Studio to transmitter links are always a topic for discussion at engineering conferences and the NAB Show was no exception with a session on STL on IP and the use of Part 101 frequencies, “Extending IP Audio to the Transmitter Using Part 101 or Unlicensed IP Radios.”
Those frequencies are commercial frequencies (6, 11, 18 and 23 GHz) that can be licensed for 10 years to allow bidirectional IP transmission and reception. Jeff Holdenrid of Double Radius said Part 101 frequencies allow for stable latency, and if designed properly, the user has mission critical reliability.
He explained some risks if unlicensed data links are used for a STL. “There are 7,000 wireless service providers in the country today, and their focus is to provide internet access to the people that can’t get it (wired).” Those providers in rural areas use 2.4, 3.65 and 5.8 GHz and the 900 MHz band to provide internet to homes. Holdenrid said when another user on the unlicensed frequencies starts transmitting, it can affect STLs sharing those frequencies.
He said that engineers who are considering the use of a 5.8 GHz STL link should be using a spectrum analyzer to determine the noise floor. “If they are going Part 101, they are taking a step forward by owning the frequency, and they don’t have to worry about interference.”
