Business Segments - Product Category (Details) - USD ($)	3 Months Ended		6 Months Ended
	Sep. 25, 2016	Sep. 27, 2015	Sep. 25, 2016	Sep. 27, 2015
Revenue and Gross Profit from External Customers
Revenues	$ 134,633,800	$ 142,353,300	$ 263,493,800	$ 277,017,300
Gross Profit	28,755,600	30,511,700	55,861,600	59,493,600
Base station infrastructure
Revenue and Gross Profit from External Customers
Revenues	52,502,000	56,275,000	104,897,000	110,098,000
Gross Profit	13,453,000	13,662,000	26,881,000	27,758,000
Network systems
Revenue and Gross Profit from External Customers
Revenues	21,461,000	22,425,000	39,891,000	43,619,000
Gross Profit	3,421,000	3,372,000	6,319,000	6,483,000
Installation, test and maintenance
Revenue and Gross Profit from External Customers
Revenues	6,881,000	9,012,000	15,636,000	17,630,000
Gross Profit	1,376,000	1,867,000	2,944,000	3,497,000
Mobile device accessories
Revenue and Gross Profit from External Customers
Revenues	53,790,000	54,641,000	103,070,000	105,670,000
Gross Profit	$ 10,506,000	$ 11,611,000	$ 19,718,000	$ 21,756,000