, even if that action took 20-30 minutes.
Connectivity Advantage versus Submarine Type
It might seem from some of the references above that a sub-marine connectivity advantage benefits most high end nuclear-powered submarines. Counter intuitively, just the opposite is true. The less ability a submarine platform has to reposition itself quickly, or the less extra electricity it has to power sensors and to support onboard computer power to process and exploit their data, the more that platform benefits from superior connectivity-particularly as the recipient of pertinent tactical intelligence and targeting data. High-end platforms can often find themselves more the suppliers of tactical information to the grid than as users of information from that same grid.
Submarining Culture as a Vital Component of the Co1111ectivity Advantage
There are two distinct segments of a proper submarine culture as it pertains to connectivity. Commanding Officers (COs) must understand and share the broad operational concepts of his masters ashore to include knowing when those masters would not only approve, but expect him to deviate from the norm in executing a mission without asking for permission, and those masters ashore must have the confidence (and patience) to assume that their COs are operating in the best interests of the Queen in the absence of reassuring messages that confirm that. An important mantra of a successful Submarine Force is that “The COs will tell you something when they have something to say”.
Persistent, Passive, Low Data Rate Connectivity
A big deal was made in several paragraphs above of the desirability to keep unnecessary or redundant information or data from jilling an available comms pipe. In the best tradition of the wisdom that there is an exception to any rule, there is an important exception in this case which contributes markedly to a connectivity advantage for submarines.
If connectivity can be described as either persistent or non-persistent, and either passive (receive only) or active (two-way), and also either high or low data rate (like pornography, you know it when you see it), the mode of the 23 -8 thus possible combina-tions which enabled the reliable and survivable nuclear deterrent mentioned in the first paragraph was the Persistent, Passive, Low Data Rate (PPL) option. In this PPL option, the submarines while in an alert status were receiving, via a Buoyant Wire Antenna (BWA) or a towed buoy, a continuously stream of encrypted data and information only a tiny percentage of which was of tactical or strategic significance, and most of which was news, ball scores and familygrams from loved ones. The purpose of intentionally filling this pipe was to insure that there would be no strategic warning to potential adversaries given by a circuit of this sort coming up.
The Holy Grail of submarine connectivity for SSNs, SSGs, SSKs and SSPs would be the same PPL that SSBNs enjoy but while operating at tactically meaningful depths and speeds. It is available at slower speeds and shallower depths if the platfonn is equipped with a good BW A installation-either internally or, on smaller boats, externally mounted. A Program of Record for the US Navy has been the “Comms at Speed and Depth” (CSD) program with the goal of expanding that part of the speed/depth envelope available for some fonn of connectivity.
As surface warships are put more and more at risk from ground, air, surface warship and submarine- launched Anti-Ship Cruise Missiles (ASCMs), and in some cases, purported Anti-Ship Ballistic Missiles (ASBMs); and as aircraft face more and more capable, long-range Surface to Air Missiles (SAMs), the burden falls increasingly upon submarines to conduct offensive operations against targets of value ashore, and for other submarines to attempt to prevent them from doing so. In this head-on-head confrontation, it is unlikely that an acoustic advantage will carry the day as it did in the last half of the 20th century, since all modern submarines at slow speeds are virtually incapable of detecting one another at more than ranges expressed in shiplengths, but rather it will be which force has connectivity which is more reliable, robust, flexible and ubiquitous, and has adequate capacity, is fast enough and conveys infonnation soon enough.