Segment Information (Details) (USD $)	3 Months Ended		9 Months Ended		12 Months Ended
	Apr. 30, 2013	Apr. 30, 2012	Apr. 30, 2013	Apr. 30, 2012	Jul. 31, 2012
Segment Reporting Information [Line Items]
Number of reportable operating segments	3		3		3
Net sales	$ 69,856,000	$ 99,793,000	$ 235,386,000	$ 312,295,000
Operating income (loss)	5,391,000	10,566,000	24,700,000	36,979,000
Interest income and other (expense)	287,000	370,000	878,000	1,300,000
Interest expense (income)	2,009,000	2,192,000	6,150,000	6,521,000
Depreciation and amortization	4,216,000	4,873,000	12,950,000	14,974,000
Expenditure for long-lived assets, including intangibles	1,560,000	1,807,000	4,017,000	4,467,000
Total assets	676,362,000	746,360,000	676,362,000	746,360,000	719,778,000
Benefit related to a change in fair value of contingent earn-out liability			3,267,000	844,000
Amortization of stock-based compensation	694,000	809,000	2,245,000	2,718,000
Telecommunications Transmission Segment [Member]
Segment Reporting Information [Line Items]
Net sales	45,410,000	48,044,000	144,506,000	156,168,000
Operating income (loss)	6,261,000	8,463,000	24,069,000	29,816,000
Interest income and other (expense)	(2,000)	15,000	(37,000)	35,000
Interest expense (income)	55,000	163,000	294,000	495,000
Depreciation and amortization	2,378,000	2,530,000	7,241,000	7,604,000
Expenditure for long-lived assets, including intangibles	1,359,000	1,581,000	3,428,000	3,651,000
Total assets	227,138,000	244,208,000	227,138,000	244,208,000
Benefit related to a change in fair value of contingent earn-out liability	0	844,000	3,267,000	844,000
RF Microwave Amplifiers Segment [Member]
Segment Reporting Information [Line Items]
Net sales	16,169,000	28,111,000	61,820,000	71,661,000	102,497,000
Operating income (loss)	(121,000)	2,587,000	2,242,000	4,105,000
Interest income and other (expense)	(10,000)	9,000	(39,000)	3,000
Interest expense (income)	0	0	0	0
Depreciation and amortization	984,000	1,121,000	2,941,000	3,325,000
Expenditure for long-lived assets, including intangibles	130,000	155,000	472,000	630,000
Total assets	94,832,000	102,816,000	94,832,000	102,816,000
Mobile Data Communications Segment [Member]
Segment Reporting Information [Line Items]
Net sales	8,277,000	23,638,000	29,060,000	84,466,000
Operating income (loss)	2,434,000	2,638,000	8,899,000	16,409,000
Interest income and other (expense)	3,000	7,000	15,000	23,000
Interest expense (income)	0	0	(6,000)	0
Depreciation and amortization	125,000	366,000	411,000	1,183,000
Expenditure for long-lived assets, including intangibles	71,000	71,000	112,000	186,000
Total assets	13,780,000	37,203,000	13,780,000	37,203,000
Restructuring charge related to the wind-down of microsatellite product line	0	0	569,000	0
Unallocated [Member]
Segment Reporting Information [Line Items]
Net sales	0	0	0	0
Operating income (loss)	(3,183,000)	(3,122,000)	(10,510,000)	(13,351,000)
Interest income and other (expense)	296,000	339,000	939,000	1,239,000
Interest expense (income)	1,954,000	2,029,000	5,862,000	6,026,000
Depreciation and amortization	729,000	856,000	2,357,000	2,862,000
Expenditure for long-lived assets, including intangibles	0	0	5,000	0
Total assets	340,612,000	362,133,000	340,612,000	362,133,000
Costs related to a withdrawn contested proxy solicitation				2,638,000
Amortization of stock-based compensation	694,000	809,000	2,245,000	2,718,000
Telecommunications Transmission Sales to RF Microwave Amplifiers [Member]
Segment Reporting Information [Line Items]
Intersegment sales	361,000	1,333,000	2,018,000	3,032,000
Telecommunications Transmissions Sales to Mobile Data Communications [Member]
Segment Reporting Information [Line Items]
Intersegment sales	$ 18,000	$ 1,047,000	$ 2,637,000	$ 5,937,000