Segment Information (Details) (USD $)	3 Months Ended		6 Months Ended		12 Months Ended
	Jan. 31, 2015 operating_segment	Jan. 31, 2014 operating_segment	Jan. 31, 2015 operating_segment	Jan. 31, 2014 operating_segment	Jul. 31, 2014 operating_segment
Segment Reporting Information [Line Items]
Number of reportable operating segments	3	3	3	3	3
Net sales	$ 81,802,000	$ 85,499,000	$ 158,193,000	$ 168,867,000
Operating income (loss)	10,623,000	11,172,000	18,842,000	21,271,000
Interest income and other (expense)	90,000	228,000	174,000	501,000
Interest expense (income)	69,000	1,998,000	334,000	4,016,000
Depreciation and amortization	4,243,000	4,324,000	8,749,000	8,563,000
Expenditure for long-lived assets, including intangibles	1,398,000	2,397,000	2,145,000	3,424,000
Total assets	471,487,000	655,214,000	471,487,000	655,214,000	473,852,000
Amortization of stock-based compensation	1,061,000	1,069,000	2,398,000	2,016,000
Telecommunications Transmission Segment [Member]
Segment Reporting Information [Line Items]
Net sales	53,867,000	56,521,000	105,223,000	110,886,000
Operating income (loss)	11,049,000	10,268,000	19,215,000	19,197,000
Interest income and other (expense)	(26,000)	(18,000)	(55,000)	(12,000)
Interest expense (income)	69,000	61,000	136,000	120,000
Depreciation and amortization	2,196,000	2,231,000	4,409,000	4,490,000
Expenditure for long-lived assets, including intangibles	742,000	1,981,000	1,280,000	2,914,000
Total assets	240,413,000	244,478,000	240,413,000	244,478,000
RF Microwave Amplifiers Segment [Member]
Segment Reporting Information [Line Items]
Net sales	21,646,000	22,041,000	40,410,000	42,238,000
Operating income (loss)	969,000	1,077,000	2,032,000	1,668,000
Interest income and other (expense)	(7,000)	(13,000)	(25,000)	(18,000)
Interest expense (income)	0	0	0	0
Depreciation and amortization	906,000	945,000	1,785,000	1,888,000
Expenditure for long-lived assets, including intangibles	582,000	163,000	674,000	257,000
Total assets	92,918,000	90,733,000	92,918,000	90,733,000
Mobile Data Communications Segment
Segment Reporting Information [Line Items]
Net sales	6,289,000	6,937,000	12,560,000	15,743,000
Operating income (loss)	2,709,000	3,273,000	5,576,000	7,379,000
Interest income and other (expense)	3,000	3,000	6,000	6,000
Interest expense (income)	0	(3,000)	0	(3,000)
Depreciation and amortization	72,000	63,000	142,000	137,000
Expenditure for long-lived assets, including intangibles	60,000	246,000	144,000	246,000
Total assets	6,002,000	7,114,000	6,002,000	7,114,000
Unallocated [Member]
Segment Reporting Information [Line Items]
Net sales	0	0	0	0
Operating income (loss)	(4,104,000)	(3,446,000)	(7,981,000)	(6,973,000)
Interest income and other (expense)	120,000	256,000	248,000	525,000
Interest expense (income)	0	1,940,000	198,000	3,899,000
Depreciation and amortization	1,069,000	1,085,000	2,413,000	2,048,000
Expenditure for long-lived assets, including intangibles	14,000	7,000	47,000	7,000
Total assets	132,154,000	312,889,000	132,154,000	312,889,000
Amortization of stock-based compensation	1,061,000	1,069,000	2,398,000	2,016,000
Expenses related to strategic alternatives analysis	0	0	585,000	0
Telecommunications Transmission Sales to RF Microwave Amplifiers [Member]
Segment Reporting Information [Line Items]
Intersegment sales	720,000	464,000	1,009,000	765,000
Telecommunications Transmissions Sales to Mobile Data Communications [Member]
Segment Reporting Information [Line Items]
Intersegment sales	141,000	134,000	337,000	172,000
Rf Microwave Amplifiers Sales To Telecommunications Transmission [Member]
Segment Reporting Information [Line Items]
Intersegment sales	$ 0	$ 68,000	$ 0	$ 134,000