Note 8 - Segment Reporting (Details) - Total revenues by products and services (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Jul. 31, 2013	Jul. 31, 2012
Products and services:
Total sales	$ 6,774	$ 4,257
Electronic Manufacturing [Member]
Products and services:
Total sales	4,247	2,483
Remote Monitoring Solutions [Member]
Products and services:
Total sales	1,526	954
Industrial Data Communications [Member]
Products and services:
Total sales	243	216
Mobile Data Acquisition [Member]
Products and services:
Total sales	662	434
EMS Related Services [Member]
Products and services:
Total sales	61	71
Proprietary Product Related Services [Member]
Products and services:
Total sales	$ 35	$ 99