Tom's Tech Talk (#11): Antenna Systems

 I can’t tell you how many times we run across systems improperly designed based on their licensing requirements. Each FCC licensee is required to meet both height and power requirements for all of their fixed base station equipment that is indicated on their license.

      Many times people take the approach that to reach their people in the field they need to increase the gain of their antenna’s and the power on their base stations. What they don’t realize is that they may become an interferer with an adjacent co-channel user and  are therefore  subjected to a fine by the FCC for exceeding their licensed effective radiated power. We had one instance where the combined antenna gain and power from their equipment was enough to reach Madison Wisconsin from the Western Suburbs of Chicago.

Tom's Tech Talk (#10): Digital Mobile Radio System Implementation

      In today’s Digital Mobile Radio systems, networking is playing a key role in implementation of these radio systems. Years past connectivity was through an in house set of wires or over the local telephone companies telephone line. With the evolution of radio, not only has product changed, but the way we need to get the information between sites has changed.

      In the early years, radio equipment was controlled by Direct Current (DC) traveling down the telephone lines between dispatch and the radio at a tower. The voice and DC current would travel the line to the equipment. The equipment in turn would interpret the DC current as one of the following:

 1)      Transmit on F1

 2)      Transmit on F2

 3)      Monitor the Channel