TECHNIQUE FOR IMPLEMENTING A DELAY IN THE T1 TRANSMISSION PATH OF SIMULCAST SYSTEM
Original Publication Date: 1992-May-01
Included in the Prior Art Database: 2002-Jan-07
In a simulcast system the remote sites are linked to the prime site through digital loop consisting of Tl chan- nel banks and microwave links each having its own path delays. If one of the liiks break the atTected remote site could be reached through alternate path. However the path condition to the affected area will be different and hence it is necessary to optimize the system through Prime Optimization Node (PON) to compensate the amplitude and phase of signals received at the overlap area. The present system has the capability to compen- sate the time delay up to 5.333 milliseconds. But in a large simulcast system with multiple liis this time delay will not be sufficient to compensate for the phase delay. The purpose of Tl delay unit' is to introduce time delay in the Tl path from 1 microsecond to 20 milliseconds in steps of one microsecond. This paper describes the tech- nique in implementing the delay in Tl lime. The delay unit consists of a transformer interface to Tl lime, a Tl repeater to recover data and clock from AMI (Alternate Mark Inversion) line code and the time delay circuit. The receive transformer converts the bipolar AM1 sig- nal to unipolar and the transmit transformer reconstructs the delayed unipolar TTL signal to bipolar AM1 signal for onward transmission.