Note 16 - New Accounting Pronouncements (Details) - Schedule of Changes in Accounting Principals - USD ($)	3 Months Ended	9 Months Ended
	Dec. 31, 2018	Dec. 31, 2018
Commercial [Member]
Sales Distribution
Sales by revenue category	$ 491,356	$ 2,151,830
Government Sales [Member]
Sales Distribution
Sales by revenue category	3,484,380	5,861,061
Test Units [Member] | Commercial [Member]
Sales Distribution
Sales by revenue category	46,631	642,855
Test Units [Member] | Government Sales [Member]
Sales Distribution
Sales by revenue category	3,484,380	5,861,061
Repairs and Calibration [Member] | Commercial [Member]
Sales Distribution
Sales by revenue category	366,563	1,285,839
Repairs and Calibration [Member] | Government Sales [Member]
Sales Distribution
Sales by revenue category	0	0
Replacement Parts [Member] | Commercial [Member]
Sales Distribution
Sales by revenue category	64,527	189,881
Replacement Parts [Member] | Government Sales [Member]
Sales Distribution
Sales by revenue category	0	0
Extended Warranty [Member] | Commercial [Member]
Sales Distribution
Sales by revenue category	13,635	33,255
Extended Warranty [Member] | Government Sales [Member]
Sales Distribution
Sales by revenue category	$ 0	$ 0