Fool the Street once, shame on you. Fool it twice . and professional investors get worried. Fool it more than that, and you've got a problem. And with four straight sizable quarterly misses, AppliedSignal Technology (NASDAQ:APSG) definitely has a problem.

In its fiscal third quarter, this digital processing technology provider for the intelligence community once again missed the bull's eye that the analysts painted. Sales fell by about 5% compared with last year to just above $36 million, while operating income and earnings per share were basically cut in half. In relation to analyst expectations, the company missed by about 10% on the top line and 35% (or $0.08) on the bottom line.

It's good and bad news alike for Applied Signal that the company is virtually 100% focused on the so-called C4ISR market (that's command, control, communications, computers, intelligence, surveillance, and reconnaissance), and the U.S. government is pretty much its only customer. When the government drags its feet with new orders or hesitates to define the parameters of a contract, there's not much the company can do to pump up the business.

The big long-term question for Applied Signal, then, is how sincere the government really is about upgrading its capacity to eavesdrop on potential wrongdoers. Taxpayers will pay only so much for their own defense, and the government has to portion out money for its military actions in Afghanistan and Iraq as well as for upgraded homeland security efforts. And, of course, there are other critters at the trough. Larger companies such as L-3Communications (NYSE:LLL), Boeing (NYSE:BA), Lockheed (NYSE:LMT), and NorthrupGrumman (NYSE:NOC) will all fight for their piece of the pie as well.

Applied Signal certainly has some things going right for it. Its balance sheet is pretty clean, and the company has top-notch technology for in-demand applications. That said, once a company starts missing estimates, the odds point to ongoing problems -- as four straight quarterly misses might suggest.

It's true that the company is only a couple of big contract announcements away from seeing the stock (and, hopefully, the business) recover. But it's equally true that one-market/one-customer companies have a higher-than-average risk to them. For me, I'd rather wait to see more of a discount before I tune into this particular signal.

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Fool contributor Stephen Simpson has no financial interest in any stocks mentioned (that means he's neither long nor short the shares).