OK, so let's try to understand what the hell happened during the Endorian assault, because it is actually very odd that with a triumphant arrival at such a huge distance from their target, the Rebels would be surprised to notice that they were being jammed hard.
(in the novelization I think a fighter fails to break hard enough and crashes into the shield, so it seems to be like a wall)LANDO
We've got to be able to get some kind of a
reading on that shield, up or down. Well, how
could they be jamming us if they don't know
if we're coming.
Lando shoots a concerned look out at the approaching Death Star
as the implications of what he's just said sink in. He hits a
switch on his comlink.
LANDO
Break off the attack! The shield is still up.
RED LEADER (VO)
I get no reading. Are you sure?
LANDO
Pull up! All craft pull up!
The Falcon turns hard to the left. Out the window the stars and
the Death Star move off right.
96 EXT SPACE - DEATH STAR SHIELD 96
The Falcon and the fighters of Red Squad veer off desperately to
avoid the unseen wall.
97 INT REBEL STAR CRUISER - BRIDGE 97
Alarms are screaming and lights flashing as the huge ship changes
course abruptly. Other ships in the fleet shoot by outside as the
armada tries to halt its forward momentum.
ACKBAR
Take evasive action! Green Group, stick close
to holding sector MV-7.
A Mon Calamari controller turns away from his screen and calls
out to Ackbar, quite excited. The Admiral rushes over to the
controller.
CONTROLLER
Admiral, we have enemy ships in sector 47.
On the screen can be seen the moon, Death Star, and the massive
Imperial fleet. Ackbar moves to the comlink.
ACKBAR
It's a trap!
So, first of all, I think it's possible Rebel Command expected some global jamming a few moments after they'd come out of hyperspace, but perhaps nothing too dramatic. Their communications remained clean nonetheless. Although they seemed to be equally clean despite the vaunted "jamming" ship (the Praetor thing EUphiles talk about, but I don't think there's anything backing this up in pure canon).
However, it appears it takes some specific equipment for powerful jamming to be applied, and an entire fleet had to be jammed there, at a great distance at first.
With the DS incomplete, let's say the Rebels didn't expect any such system to be present, or powerful enough to take care of an entire assault fleet.
Now, as they near the Death Star, they keep scanning it, especially looking for any trace of shielding, and all seems normal until they get very close and realize they're being jammed.
They don't say the shield is masked from their sensors. They say they're being jammed, as directly affected by an active counter system that shoots crap at them.
Meaning that the Death Star was using an active system that directly acted on the sensors and fooled them by making them think that nothing was there.
This is quite tricky, because firing radiations at something is the surest way to be spotted.
So not only the Rebels couldn't see any jamming pattern on their sensors, but everything seemed normal, like in empty space, until they were too close.
That's some super sauce jamming, guys.
A theory might be that as the shield might emit some radiations at a given frequency, either passively or in return from active scanning; so the Death Star fired something that nullified those radiations.
- Super exotic : it radiated something that "ate" (reacted with) the shield's radiated particles. The result of that combination either sufficiently erased the trace of shield radiations, or transformed them into a mundane-looking enough form of radiation (perhaps after a particle cascading of some sort) that the Rebels would take for "vacuum noise".
- More normal : the Death Star fired "phased" radiations that matched the frequency and magnitude of the shield's radiation, so in the end it produced a more or less flatlined, near zero-sum residual radiation that would easily pass as mere vacuum noise.
All in all, only when getting close enough to the emitters one would start to see the two patterns and not just the resulting after effect/combination of both.
Dzatmeksns?
