OK KZT: What's wrong with AAC?

tlb wrote:To be clear, I am not talking about creating a jamming signal; rather how jamming might be minimized.

There are lots of techniques to defeat jamming. The simplest one is to simply have a stronger signal so the noise (jamming) is too low. Angular separation is also easy: use lasers. You can't jam lasers; you could at best saturate the receiver by shining a brighter light on it (like trying to read a laser with the sun as a background), but that still requires a very narrow cone and thus a platform in-between the sender and receiver.

One that can apply to omnidirectional signals we've known for nearly 40 years is spread spectrum: you spread out your signal over a much larger bandwidth. Using some techniques I'm not going to go into detail about (because I really don't remember the maths of), you transform the low-power spread signal into a narrow high-power signal, while simultaneously spreading any narrow interference over a large bandwidth, reducing its power. To jam such a SS signal, you need to jam the entire bandwidth, which requires much more power.

SS was initially a military secret, one that the US shared with the UK, so it was used very effectively during the Falklands War. The Argentines could neither jam RN transmissions nor even tell that transmissions were occurring (or at least that's what my professor said). SS was later declassified and was the basis of 2G CDMA cell phone networks (not the TDMA and GSM ones) and all of the 3G ones.

ThinksMarkedly wrote:There are lots of techniques to defeat jamming. The simplest one is to simply have a stronger signal so the noise (jamming) is too low. Angular separation is also easy: use lasers. You can't jam lasers; you could at best saturate the receiver by shining a brighter light on it (like trying to read a laser with the sun as a background), but that still requires a very narrow cone and thus a platform in-between the sender and receiver.

Also, in atmosphere, you could block laser transmissions by say firing smoke rounds -- but not only do you need to get those between the transmitter and receiver but you need to maintain sufficient concentration to scatter or block the laser.
And what's possible do with with a barrage of smoke rounds on Earth (assuming the wind isn't too high) would be impractical in space both because the vacuum would tend to make your obscurant disperse too quickly but also because everything's moving at significant speeds and would simply orbit or fly clear of your "smokescreen" analog in short order. (And that's especially true of Honorverse ships which are accelerating at hundreds of gees during combat)

I still think a MAlign platform can get close enough to jam at launch. People keep pointing out that such a ridiculously close platform will be localized in short order. Perhaps. Maybe. But it won't matter if the platform jams an entire launch by overloading its components. Fry the circuitry. It is okay if the platform is lost after it disables an entire launch. An LD and its crew are much more valuable than a platform.

Also, textev talks about the missiles from both combatants interpenetrating one another, like what happened with barricade. If a jamming platform interpenetrates a launch it could fry the links between the ACM and its brood. Perhaps even the sensors too.

ThinksMarkedly wrote:There are lots of techniques to defeat jamming. The simplest one is to simply have a stronger signal so the noise (jamming) is too low. Angular separation is also easy: use lasers. You can't jam lasers; you could at best saturate the receiver by shining a brighter light on it (like trying to read a laser with the sun as a background), but that still requires a very narrow cone and thus a platform in-between the sender and receiver.

Well, you could do that is missiles are controlled by lasers. At the typical ranges in the Honorverse the beam width will cover the entire launching fleet and you can use a much bigger laser than a missile can have.

cthia wrote:I still think a MAlign platform can get close enough to jam at launch. People keep pointing out that such a ridiculously close platform will be localized in short order. Perhaps. Maybe. But it won't matter if the platform jams an entire launch by overloading its components. Fry the circuitry.

You know my position. I'm not going to continue arguing this.

It is okay if the platform is lost after it disables an entire launch. An LD and its crew are much more valuable than a platform.

Agreed. The problem though is that it doesn't stop the second launch.

Also, textev talks about the missiles from both combatants interpenetrating one another, like what happened with barricade. If a jamming platform interpenetrates a launch it could fry the links between the ACM and its brood. Perhaps even the sensors too.

You're proposing to fry the ACMs -- it would be easier to simply shoot them -- before they reach their own attack range, so they can't coordinate the attack. That's fair. The Cataphract is a CM on the end of a regular missile anyway, so shooting another missile on the way would be part and parcel of what it's supposed to do. The ACMs are also very clearly separated from the rest, so identifying them should be relatively easy.

Of course, this is a technique that would work only once. The moment it's used, the next salvos would be programmed to fly like regular missiles until arriving near the CM interception basket. This would degrade their long-range performance a little, but if they're still under FTL or even light-speed control, it's not going to be an issue. Plus, the oncoming missiles are highly visible, so the motherships could easily program them to disperse and (pseudo-) randomise locations, then once through resume Apollo flying formation.

Or just fly an arc away from the other missiles. Unlike non-Apollo launches, they're not going to get lost (not that I think non-Apollo launches would, but Apollos definitely wouldn't). That might not be particularly easy, because it's a game of cat and mouse.

A third option is to simply detonate some Dazzlers during the interpenetration. The accuracy of CMs can't be very good from that far away from their home vessels. And Dazzlers are supposed to confuse full ships -- a few autonomous missiles would be child's play for them.

ThinksMarkedly wrote:

tlb wrote:To be clear, I am not talking about creating a jamming signal; rather how jamming might be minimized.

There are lots of techniques to defeat jamming. The simplest one is to simply have a stronger signal so the noise (jamming) is too low. Angular separation is also easy: use lasers. You can't jam lasers; you could at best saturate the receiver by shining a brighter light on it (like trying to read a laser with the sun as a background), but that still requires a very narrow cone and thus a platform in-between the sender and receiver.

One that can apply to omnidirectional signals we've known for nearly 40 years is spread spectrum: you spread out your signal over a much larger bandwidth. Using some techniques I'm not going to go into detail about (because I really don't remember the maths of), you transform the low-power spread signal into a narrow high-power signal, while simultaneously spreading any narrow interference over a large bandwidth, reducing its power. To jam such a SS signal, you need to jam the entire bandwidth, which requires much more power.

SS was initially a military secret, one that the US shared with the UK, so it was used very effectively during the Falklands War. The Argentines could neither jam RN transmissions nor even tell that transmissions were occurring (or at least that's what my professor said). SS was later declassified and was the basis of 2G CDMA cell phone networks (not the TDMA and GSM ones) and all of the 3G ones.

interesting side note:
Hedley Lamar (The 30/40s blond Bombshell actress) was the inventor of Spread Spectrum - she developed a system using 88 frequencies to frequency jump torpedo control channels to make them unjamable. Pretty much it was an advanced version of the player piano tied to a radio with the 88 frequencies - the torpedo and controller started their "roll" simultaneously and both would flip frequencies in sync. The Navy ignored it for >10 years and started work with it in the late 50's.

Theemile wrote:interesting side note:
Hedley Lamar (The 30/40s blond Bombshell actress) was the inventor of Spread Spectrum - she developed a system using 88 frequencies to frequency jump torpedo control channels to make them unjamable. Pretty much it was an advanced version of the player piano tied to a radio with the 88 frequencies - the torpedo and controller started their "roll" simultaneously and both would flip frequencies in sync. The Navy ignored it for >10 years and started work with it in the late 50's.

Indeed, but that's FHSS - Frequency Hopping Spread Spectrum. And that can defeat jamming if the enemy can't blanked out all the frequencies or predict which one it'll jump next to. The secret of FHSS is that both sender and receiver have a pseudorandom sequence they both follow, but an outside party can't know. This is also a method of encryption through obscurity: if you don't know which order to read the frequencies, you can't read it. But the data is there, in the clear, unless another encryption mechanism is applied.

The one that the Falklands War and later CDMA networks used and I described is a much more complex version called DSSS - Direct Sequence Spread Spectrum. It still involves a shared secret, but that secret isn't used to choose a frequency. In DSSS, the transmission remains in a single frequency, but each chunk of bits of the original transmission (the symbol) is transformed into a very long digital signal and forms the "chip". It's also an encryption mechanism: without this shared secret -- or at least its length -- even if you intercept the entire band and know the modulation forms, it's all noise.

Of course, you can also do both of them.

tlb wrote:

Loren Pechtel wrote:About that. The number of incoming birds has little to do with how many get picked off. If anything more birds mean more EW jamming and fewer birds picked off.

Are you saying fewer in total number or fewer as a percentage of the total? I would expect the total number destroyed will increase as the number of missiles increases, up to some point where the defense is saturated. Below that saturation point I expect the percentage destroyed to slowly decrease as the number of missiles increases. Yes, there are more electronic counter measures, but there are also more missiles to shoot.

And that's where we disagree. I think that up to the point of saturation few birds will get through. Beyond that point most birds will get through. The number intercepted will go up somewhat as once you're past saturation every inbound gets engaged only once, there's no issue of evaluating whether another shot is needed.

Jonathan_S wrote:So not impossible to overfly a ship and fire back at it. But you'd have to set up that approach a long way back to ensure you were on a vector that let you see the ship to make that snap over the shoulder shot before you were back out of laserhead range. And you'd need to pass all the way through its CM zone on the way in - even if you found a vector that used your own wedge to protect you from its PDLCs until you'd overflown it.
(And even then, its PDLCs might kill you as you tried to make the over the shoulder shot -- just like we've seen them sometimes successfully engage missiles just clearing the lip of the wedge when the ship had rolled behind its wedge against the strike.

I think firing back at ships will be normal behavior. Consider an incoming missile vs the plane of the wedge of the target ship. To actually hit the ship the missile must detonate when it's vector passes through the plane of the wedge. If the defenders have rolled their wedges there is almost a 50% chance that this point is after overflying the ship.

cthia wrote:Agreed. However, the missile in a wet navy sub is locked on from the moment of launch. An HV missile is not locked on from the moment it is fired. It is being guided. An HV missile continues to need guidance until the sensors of the missiles are in range of the targets.

I don't see how those links can survive being cut early, especially when maneuvering targets are fully aware that the missiles are flying blind, and when they began to fly blind.

No--wet-navy missiles and torpedoes are no more locked on that Honorverse navy missiles. The seeker heads simply don't have that kind of range.

Older heat-seeking and passive radar-guided missiles had to be locked on from launch, but that does not apply to the latest stuff--even the heat seekers can fly to a location and go active. (This lets you do an off-axis shot.)