B-2 requires $1B radar upgrade, page 1
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reply posted on 26-3-2009 @ 04:26 PM by Zaphod58
reply to post by neformore



This is the first radar system that I've heard of this happening to. One of the reasons that it's so bad is that the stealth radars jump around frequencies so much to avoid detection, so that makes it harder to keep bandwidths clear.

One of the interesting things in the second article was that if two or more F-35s are flying at the same time, nothing else in the Western US could be flying. And this is after they "fixed" the bandwidth problem with them.



reply posted on 26-3-2009 @ 04:41 PM by BASSPLYR
Zaphod58,

You know all about this sort of stuff and I figured I should ask you a few questions.
But before I do let it be known that I know very little about radar, especially in the circumstances the article is talking about regarding the B2. The article is a eye opener for me since it educated me about a lot I didn't know about radar. but here's my confusion.

The bandwidth. I figured that radar used specific bandwidths, but I always assumed that the bandwidth could be modulated or changed so the radar would be more adaptive to unforeseen contingencies or even foreseen ones. I was surprised to find out that the bandwidth the radar used could even be available to the civilian sector let alone to most military sectors. Let alone that event interfering majorly with the radars operation.

If the radar uses only one bandwidth wouldn't it be very easy to track the aircraft when it's using it's radar by using maybe even passive arrays to detect that specific radar frequency?

Is the broadcasting of radar from a source outside the B2 on the same bandwidth the B2 is using basically the same thing as flooding a room with infrared light to blind a night vision camera?

Please help me get a grasp on what the article is discussing. I'm sorta not following the logistics of the problem entirely. Due to my lack of knowledge regarding radars applications for navigation or detection. I get the general principles but not the details, as I'm a little naive to them.

Thanks,

Bassplyr.


reply posted on 26-3-2009 @ 06:46 PM by Zaphod58
reply to post by BASSPLYR



Ah, but that's the kicker. Raytheon already had a contract to upgrade the radar to AESA on all the B-2s. But they had to stop, and alter them all because of the bandwidth sale. They had the new sets on 6 aircraft if I remember correctly, flight testing them.


reply posted on 26-3-2009 @ 07:04 PM by Zaphod58
reply to post by BASSPLYR



That is a good question. I doubt that you'll be able to find much information out there about the way the radar works.

About all I know about the new system is that it's not changing the processing or signal, or any new capabilities, but it does lay the foundation for future growth. They have two antennas mounted in the leading edges, and use the radar for weather, aircraft deconfliction, tanker rendezvous, and station keeping.

The B-2 is fitted with an AN/APQ-181 radar, with some similarities to the AN/APG-70 used on the F-15E Strike Eagle fighter. The AN/APQ-181 is a Ku band (high microwave, from 12 GHz / 3 centimeters to 18 GHz / 2 centimeters) radar, with an electronically steered antenna in the lower leading edge of each wing. The Ku band suffers from greater atmospheric attenuation than lower frequency bands, but it also provides very high resolution for navigation and targeting.

The AN/APQ-181 provides "low probability of intercept (LPI)" operation, with the radar dancing over frequencies and changing pulse patterns so that its signals can't be picked out of background noise until it's too late. Apparently the TACIT BLUE program did much to advance LPI radar technology; it would have made absolutely no sense to design a stealthy battlefield surveillance aircraft and then have it announce its presence by blasting out strong and easily detected radar signals. The AN/APQ-181 provides 20 operational modes, including a "Synthetic Aperture Radar (SAR)" mode for ground mapping, with a "Ground Moving Target Indicator (GMTI)" capability; a "Terrain Following / Terrain Avoidance (TF/TA)" mode for low-level flight; a mode for spotting and linking up with a tanker; and weather mapping and navigation modes.

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