Consolidated Statements of Cash Flows - USD ($)	12 Months Ended
	Jul. 31, 2020	Jul. 31, 2019	Jul. 31, 2018
Cash flows from operating activities:
Net income	$ 7,020,000	$ 25,041,000	$ 29,769,000
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization of property, plant and equipment	10,561,000	11,927,000	13,655,000
Amortization of intangible assets with finite lives	21,595,000	18,320,000	21,075,000
Amortization of stock-based compensation	9,275,000	11,427,000	8,569,000
Amortization of deferred financing costs	737,000	1,099,000	2,196,000
Estimated contract settlement costs	444,000	6,351,000	0
Settlement of intellectual property litigation	0	(3,204,000)	0
Write-off of deferred financing costs	0	3,217,000	0
Changes in other liabilities	(4,133,000)	(1,056,000)	0
Loss on disposal of property, plant and equipment	0	144,000	79,000
(Benefit from) provision for allowance for doubtful accounts	(431,000)	1,136,000	573,000
Provision for excess and obsolete inventory	1,647,000	6,015,000	5,628,000
Deferred income tax expense (benefit)	860,000	4,283,000	(6,379,000)
Changes in assets and liabilities, net of effects of business acquisitions:
Accounts receivable	20,929,000	6,315,000	(24,578,000)
Inventories	(9,132,000)	(3,787,000)	(20,065,000)
Prepaid expenses and other current assets	(2,261,000)	915,000	787,000
Other assets	(719,000)	102,000	(140,000)
Accounts payable	(2,206,000)	(21,290,000)	13,728,000
Accrued expenses and other current liabilities	4,292,000	3,554,000	(3,374,000)
Contract liabilities	(6,312,000)	(127,000)	9,143,000
Other liabilities, non-current	2,422,000	(84,000)	(682,000)
Interest payable	(397,000)	151,000	234,000
Income taxes payable	(1,427,000)	(2,418,000)	126,000
Net cash provided by operating activities	52,764,000	68,031,000	50,344,000
Cash flows from investing activities:
Purchases of property, plant and equipment	(7,225,000)	(8,785,000)	(8,642,000)
Net cash used in investing activities	(20,184,000)	(44,668,000)	(8,642,000)
Cash flows from financing activities:
Net (payments) borrowings of long-term debt under Credit Facility	(15,500,000)	165,000,000	0
Net payments under Revolving Loan portion of Prior Credit Facility	0	(48,603,000)	(8,800,000)
Repayment of debt under Term Loan portion of Prior Credit Facility	0	(120,121,000)	(18,960,000)
Remittance of employees' statutory tax withholdings for stock awards	(5,276,000)	(5,042,000)	(1,143,000)
Cash dividends paid	(10,020,000)	(9,789,000)	(9,538,000)
Repayment of principal amounts under finance lease and other obligations	(805,000)	(1,906,000)	(2,802,000)
Payment of deferred financing costs	0	(1,813,000)	0
Proceeds from issuance of employee stock purchase plan shares	855,000	935,000	855,000
Proceeds from exercises of stock options	468,000	216,000	326,000
Payment of shelf registration costs	0	(148,000)	0
Net cash used in financing activities	(30,278,000)	(21,271,000)	(40,062,000)
Net increase in cash and cash equivalents	2,302,000	2,092,000	1,640,000
Cash and cash equivalents at beginning of year	45,576,000	43,484,000	41,844,000
Cash and cash equivalents at end of year	47,878,000	45,576,000	43,484,000
Supplemental cash flow disclosure
Interest paid during the year	5,549,000	7,669,000	7,291,000
Income taxes paid during the year	2,875,000	2,005,000	1,112,000
Non-cash investing and financing activities:
Reclass of finance lease right-of-use assets to property, plant and equipment	698,000	0	0
Accrued remittance of employees' statutory tax withholdings for fully-vested share units	1,399,000	1,787,000	2,963,000
Cash dividends declared but unpaid (including accrual of dividend equivalents)	2,762,000	2,733,000	2,656,000
Finance lease and other obligations incurred	0	0	1,306,000
Accrued additions to property, plant and equipment	1,408,000	902,000	719,000
Issuance (forfeiture) of restricted stock	0	1,000	(1,000)
Common stock issued for acquisitions	11,575,000	5,606,000	0
Accruals related to acquisitions	1,157,000	0	0
CGC
Cash flows from investing activities:
Payment for acquisitions, net of cash acquired	(11,165,000)	0	0
Solacom
Cash flows from investing activities:
Payment for acquisitions, net of cash acquired	0	(25,883,000)	0
GD NG-911 business
Cash flows from investing activities:
Payment for acquisition of businesses	(1,013,000)	(10,000,000)	0
NG-911
Cash flows from investing activities:
Payment for acquisition of businesses	$ (781,000)	$ 0	$ 0