Condensed Consolidated Statements of Cash Flows - USD ($)	9 Months Ended
	Apr. 30, 2020	Apr. 30, 2019
Cash flows from operating activities:
Net income	$ 5,894,000	$ 18,906,000
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization of property, plant and equipment	8,022,000	8,618,000
Amortization of intangible assets with finite lives	15,952,000	13,113,000
Amortization of stock-based compensation	3,098,000	3,356,000
Amortization of deferred financing costs	553,000	916,000
Estimated contract settlement costs	444,000	6,351,000
Write-off of deferred financing costs	0	3,217,000
Settlement of intellectual property litigation	0	(3,204,000)
Change in other liabilities	(3,100,000)	(23,000)
Loss on disposal of property, plant and equipment	3,000	40,000
(Benefit from) provision for allowance for doubtful accounts	(364,000)	854,000
Provision for excess and obsolete inventory	1,238,000	2,450,000
Deferred income tax expense	1,374,000	3,885,000
Changes in assets and liabilities, net of effects of business acquisitions:
Accounts receivable	10,129,000	10,970,000
Inventories	(5,689,000)	(9,136,000)
Prepaid expenses and other current assets	(4,080,000)	(1,569,000)
Other assets	(20,000)	(34,000)
Accounts payable	6,748,000	(8,611,000)
Accrued expenses and other current liabilities	(78,000)	5,722,000
Contract liabilities	1,063,000	1,333,000
Other liabilities, non-current	303,000	377,000
Interest payable	(307,000)	69,000
Income taxes payable	(2,176,000)	(3,757,000)
Net cash provided by operating activities	39,007,000	53,843,000
Cash flows from investing activities:
Payment for acquisition of CGC, net of cash acquired	(11,165,000)	0
Payment for acquisition of Solacom, net of cash acquired	0	(25,883,000)
Payment for acquisition of NG-911 Inc. and the GD NG-911 business	(781,000)	(10,000,000)
Purchases of property, plant and equipment	(4,420,000)	(6,388,000)
Net cash used in investing activities	(16,366,000)	(42,271,000)
Cash flows from financing activities:
Net (payments) borrowings of long-term debt under Credit Facility	(5,600,000)	173,500,000
Net payments under Revolving Loan portion of Prior Credit Facility	0	(48,603,000)
Repayment of debt under Term Loan portion of Prior Credit Facility	0	(120,121,000)
Remittance of employees' statutory tax withholdings for stock awards	(5,274,000)	(5,032,000)
Cash dividends paid	(7,553,000)	(7,381,000)
Payment of deferred financing costs	0	(1,813,000)
Repayment of principal amounts under finance lease and other obligations	(314,000)	(1,189,000)
Proceeds from issuance of employee stock purchase plan shares	690,000	709,000
Payment of shelf registration costs	0	(148,000)
Proceeds from exercises of stock options	468,000	174,000
Net cash used in financing activities	(17,583,000)	(9,904,000)
Net increase in cash and cash equivalents	5,058,000	1,668,000
Cash and cash equivalents at beginning of period	45,576,000	43,484,000
Cash and cash equivalents at end of period	50,634,000	45,152,000
Cash paid during the period for:
Interest	4,546,000	5,853,000
Income taxes, net	2,330,000	1,582,000
Non-cash investing and financing activities:
Reclass of finance lease right-of-use assets to property, plant and equipment	698,000	0
Cash dividends declared but unpaid (including dividend equivalents)	2,635,000	2,653,000
Accrued additions to property, plant and equipment	1,201,000	1,248,000
Common stock issued for acquisitions	11,575,000	5,606,000
Accruals related to acquisitions	$ 4,020,000	$ 0