Using the Internal Modem 7-21
Writer: Carey Gregg Saved by: Rebecca Wiggins Saved date: 02/06/98 11:07 AM
Part Number: 314932-001 File name: Ch07.doc
Dead Spots and Dropouts
Dead spots are areas where cellular network radio signals cannot
be received. Dropouts occur when the mobile user temporarily
passes through an area (dead spot) where the radio signal is
blocked or reduced.
Bandwidth Limitations
A large portion of the cellular voice channel is reserved for out-of-
band signaling, therefore reducing the available bandwidth on the
cellular network. Instead of having a flat response like the
noncellular bandwidth, the cellular network processes the voice
signal to improve quality. These bandwidth limitations can result
in distortion and signal loss.
Signal Strength
Distance and obstacles can cause out-of-phase reflected signals
that result in a loss of signal strength, resulting in the loss of an
entire signal interval, or baud.
Network Voice Compression
On some networks, the link between the cell site and the MTSO
(Mobile Telephone Switching Office) can employ compression
techniques that work for voice, but can limit data transfer speed.
Low Signal Strength
Because of either distances or obstacles, the radio signal strength
from a cell site may not be strong or stable enough to provide a
reliable connection for either voice or data communications.
Unavailable Channel
No channel is available for use.