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"...During one raid in southern Lebanon, Israeli special forces said they found a Hezbollah office equipped with jamming and eavesdropping devices. It was my impression that this kind of signal interception was really, really hard to do -- especially for an irregular force like Hezbollah. I know there are some radio and commsec gurus who read the site regularly. Weigh in here, guys. "

Ok, some short comments.

Jamming can be done by just about anyone who has access to an electronics store, some wire and power. The problem with jamming is that it gives your position away (at least the position of the transmitting antenna). This in turn, makes it a nice target. In short, not difficult... just not "wise" to do it often and at high power levels. Selective jamming takes a bit more common sense but is not that effective.

As for eavesdropping.... depends. A lot of people confuse signals interception and signals interpretation. In short, can you hear them (intercept) and can you understand them (interpret) are two different activities. Most often, when people say eavesdropping they are mixing the two terms.

Interception of frequency hopping signals is doable but often requires a bit of skill / luck / intelligence to track the hopping pattern. Once you know the pattern or can identify (interpret) a signal within the transmission, frequency hopping is not as effective of a signals defense. I should point out that a lot of non-signals people tend to not practice good transmission practices and this can lead to compromises in the overall security.

As for interpret, the fundamental protection against interpretation is encryption. Low levels of encryption can be broken by a few high powered machines in a few hours. This requires a bit more skill and knowledge and is normally thought to be outside of the range of a non-state sponsored terror cell. However, I believe it has been shown that the Hezzies are state sponsored and much stronger encryption should be employed.

My opinion is that following the frequency hopping is not that technically difficult and if weak encryption was used, then with the sponsorship of Iran, the Hezzies would have the capability to listen in. BTW, one of the warning signs that your encryption has been broken is when the other side stops or significantly reduces jamming efforts. You see, if they are jamming you, they can't listen in.

"My opinion is that following the frequency hopping is not that technically difficult and if weak encryption was used, then with the sponsorship of Iran, the Hezzies would have the capability to listen in. BTW, one of the warning signs that your encryption has been broken is when the other side stops or significantly reduces jamming efforts. You see, if they are jamming you, they can't listen in."

I agree. Frequency hopping is easily detected by common spectrum analyzers. Once detected, Direction Finding (DF'ing) the source of those freq-hop broadcasts is a well known tactic.

A stronger signal typically means that the transmitter (in this case, Israeli tanks) is moving closer. A weakening signal, moving further away.

It's not complicated.