Segment Information (Details) (USD $)	3 Months Ended
	Oct. 31, 2013 operating_segment	Oct. 31, 2012 operating_segment	Jul. 31, 2013 operating_segment
Segment Reporting Information [Line Items]
Number of reportable operating segments	3	3	3
Net sales	$ 83,368,000	$ 90,953,000
Operating income (loss)	10,099,000	13,362,000
Interest income and other (expense)	273,000	276,000
Interest expense (income)	2,018,000	2,111,000
Depreciation and amortization	4,239,000	4,352,000
Expenditure for long-lived assets, including intangibles	1,027,000	1,063,000
Total assets	682,575,000	705,594,000	681,815,000
Benefit related to a change in fair value of contingent earn-out liability	239,000	2,378,000
Amortization of stock-based compensation	947,000	745,000
Telecommunications Transmission Segment [Member]
Segment Reporting Information [Line Items]
Net sales	54,365,000	53,327,000
Operating income (loss)	8,929,000	12,259,000
Interest income and other (expense)	6,000	(9,000)
Interest expense (income)	59,000	159,000
Depreciation and amortization	2,259,000	2,436,000
Expenditure for long-lived assets, including intangibles	933,000	841,000
Total assets	243,851,000	233,446,000
Benefit related to a change in fair value of contingent earn-out liability	239,000	2,378,000
RF Microwave Amplifiers Segment [Member]
Segment Reporting Information [Line Items]
Net sales	20,197,000	25,289,000
Operating income (loss)	591,000	1,718,000
Interest income and other (expense)	(5,000)	(22,000)
Interest expense (income)	0	0
Depreciation and amortization	943,000	980,000
Expenditure for long-lived assets, including intangibles	94,000	207,000
Total assets	92,774,000	95,785,000
Mobile Data Communications Segment
Segment Reporting Information [Line Items]
Net sales	8,806,000	12,337,000
Operating income (loss)	4,106,000	3,471,000
Interest income and other (expense)	3,000	9,000
Interest expense (income)	0	0
Depreciation and amortization	74,000	152,000
Expenditure for long-lived assets, including intangibles	0	15,000
Total assets	7,236,000	8,511,000
Restructuring charge related to the wind-down of microsatellite product line		822,000
Unallocated [Member]
Segment Reporting Information [Line Items]
Net sales	0	0
Operating income (loss)	(3,527,000)	(4,086,000)
Interest income and other (expense)	269,000	298,000
Interest expense (income)	1,959,000	1,952,000
Depreciation and amortization	963,000	784,000
Expenditure for long-lived assets, including intangibles	0	0
Total assets	338,714,000	367,852,000
Amortization of stock-based compensation	947,000	745,000
Telecommunications Transmission Sales to RF Microwave Amplifiers [Member]
Segment Reporting Information [Line Items]
Intersegment sales	301,000	1,234,000
Telecommunications Transmissions Sales to Mobile Data Communications [Member]
Segment Reporting Information [Line Items]
Intersegment sales		$ 2,507,000