A CDMA communication apparatus includes a system of dual transmission
spread processing circuits wherein switching control of one of the
transmission spread processing circuits from an operating system to a
standby system is performed momentarily by software while miniaturization
and reduction in cost of the apparatus are assured. A spread processing
circuit of each of dual transmission spread processing circuits is divided
into two sections of an operating system spread processing section and a
standby system spread processing section. Spread signals processed by the
operating system spread processing section and the standby system spread
processing section are addition synthesized by a first addition synthesis
section and a second addition synthesis section separately from each
other. An addition selection section for selecting whether or not
operating system spread signals and standby system spread signals should
be addition synthesized is provided in each of the transmission spread
processing circuits. The addition selection section is directly controlled
with a failure detection signal from a failure detection section of the
other one of the dual transmission spread processing circuits.
