Note 4 - Revenue Disaggregation - Costs, Estimated Earnings, and Billings on Uncompleted Contracts (Details)	Jun. 30, 2021 USD ($)
Costs incurred on contracts in progress	$ 4,882,600
Estimated earnings	2,900,056
Costs and Estimated Earnings on Uncompleted Contracts	7,782,656
Billings to date	(7,098,362)
Net Cost in Excess of Billings	684,294
Deferred revenue related to non-systems contracts	(618,984)
Contract Liability In Excess of Contract Assets	65,310
Included in accompanying balance sheets
Contract assets	1,066,382
Contract liabilities	$ (1,001,072)