Service manual

June 21, 2004 1-17
NP88 FLEX GENERAL
Theory of Operation
Theory of Operation
The NP88 FLEX pagers consists of a radio frequency (RF) receiver section
and a mi crocomputer-controlled decoder section. A message is received via an RF
carrier that is frequency modulated by a coded binary sequence utilizing FLEX
paging protocol.
The circuitry in the receiver performs the RF to intermediate frequency (IF)
conversion.Thereceiverthenpassesthefrequencydemodulatedaudiosignaltothe
decoder, which contains the customized analog and digital circuitry necessary to
decode the page information. Additionally, the decoder contains other support
circuitry to capture switch closures, provide tone and visual alerts, and display
pages and other user information on the LCD. Refer to the appropriate receiver
section for further specifics about each signal frequency.