Technical considerations in the design of a 2 GHz DS-3 digital Radio for overbuilding on existing analog routes

With the advancement of digital technology, it is becoming economically and technically more advantageous to replace conventional analog radio systems with digital radio systems. One of the key questions frequently being studied is the co-existing of new digital radio systems in the same frequency band and along common routes, with analog radio systems currently in service. Technical considerations in the design of a 2 GHz DS-3 digital radio at 44.736 Mb/s or 34.368 Mb/s for overbuilding on existing analog routes are described. These technical considerations include the choice of modulation technique, filtering strategy, and the digital co-existence interference objectives with either analog message or analog video FM systems. For frequency coordination in actual systems, results presented can be used to establish the co-existence principles in order to minimize the degradation incurred through mutual interference between the analog and digital systems.