Concentration of Customers (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Oct. 31, 2013	Oct. 31, 2012
Revenues	$ 127	$ 468
Straight Path Spectrum [Member]
Revenues	107	141
Covad Communications Group [Member] | Straight Path Spectrum [Member]
Revenues	41
AT&T[Member] | Straight Path Spectrum [Member]
Revenues	31
Airband Communications [Member] | Straight Path Spectrum [Member]
Revenues	$ 15