FALC
56
PEF 2256 H/E
T1/J1 Registers
User’s Manual
Hardware Description
428
DS1.1, 2003-10-23
Framer Receive Status Register 0 (Read)
LOS
Loss-of-Signal (Red Alarm)
Detection:
This bit is set when the incoming signal has “no transitions“ (analog
interface) or logical zeros (digital interface) in a time interval of T
consecutive pulses, where T is programmable by PCD register:
Total account of consecutive pulses: 16 < T < 4096.
Analog interface: The receive signal level where “no transition” is
declared is defined by the programmed value of LIM1.RIL(2:0).
Recovery:
Analog interface: The bit is reset in short-haul mode when the
incoming signal has transitions with signal levels greater than the
programmed receive input level (LIM1.RIL(2:0)) for at least M pulse
periods defined by register PCR in the PCD time interval. In long-haul
mode additionally bit RES.6 must be set for at least 250 μs.
Digital interface: The bit is reset when the incoming data stream
contains at least M ones defined by register PCR in the PCD time
interval.
With the rising edge of this bit an interrupt status bit (ISR2.LOS) is set.
For additionally recovery conditions refer also to register LIM2.LOS1.
The bit is set during alarm simulation and reset if FRS2.ESC = 0, 3,
4, 6,7 and no alarm condition exists.
AIS
Alarm Indication Signal (Blue Alarm)
This bit is set when the conditions defined by bit FMR4.AIS3 are
detected. The flag stays active for at least one multiframe.
With the rising edge of this bit an interrupt status bit (ISR2.AIS) is set.
It is reset with the beginning of the next following multiframe if no
alarm condition is detected.
The bit is set during alarm simulation and reset if FRS2.ESC = 0, 3,
4, 7 and no alarm condition exists.
7
0
FRS0
LOS
AIS
LFA
RRA
LMFA
FSRF
(4C)