CONTROL NETWORK TO PREVENT RAILING OF PLL WITH LOSS OF REFERENCE FREQUENCY
Original Publication Date: 1996-Aug-01
Included in the Prior Art Database: 2002-Apr-18
In the iDEN base station, a voltage controlled crystal oscillator is phase locked to a high stability external frequency reference. In the event of the loss ofthis reference frequency to the station, the crystal oscillator's control voltage will go to a railed state. This results in the radio transmitting on a wrong frequency (channel) and the inability to receive a signal, forcing the radio to be immediately shut down, causing a loss of calls. This is especially a problem when the external reference is momentarily broken to add another station to the system.