Goodwill (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
Goodwill [Line Items]
Number of reportable operating segments	3us-gaap_NumberOfOperatingSegments	3us-gaap_NumberOfOperatingSegments	3us-gaap_NumberOfOperatingSegments	3us-gaap_NumberOfOperatingSegments	3us-gaap_NumberOfOperatingSegments
Goodwill, Impaired, Accumulated Impairment Loss [Abstract]
Goodwill gross	$ 150,603,000us-gaap_GoodwillGross		$ 150,603,000us-gaap_GoodwillGross		$ 150,603,000us-gaap_GoodwillGross
Goodwill accumulated impairment	(13,249,000)		(13,249,000)		(13,249,000)
Goodwill	137,354,000us-gaap_Goodwill		137,354,000us-gaap_Goodwill		137,354,000us-gaap_Goodwill
Telecommunications Transmission Segment
Goodwill, Impaired, Accumulated Impairment Loss [Abstract]
Goodwill gross	107,779,000		107,779,000		107,779,000
Goodwill accumulated impairment	0		0		0
Goodwill	107,779,000		107,779,000		107,779,000
RF Microwave Amplifiers Segment
Goodwill, Impaired, Accumulated Impairment Loss [Abstract]
Goodwill gross	29,575,000		29,575,000		29,575,000
Goodwill accumulated impairment	0		0		0
Goodwill	29,575,000		29,575,000		29,575,000
Mobile Data Communications Segment
Goodwill, Impaired, Accumulated Impairment Loss [Abstract]
Goodwill gross	13,249,000		13,249,000		13,249,000
Goodwill accumulated impairment	(13,249,000)		(13,249,000)		(13,249,000)
Goodwill	$ 0		$ 0		$ 0

Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 20

-Section 50

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=35741047&loc=d3e13816-109267

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 20

-Section 45

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6388280&loc=d3e13770-109266

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Amount before accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (a,h)

-URI http://asc.fasb.org/extlink&oid=35741047&loc=d3e13816-109267

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Number of operating segments. An operating segment is a component of an enterprise: (a) that engages in business activities from which it may earn revenues and incur expenses (including revenues and expenses relating to transactions with other components of the same enterprise), (b) whose operating results are regularly reviewed by the enterprise's chief operating decision maker to make decisions about resources to be allocated to the segment and assess its performance, and (c) for which discrete financial information is available. An operating segment may engage in business activities for which it has yet to earn revenues, for example, start-up operations may be operating segments before earning revenues.

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