Note 2 - Basis of Presentation and Significant Accounting Policies (Details Textual) $ in Thousands	12 Months Ended
	Sep. 30, 2021 USD ($)	Sep. 30, 2020 USD ($)	Dec. 31, 2020 USD ($)	Sep. 30, 2019 USD ($)
Number of Additional Inactive Subsidiaries	2
Investments, Typical Final Maturity Maximum (Year)	3 years
Investments, Typical Portfolio Weighted Average Maturity (Month)	18 months
Cash and Cash Equivalents, at Carrying Value, Ending Balance	$ 13,167	$ 23,319
Restricted Cash and Cash Equivalents, Total	1,361	677
Deferred Revenue for Collection Issues	0	0
Accounts Receivable, Allowance for Credit Loss, Ending Balance	127	130
Inventory Obsolescence Write Down (Recoveries)	(183)	(37)
Cost of Revenue, Total	23,577	20,371
Revenue from Contract with Customer, Including Assessed Tax	47,003	43,010
Advertising Expense	193	263
Standard and Extended Product Warranty Accrual, Ending Balance	146	126		$ 150
Impairment of Intangible Assets, Finite-lived	$ 0	$ 0
Number of Reportable Segments	2	2
Number of Operating Segments		2
Foreign Currency Transaction Gain (Loss), before Tax, Total	$ 260
Immaterial Correction of Prior Period Financial Statements [Member]
Prepaid Expenses and Accrued Liabilities			$ 5,205
Shipping and Handling [Member]
Cost of Revenue, Total	232	$ 259
Revenue from Contract with Customer, Including Assessed Tax	$ 266	$ 241
Minimum [Member]
Property, Plant and Equipment, Useful Life (Year)	2 years
Finite-Lived Intangible Asset, Useful Life (Year)	3 years
Maximum [Member]
Property, Plant and Equipment, Useful Life (Year)	7 years
Finite-Lived Intangible Asset, Useful Life (Year)	15 years
Customer Concentration Risk [Member] | Accounts Receivable [Member]
Number Of Major Customers	2	2
Customer Concentration Risk [Member] | Accounts Receivable [Member] | Customer 1 [Member]
Concentration Risk, Percentage	66.00%	36.00%
Customer Concentration Risk [Member] | Accounts Receivable [Member] | Customer 2 [Member]
Concentration Risk, Percentage	18.00%	24.00%