Abstract: A portable digital communications system is provided that signals the communications recipient of a worsening wireless link with communication partners. In audio communication systems, static is introduced as the alert signal, along with the decoded data that was transmitted. Static gives the communications recipient a qualitative feeling of the wireless link status. In response to the static signal, communications recipients move their positions to improve the link. In a video communications system, static and/or “snow” are introduced as the alert signal to give the recipient a qualitative feeling of the wireless link status. The invention allows the warning signal to be mixed with the decoded data, mixed with simulated data generated to replace incorrectly decoded data, or presented without data. In addition, static is introduced in response to averaging schemes to more closely simulate the performance of static and/or “snow” in an analog receivers.

Abstract: A method is provided for a mobile station to calculate the time intervals at which it monitors cells in a cellular phone system to find the mobile station's home network in the phone system. The monitoring varies with the rate at which the mobile station reselects proximate cells to locate itself in a telephone network. The time between cell selections is used as an indication of the mobile station's mobility. The variable search intervals, determined by the time intervals at which the mobile station reselects cells, is limited to insure that the mobile station at least monitors for its home network at a minimum specified interval of time. An apparatus is also provided to initiate home network monitoring at time intervals related to rate at which cells in a cellular phone system are reselected by a mobile station.