Note 3 - Concentration of Credit Risk (Details Textual) - USD ($)	3 Months Ended	12 Months Ended
Mar. 31, 2023	Mar. 31, 2022	Dec. 31, 2022
Cash and Cash Equivalents, at Carrying Value	$ 11,001,000		$ 14,365,000
Cash Equivalents, at Carrying Value	9,200,000		11,700,000
Cash, Uninsured Amount	900,000		1,500,000
Accounts Receivable, Allowance for Credit Loss, Current	$ 36,000		$ 36,000
Customer Concentration Risk [Member] \| Accounts Receivable [Member] \| Two Customers [Member]
Concentration Risk, Percentage	33.80%		66.00%
Customer Concentration Risk [Member] \| Revenue Benchmark [Member] \| Customer A [Member]
Concentration Risk, Percentage	28.30%	14.30%
Customer Concentration Risk [Member] \| Revenue Benchmark [Member] \| Customer B [Member]
Concentration Risk, Percentage	15.90%	13.30%
Customer Concentration Risk [Member] \| Revenue Benchmark [Member] \| Customer C [Member]
Concentration Risk, Percentage	10.60%	11.60%
DENMARK
Cash, Uninsured Amount	$ 600,000		$ 500,000

Amount of allowance for credit loss on accounts receivable, classified as current.

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Amount of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. Excludes cash and cash equivalents within disposal group and discontinued operation.

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Amount of short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. Excludes cash and cash equivalents within disposal group and discontinued operation.

+ References

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The amount of cash as of the balance sheet date that is not insured by the Federal Deposit Insurance Corporation.

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For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

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