Lets say I have a space fleet flying to attack an installation. The enemy knows I'm coming but not my numbers or exact disposition. Since I'm moving much slower then C the light from my fleet will race ahead of me and they will be able to see me coming, and my disposition and numbers, well in advance of my arrival.
To prevent this I want to throw up some 'electronic camouflage'. Start creating a massive amount of electronic radiation, in random chaotic patterns. The idea is to create so much 'white noise' that they can't make out my fleet and it's units through all the noise. They will still know I'm coming, but not what I bring with me.
How much energy expenditure would it require to throw up sufficient noise to hide the fleet from passive scanners, assuming the enemy has scanners for all major frequencies (I'm not just blocking visible light)? Is it a viable method of hiding my fleets units? if so how hard is it to create a radius much larger then my fleet requires, to further hide size and exact attack angle? How close can I get before it starts to get easier to make out what the enemy is seeing, and are there any obvious protections against the strategy?