Where "C" wrote on Nov 25, 2022 "I'm no sonar engineer, but I'm still baffled why a sonar system in passive mode would consume upwards of 75Kw - active is different for sure - those are BIG numbers."
I'm also no sound engineer,
but I would say:
A passive sonar uses a lot of
power to amplify very weak sounds and for massive processing of signal tasks to make sense of sounds, esoecially identifying the precise source. See what Aaron describes in 2 below.
SSKs and SSNs (all attack
subs) are more famous users of spherical active and passive sonar uses
for ASW and anti-ship work.
However attack subs also use
very weak, discrete beam, active/passive navigation/movement sonar
pulses to image the seafloor, seamounts and other obstructions that the sub
would otherwise risk banging into. Again these are very weak pulses
undetectable by enemy sonars/seafloor hydrophones but are received on a
constant basis by the sub's active/passive bow sonar.
1. On what happens when this imaging system doesn't work or
isn't efficiently used see my November 2021 reporting on the Seawolf class sub
USS Connecticut's major accident hitting a seamount:
1A -
here https://gentleseas.blogspot.com/2021/11/us-sub-did-hit-seabed-projecting.html
1B -
especially the diagram here https://gentleseas.blogspot.com/2021/11/uss-connecticuts-sonar-navigation-wasnt.html
2 Aaron, a former USN Los Angeles class SSN and Ohio class SSBN Sonarman, does discuss how sonars/sonarmen work in detail here and on his "Sub
Brief" Youtube website https://www.youtube.com/c/subbrief
Aaron's (aka Jive Turkey's)
description is interesting:
2A -
2min45secs into "The Ping" https://youtu.be/24uLeEKma5g It sounds like Aaron was using a great deal
of energy for his Active (anti-sub or surface ship) "Ping".
2B - 20min into "USS Connecticut South China Sea
Collision" https://youtu.be/5VKQPBhu0z0
eg. avoid collision "tools...that
they will not make public" which Pete suspects is navigation sonar mode.
2C - 1:36 into "USS Connecticut Damage Update..." https://youtu.be/vB-eSTpvKgs shows what I think is the half spherical active sonar - it is so positioned (mainly downward) to send weak navigation pulses, picked up by the much larger spherical passive sonar. (photo above)
So much for us all to learn on
the edges of guesswork.
5 comments:
Hi Pete
I concur with your points, certainly we are on the edge of guesswork, but some prior comments by other regulars filled in more blanks than I was expecting.
I'm still gobsmacked at the thought of 75Kw of amplification (that's one helluva rock concert), but I agree on the big SSN's like Seawolf/Virginia/Astute its quite possible. My gut still says these numbers reflect rather dated backend processing tech - the difference in solid state amplification and subsequent processing in a year 2000 or even 2005 system is chalk and cheese to today, which is literally orders of magnitude more capable on a per watt basis.
As you say though, the edge of guesswork, we wont know for years until this stuff becomes declassified.
I'm satisfied that it seems, on the basis of my calcs and other commenters that the core hotel load has remained in the 30-50Kw range, and that excess to this is essentially combat and sonar systems, and so we have a broad understanding of the composition.
C
Sir,
for the spanish S-80 you can find some info about Hotel & Propulsion power in the following official publication:
https://armada.defensa.gob.es/archivo/mardigitalrevistas/boletinetsian/2013/02btndiciembre2013.pdf
I am sure that it could be of general application for otrher modern SSK + AIPs
Pages 6 & 7, it is in spanish but "tables" and maths are universal...
Hi C @Nov 28, 2022, 9:52:00 AM
Armed still with guesswork, I suspect the high power combat system data processing needs of a US/UK SSN and also SSBN may involve almost instantaneous processing through
perhaps TeraBytes of data that 3D models (with overlays) many qualities of their ocean surrounds eg. temperature, salinity, magnetic anomaly, electrical activity, average sound wave travel (in water and above surface), radiological trace, light levels, sonic messages from seabed sensor arrays, etc
all to predict - is it unusual? and if so, is it a hostile submarine, friendly vessel, living creature or geological disturbance.
So Aaron's https://www.youtube.com/watch?v=24uLeEKma5g and https://www.thedrive.com/the-war-zone/35603/veteran-submariner-on-how-sonar-crews-tirelessly-hunt-enemies-they-cant-even-see give just a small part of what is possible.
Regards Pete
Hi Anonymous @Nov 28, 2022, 11:08:00 PM
Thanks for that information about Hotel and Propulsion loads in
https://armada.defensa.gob.es/archivo/mardigitalrevistas/boletinetsian/2013/02btndiciembre2013.pdf
pages 6 and 7.
Regards Pete
Hi Pete
Agree that the more processing you throw at a data-set the more information can be extracted - this is axiomatic in data science. As a general rule, this is a diminishing returns exercise, however, and so I wonder if commanders of, specifically, modern non-nuclear boats have a metaphorical knob they can turn to regulate applied processing power. IE another tactical trade-off consideration for command: "Do I crank up the processing and drain the batteries in short order, or turn it down until situation evolves?" This in turn varies with contexts such as transit, attack, trailing, information gathering etc etc. I'm sure this must be the case if the vast majority of a boats potential load-draw is with these systems, IE how much they use their various sonar and associated processing systems will have an impact on underwater endurance second only to high-speed manoeuvre, and the latter case is only used in extremis, making the prior the principal concern for routine effective electrical power-store usage.
C
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