To clear up a few questions that I've gotten or might get later on concerning various combat systems:

All military FRAMEs have, at the very least, radar and infrared/thermal senor packages, and smoke/chaff launchers. I'll go into a bit of detail about the operation of said equipment to help those "uninitiated" with their IC posts.

Radar works by bouncing radio waves off objects and receiving the signals to determine the bearing and range of said objects. FRAME radars are primarily for locating the position of other FRAMEs or military-grade vehicles. The received signal informs the pilot of the approximate location, size, bearing and range of whatever objects it comes into contact with. This information is displayed on a monitor in the cockpit. Radar alone doesn't typically differentiate between friend and foe, however, so additional visual confirmation about the nature of the objects is necessary to avoid friendly fire or other incident. Radars can paint a simplified image of a FRAME's immediate surroundings.

Specialized FRAMEs may make use of sonar, which operates similarly to radar. The difference is radar uses electromagnetic radio waves, and sonar uses sound waves. Both echo off objects and send data back to the source. Because it's an electronic system, radar is frequently jammed by ECM, which makes sonar a handy alternate for identifying and locating targets. Sonar packages will probably be added as a subsystem in the RP's context, in the form of a passive ground suite. Spikes inserted into the ground can pick up vibrations in the earth and send them to the pilot as audible information.

Thermal optics allow pilots to visually identify targets based on heat; FRAMEs and other military vehicles generate heat as they run, so it's an effective way to get an eye on a target. Infrared is a spectrum in which thermal radiation emissions can be seen. Objects that aren't hot enough to radiate visible light will emit infrared energy, which can be felt as heat. Hotter objects give off more infrared radiation. Chaff and smoke launchers can temporarily disrupt thermal optics if the smoke is laced with aluminum-coated glass fibers or red phosphorus. The emissions from the smoke and the material in it can hide emissions from objects behind it for a short length of time.

And now for a bit of fiction: The C3 suite subsystem sort of combines the sensors of multiple FRAMEs in a unit and clumps it into a cohesive picture. So a commander like Cecilia could look at her C3 monitor and see the radar and heat signatures of all her squadmates, and she can also use the system to see just what [i]their[/i] sensors are picking up. It constantly collects data being fed by allied machines and puts it into a visual map of the zone of operation. 
So Cpl. Jones might have an "oh, shit" moment and turn the corner to find a squad of mooks looking at him, and Lt. Brown's C3 will update him of the new data Jones' FRAME has picked up from the mooks. It's a nifty tool for commanders to [s]micromanage their grunts[/s] remain totally aware of updates to their surroundings and act accordingly.