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Note B - Summary of Significant Accounting Policies (Details Textual)
$ in Thousands
12 Months Ended
Dec. 31, 2021
USD ($)
Dec. 31, 2020
USD ($)
Dec. 31, 2019
USD ($)
Cash and Cash Equivalents, at Carrying Value, Ending Balance $ 34,656 $ 43,425  
Cash, Uninsured Amount $ 23,100    
Number of Patents Issued 328    
Asset Impairment Charges, Total $ 0 0 $ 0
Product Warranty Accrual, Current 263 703  
Advertising Expense $ 100 $ 400 $ 500
Minimum [Member]      
Product Warranty Extension Period (Year) 3 years    
Maximum [Member]      
Product Warranty Extension Period (Year) 5 years    
Patents [Member] | Minimum [Member]      
Finite-Lived Intangible Asset, Useful Life (Year) 10 years    
Patents [Member] | Maximum [Member]      
Finite-Lived Intangible Asset, Useful Life (Year) 20 years    
Customer Concentration Risk [Member] | Revenue Benchmark [Member]      
Number of Customers 5 5 5
Customer Concentration Risk [Member] | Revenue Benchmark [Member] | Five Customers [Member]      
Concentration Risk, Percentage 67.00% 73.30% 80.70%
Customer Concentration Risk [Member] | Revenue Benchmark [Member] | ATX Networks Corporation [Member]      
Concentration Risk, Percentage 25.60%    
Customer Concentration Risk [Member] | Revenue Benchmark [Member] | Microsoft [Member]      
Concentration Risk, Percentage 14.10% 38.30%  
Customer Concentration Risk [Member] | Revenue Benchmark [Member] | Cisco [Member]      
Concentration Risk, Percentage 11.90%    
Customer Concentration Risk [Member] | Revenue Benchmark [Member] | Amazon [Member]      
Concentration Risk, Percentage   11.50%  
Customer Concentration Risk [Member] | Accounts Receivable [Member]      
Number of Customers 5 5  
Customer Concentration Risk [Member] | Accounts Receivable [Member] | Five Customers [Member]      
Concentration Risk, Percentage 70.60% 64.60%  
Customer Concentration Risk [Member] | Accounts Receivable [Member] | ATX Networks Corporation [Member]      
Concentration Risk, Percentage 41.70%    
Customer Concentration Risk [Member] | Accounts Receivable [Member] | Microsoft [Member]      
Concentration Risk, Percentage   8.50%  
Customer Concentration Risk [Member] | Accounts Receivable [Member] | Cisco [Member]      
Concentration Risk, Percentage 3.50%    
Non-US [Member]      
Cash and Cash Equivalents, at Carrying Value, Ending Balance $ 17,300 $ 10,700