1997 Jun 24
13
Philips Semiconductors
Product specification
Advanced POCSAG Paging Decoder
PCD5003
Table 9
Call terminator bit identification
Note
1.
The DF bit in the call terminator is set:
a) When any call data codeword in the terminating batch was uncorrectable, while in ‘data receive’ mode.
b) When the sync word at the start of the terminating batch did not match the standard POCSAG or a
user-programmed sync word, while in ‘data fail’ mode.
Table 10
Error type identification (note 1)
Note
1.
POCSAG code allows a maximum of 3 bit errors to be detected per codeword.
BITS (MSB to LSB)
IDENTIFICATION
FT
forced call termination (1 = yes)
identifier number of last sync word
data fail mode indication (1 = data fail mode); note 1
detected error type; see Table 10; E3 = 0 in a call terminator
S3 to S1
DF
E3 to E1
E3
E2
E1
ERROR TYPE
NUMBER OF ERRORS
0
0
0
0
1
1
1
1
0
0
1
1
0
0
1
1
0
1
0
1
0
1
0
1
no errors - correct codeword
parity bit in error
single bit error
single bit error and parity error
not used
4-bit burst error and parity error
2-bit random error
uncorrectable codeword
0
1
1 + parity
1
3 (e.g.1101)
2
3 or more
Successful call termination occurs by reception of a valid
address codeword with less than 2 bit errors.
Unsuccessful termination occurs when sync word is not
detected while in ‘data fail’ mode.
It is generally possible to distinguish these two conditions
using the sync word identifier number (bits S3 to S1); the
identifier number will be non-zero for correct termination,
and zero for sync word failure.
Only when a call is received in ‘data fail’ mode and the call
is terminated before the end of the batch, is it not possible
to distinguish unsuccessful from correct termination.
Reception of message data can be terminated at any time
by transmitting a forced call termination command to the
control register via the I
2
C-bus. Any call received will then
be terminated immediately and ‘data fail’ mode will be
entered.
7.18
Receiver and oscillator control
A paging receiver and an RF oscillator circuit can be
controlled independently via enable outputs RXE and ROE
respectively. Their operating periods are optimized
according to the synchronization mode of the decoder.
Each enable signal has its own programmable
establishment time (see Table 11).
7.19
External receiver control and monitoring
An external controller may enable the receiver control
outputs continuously via an I
2
C-bus command, overruling
the normal enable pattern. Data reception continues
normally. This mode can be left by means of a reset or an
I
2
C-bus command.
External monitoring of the receiver control output RXE is
possible via bit D6 in the status register, when enabled via
the control register (D2 = 1). Each change of state of
output RXE will generate an external interrupt at
output INT.