Abstract: A selective call base station (100) for receiving a signal comprising a plurality of communication signals has an Analog-to-Digital (A/D) converter (220) for digitizing the signal. A memory (204) for storing the signal as a plurality of digitized bits (502-518), and a Digital Signal Processor (DSP) (218) for converting each of the plurality of digitized bits (502-518) into a frequency domain signal (FIG. 6) that has a plurality of frequency samples. The memory (204) stores the plurality of frequency samples corresponding to each of the plurality of digitized bits (502-518). A decoder (206, 218) decodes the plurality of communication signals from the plurality of frequency samples. The decoder (206, 218) further includes a generator (718) for generating a window (902) for measuring energy of at least one frequency sample of the plurality of digitized bits (502-518) in each of the plurality of communication signals.

Abstract: A three dimensional cellular communication system comprising a plurality of cells arranged in a multi-level environment to reduce interference and improve frequency reuse in both horizontal and vertical directions by offsetting cells stacked on different levels of the multi-level environment.

Abstract: A received phases modulated signal includes a plurality of information bits preceeded by three preamble bits. At periodic time intervals, approximately equal to one bit period, the receiver samples the signal and determines the phase angle of each bit at the sampling time. For the preamble bits, the receiver computes the phase error between the first and second preamble bits (A.sub.y -A.sub.x) and the phase error between the second and third preamble bits (A.sub.z -A.sub.y). An overall phase error (PE) is computed by taking the average of these two phase errors. To demodulate a DPSK signal, the average phase error (PE) is added to the phase angle (A.sub.i) of the present information bit. This adjusted phase angle (A.sub.i ') is then compared to the phase angle of the previous bit (A.sub.i -1) to demodulate the signal. To demodulate a PSK signal, the average phase error (PE) multiplied by D is added to the phase angle of the present information bit. This adjusted phase angle (A.sub.