
QuadFALCTM
PEF 22554 E
E1 Registers
Data Sheet
370
Rev. 1.2, 2006-01-26
Framer Receive Status Register 0
FRS0_E
Offset
Reset Value
Framer Receive Status Register 0
xx4CH
00H
Field
Bits
Type
Description
LOS
7
r
Loss-of-Signal
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 register PCD.
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
s. 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. The
bit is also set during alarm simulation and reset, if FMR0.SIM is
cleared and no alarm condition exists.
AIS
6
r
Alarm Indication Signal
The function of this bit is determined by FMR0.ALM.
FMR0.ALM = 0B: This bit is set when two or less zeros in the received
bit stream are detected in a time interval of 250 ms and the
QuadFALCTM is in asynchronous state (FRS0.LFA = 1B). The bit is
reset when no alarm condition is detected (according to ETSI
standard).
FMR0.ALM = 1B: This bit is set when the incoming signal has two or
less Zeros in each of two consecutive double frame period (512 bits).
This bit is cleared when each of two consecutive doubleframe periods
contain three or more zeros or when the frame alignment signal FAS
has been found. (ITU-T G.775)
The bit is also set during alarm simulation and reset if FMR0.SIM is
cleared and no alarm condition exists.With the rising edge of this bit an
interrupt status bit (ISR2.AIS) is set.