5 ms·

Satellites, and surfacing to periscope depth (or enough to otherwise deploy an antenna) at predetermined, randomized and secret intervals?

sgt101 7y ago
Risky - home base would have to know, and you know what The Hell's Angels say about secrets...
pdonis 7y ago
The satellites don't have to know when the subs are going to come to antenna depth to receive messages. They just broadcast them continuously, and subs receive them when they decide to.
- mywittyname 7y ago
  An always broadcasting satellite may give away position.
  - ceejayoz 7y ago
    Of the satellite, not the sub, and that's not an issue.
  - chrisseaton 7y ago
    People know where satellites are anyway - you can literally see them in the sky. You can't hide them!
    - mywittyname 7y ago
      Obviously tracking an individual satellite would not provide you with any information, so I'm not sure why anyone would expect my comment to mean that. The major countries all have thousands of merchant vessels traveling in every major shipping lane all over the world. My thinking is navies would be worried about these ships being equipped with sensors that analyze satellite signals looking for what could be intended for submarine communication. Eaves droppers wouldn't even need to break the encryption of the signal, they'd only need to be aware of a signal is being broadcast to only a specific region of the the ocean and that bears other attributes associated with military communication.
      - ceejayoz 7y ago
        Simple solution: Don't broadcast to a specific region of the ocean. (HQ may not even know exactly where the sub is, so this is probably necessary anyways.)
        mywittyname 7y ago
        Or simplest solution: don't broadcast to them at all. Which was the point I was making as to the likely reason they don't do it. Broadcasting over a larger area reduces the ability of an adversary to infer location from the signal, but increases the likelihood of intercept. That alone might not be terribly useful, but it can be combined with other bits of information and form a more complete picture. For example, if you know when and where the sub was last docked, fleet movements, regional events that are of military interest, and you have a signal with a message you suspect was intended for them, then that's enough bits of information to be useful. There are trade-offs. If you're required to minimize the the likelihood of discovery at all costs, then it makes sense to never even attempt communication while underway.
        ceejayoz 7y ago
        It's common knowledge that we communicate with submarines. https://en.wikipedia.org/wiki/Communication_with_submarines https://en.wikipedia.org/wiki/Communication_with_submarines The article confirms this: > Salles said the situation now will be toughest for any crews that leave harbor in the weeks ahead, because they’ll know they are leaving loved ones in the midst of the pandemic and, possibly, still living in lockdown. The French government has already extended its stay-home orders once, to April 15, and said it could do so again. > Salles said he believes those crews will get regular coronavirus updates, but won’t be told of any family deaths until they are returning to the l’Ile Longue submarine base, near Brest in Brittany.
        pdonis 7y ago
        > you have a signal with a message you suspect was intended for them That would require you to be able to decrypt the encrypted signal that the satellite is broadcasting. Which you can't. All these third party observers see is a bunch of digital noise continuously being broadcast by the satellites. They have no way of telling digital noise destined for a particular sub from the rest of the digital noise. So the signals convey no useful information to them.

sgt101 7y ago

Risky - home base would have to know, and you know what The Hell's Angels say about secrets...

pdonis 7y ago

The satellites don't have to know when the subs are going to come to antenna depth to receive messages. They just broadcast them continuously, and subs receive them when they decide to.

mywittyname 7y ago
An always broadcasting satellite may give away position.
- ceejayoz 7y ago
  Of the satellite, not the sub, and that's not an issue.
- chrisseaton 7y ago
  People know where satellites are anyway - you can literally see them in the sky. You can't hide them!
  - mywittyname 7y ago
    Obviously tracking an individual satellite would not provide you with any information, so I'm not sure why anyone would expect my comment to mean that. The major countries all have thousands of merchant vessels traveling in every major shipping lane all over the world. My thinking is navies would be worried about these ships being equipped with sensors that analyze satellite signals looking for what could be intended for submarine communication. Eaves droppers wouldn't even need to break the encryption of the signal, they'd only need to be aware of a signal is being broadcast to only a specific region of the the ocean and that bears other attributes associated with military communication.
    - ceejayoz 7y ago
      Simple solution: Don't broadcast to a specific region of the ocean. (HQ may not even know exactly where the sub is, so this is probably necessary anyways.)
      - mywittyname 7y ago
        Or simplest solution: don't broadcast to them at all. Which was the point I was making as to the likely reason they don't do it. Broadcasting over a larger area reduces the ability of an adversary to infer location from the signal, but increases the likelihood of intercept. That alone might not be terribly useful, but it can be combined with other bits of information and form a more complete picture. For example, if you know when and where the sub was last docked, fleet movements, regional events that are of military interest, and you have a signal with a message you suspect was intended for them, then that's enough bits of information to be useful. There are trade-offs. If you're required to minimize the the likelihood of discovery at all costs, then it makes sense to never even attempt communication while underway.
        ceejayoz 7y ago
        It's common knowledge that we communicate with submarines. https://en.wikipedia.org/wiki/Communication_with_submarines https://en.wikipedia.org/wiki/Communication_with_submarines The article confirms this: > Salles said the situation now will be toughest for any crews that leave harbor in the weeks ahead, because they’ll know they are leaving loved ones in the midst of the pandemic and, possibly, still living in lockdown. The French government has already extended its stay-home orders once, to April 15, and said it could do so again. > Salles said he believes those crews will get regular coronavirus updates, but won’t be told of any family deaths until they are returning to the l’Ile Longue submarine base, near Brest in Brittany.
        pdonis 7y ago
        > you have a signal with a message you suspect was intended for them That would require you to be able to decrypt the encrypted signal that the satellite is broadcasting. Which you can't. All these third party observers see is a bunch of digital noise continuously being broadcast by the satellites. They have no way of telling digital noise destined for a particular sub from the rest of the digital noise. So the signals convey no useful information to them.