Service manual

1-20 June 21, 2004
GENERAL NP88 FLEX
Paging Coding Schemes
FLEX Paging Format, Code, and Code Capacity
AFLEXtransmissioncycleis4minuteslonganddividedinto128frames,numbered
from 0 to 127. Fifteen FLEX cycles (numbered 0 through 14) occur in one hour.
A single FLEX frame is transmitted at 1.875 seconds per frame (32 frames per
minute) and consists of 1 sync block followed by 11 frame blocks (numbered
0 through 10). The structure of a FLEX frame is shown in Figure 1-8.
Aframesyncblockprovides timing and frame information and is divided into three
parts:
• sync 1
• frame info
• sync 2
The sync 1 portion is transmitted at 1600 bps providing frame timing and 1600 bps
symbol timing. Sync 1 also specifies frame timing as 1600, 3200, or 6400 bps.
The frame information word contains the frame and cycle numbers, indica tions of
low traffic (address field does not extend past block 0), and a 4-bit check character
to ensure quality of the received information.
Thesync2portionoftheframeisdesignedtoprovidesynchronizationattheframe’s
block speed allowing proper demultiplexing and decoding of the message blocks.
Paging Coding Schemes
Figure 1-8. FLEX Paging Format