Note 16 - New Accounting Pronouncements (Details) - Schedule of Changes in Accounting Principals - USD ($)	3 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Sales Distribution
Sales by revenue category	$ 1,814,214	$ 3,542,077
Commercial [Member]
Sales Distribution
Sales by revenue category	721,632
Government Sales [Member]
Sales Distribution
Sales by revenue category	1,092,582
Test Units [Member] | Commercial [Member]
Sales Distribution
Sales by revenue category	334,232
Test Units [Member] | Government Sales [Member]
Sales Distribution
Sales by revenue category	1,092,582
Repairs and Calibration [Member] | Commercial [Member]
Sales Distribution
Sales by revenue category	332,699
Repairs and Calibration [Member] | Government Sales [Member]
Sales Distribution
Sales by revenue category	0
Replacement Parts [Member] | Commercial [Member]
Sales Distribution
Sales by revenue category	45,768
Replacement Parts [Member] | Government Sales [Member]
Sales Distribution
Sales by revenue category	0
Extended Warranty [Member] | Commercial [Member]
Sales Distribution
Sales by revenue category	8,933
Extended Warranty [Member] | Government Sales [Member]
Sales Distribution
Sales by revenue category	$ 0