Signals Defense LLC, a Maryland based certified small business enterprise, is the sole source of patented SD Technology. Signals Defense, LLC is the sole source of patented SD Technology. Contact us directly for product and installation quote. SD Technology is available for government purchase on GSA Schedule 84. Contact us for other options to meet your procurement goals. Signals Defense products can be purchased with green energy program funds. A small list of our products can be purchased online from our Signals Defense store.