Segment Information (Details) (USD $)	3 Months Ended		6 Months Ended
	Jan. 31, 2012 segments	Jan. 31, 2011	Jan. 31, 2012 segments	Jan. 31, 2011	Jul. 31, 2011 segments
Number of reportable operating segments	3		3		3
Net sales	$ 99,141,000	$ 162,811,000	$ 212,502,000	$ 340,971,000
Operating Income (loss)	10,654,000	25,264,000	26,413,000	65,345,000
Interest income and other (expense)	434,000	626,000	930,000	1,320,000
Interest expense	2,183,000	2,090,000	4,329,000	4,153,000
Depreciation and amortization	5,089,000	7,037,000	10,101,000	13,370,000
Expenditure for long-lived assets, including intangibles	1,217,000	1,400,000	2,660,000	8,853,000
Total assets	765,400,000	998,563,000	765,400,000	998,563,000	937,509,000
Costs related to a contested proxy solicitation			2,638,000
Merger termination fee, net	0	0	0	12,500,000
Amortization of stock-based compensation	1,036,000	1,351,000	1,909,000	2,859,000
Telecommunications Transmission Segment [Member]
Net sales	51,328,000	62,268,000	108,124,000	111,409,000
Operating Income (loss)	8,319,000	15,450,000	21,353,000	23,770,000
Interest income and other (expense)	14,000	16,000	20,000	87,000
Interest expense	166,000	159,000	332,000	240,000
Depreciation and amortization	2,507,000	2,887,000	5,074,000	5,652,000
Expenditure for long-lived assets, including intangibles	799,000	899,000	2,070,000	7,872,000
Total assets	241,369,000	256,111,000	241,369,000	256,111,000
R F Microwave Amplifiers Segment [Member]
Net sales	22,437,000	23,889,000	43,550,000	46,689,000
Operating Income (loss)	1,195,000	407,000	1,518,000	1,044,000
Interest income and other (expense)	(3,000)	(5,000)	(6,000)	(2,000)
Interest expense	0	0	0	0
Depreciation and amortization	1,101,000	1,122,000	2,204,000	2,243,000
Expenditure for long-lived assets, including intangibles	369,000	227,000	475,000	306,000
Total assets	103,445,000	101,400,000	103,445,000	101,400,000
Mobile Data Communications Segment [Member]
Net sales	25,376,000	76,654,000	60,828,000	182,873,000
Operating Income (loss)	4,408,000	14,320,000	13,771,000	39,383,000
Interest income and other (expense)	7,000	12,000	16,000	24,000
Interest expense	0	0	0	0
Depreciation and amortization	397,000	1,611,000	817,000	2,483,000
Expenditure for long-lived assets, including intangibles	49,000	271,000	115,000	628,000
Total assets	25,160,000	48,283,000	25,160,000	48,283,000
Unallocated [Member]
Net sales	0	0	0	0
Operating Income (loss)	(3,268,000)	(4,913,000)	(10,229,000)	1,148,000
Interest income and other (expense)	416,000	603,000	900,000	1,211,000
Interest expense	2,017,000	1,931,000	3,997,000	3,913,000
Depreciation and amortization	1,084,000	1,417,000	2,006,000	2,992,000
Expenditure for long-lived assets, including intangibles	0	3,000	0	47,000
Total assets	395,426,000	592,769,000	395,426,000	592,769,000
Telecommunications Transmission Sales to RF Microwave Amplifiers [Member]
Intersegment sales	985,000	1,154,000	1,699,000	1,862,000
Telecommunications Transmissions Sales to Mobile Data Communications [Member]
Intersegment sales	1,400,000	7,658,000	4,890,000	14,309,000
RF Microwave Amplifiers Sales to Telecommunications Transmission [Member]
Intersegment sales	$ 83,000	$ 0	$ 85,000	$ 31,000