Business Segments - Product Category (Details) - USD ($)	3 Months Ended
Jun. 28, 2020	Jun. 30, 2019
Revenue and Gross Profit from External Customers
Revenues	$ 119,813,500	$ 130,729,300
Gross Profit	18,825,700	25,263,500
Base station infrastructure
Revenue and Gross Profit from External Customers
Revenues	68,855,000	69,069,000
Gross Profit	11,418,000	14,521,000
Network systems
Revenue and Gross Profit from External Customers
Revenues	19,400,000	22,552,000
Gross Profit	2,133,000	3,927,000
Installation, test and maintenance
Revenue and Gross Profit from External Customers
Revenues	5,462,000	6,025,000
Gross Profit	766,000	1,084,000
Mobile device accessories
Revenue and Gross Profit from External Customers
Revenues	26,097,000	33,083,000
Gross Profit	$ 4,509,000	$ 5,732,000

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Aggregate revenue less cost of goods and services sold or operating expenses directly attributable to the revenue generation activity.

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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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