Cost Reduction Actions (Details) (USD $)
 1 Months Ended 3 Months Ended 9 Months Ended 30 Months Ended
Aug. 31, 2009
Apr. 30, 2011
Apr. 30, 2010
Oct. 31, 2008
Apr. 30, 2011
Apr. 30, 2010
Apr. 30, 2011
Cost Reduction Actions              
Proceeds from sale of a small product line $ 2,038,000            
Business acquisition restructuring costs, total estimated costs       2,713,000      
Business acquisition restructuring costs related to severance for employees       613,000      
Total non-cancelable lease obligations       12,741,000      
Less: Estimated sublease income       (8,600,000)      
Total net estimated facility-related exit costs   4,073,000   4,141,000 4,073,000   4,073,000
Less: Interest expense to be accreted       (2,041,000)      
Present value of estimated facility-related exit costs   2,420,000   2,100,000 2,420,000   2,420,000
Radyne lease expiration date Oct. 31, 2018
Radyne sublease expiration date Oct. 31, 2015
Present value of estimated facility-related exit costs, beginning balance       2,100,000 2,136,000   2,100,000
Cash payments made         (736,000)   (3,050,000)
Cash payments received         901,000   2,982,000
Interest accreted on the facility-related exit costs   41,000 34,000   119,000 113,000 388,000
Present value of estimated facility-related exit costs, ending balance   2,420,000   2,100,000 2,420,000   2,420,000
Amount of facility-related exit cost liability recorded as prepaid expenses   395,000     395,000   395,000
Facility-related exit cost liability, Noncurrent   2,815,000     2,815,000   2,815,000
Less expected net cash to be received in next twelve months   (395,000)     (395,000)   (395,000)
Interest expense to be accreted in future periods   $ 1,653,000     $ 1,653,000   $ 1,653,000