Note 8 - Segment Reporting (Tables)
9 Months Ended
Jan. 31, 2014
Segment Reporting [Abstract]  
Schedule of Segment Reporting Information, by Segment [Table Text Block]
   
Three Months Ended January 31, 2014
 
   
OEM
   
Proprietary
   
Total
 
                   
Total revenues
  $ 3,032     $ 4,651     $ 7,683  
                         
Gross margin
  $ 698     $ 2,224     $ 2,922  
   
Three Months Ended January 31, 2013
 
   
OEM
   
Proprietary
   
Total
 
                         
Total revenues
  $ 4,424     $ 3,034     $ 7,458  
                         
Gross margin
  $ 1,226     $ 1,577     $ 2,803  
   
Nine Months Ended January 31, 2014
 
   
OEM
   
Proprietary
   
Total
 
                         
Total revenues
  $ 10,930     $ 10,857     $ 21,787  
                         
Gross margin
  $ 2,772     $ 5,386     $ 8,158  
                         
Goodwill
  $ -     $ 1,942     $ 1,942  
   
Nine Months Ended January 31, 2013
 
   
OEM
   
Proprietary
   
Total
 
                         
Total revenues
  $ 9,968     $ 7,885     $ 17,853  
                         
Gross margin
  $ 2,574     $ 4,029     $ 6,603  
                         
Goodwill
  $ -     $ 1,942     $ 1,942  
Revenue from External Customers by Products and Services [Table Text Block]
   
Three Months Ended
January 31,
   
Nine Months Ended
January 31,
 
   
2014
   
2013
   
2014
   
2013
 
Products and services:
                       
  OEM solutions
  $ 2,984     $ 4,382     $ 10,757     $ 9,800  
  Remote monitoring solutions
    3,926       1,357       8,260       4,208  
  Industrial data communications
    333       113       829       624  
  Mobile data acquisition
    265       1,484       1,439       2,765  
  Other services:
                               
    OEM related services
    48       42       173       168  
    Proprietary product related services
    127       80       329       287  
Total sales
  $ 7,683     $ 7,458     $ 21,787     $ 17,853