IDT82P20416 Integrated Device Technology, IDT82P20416 Datasheet - Page 46

• Manufacturer Part Number: IDT82P20416
• Description: 16-channel Short Haul T1/e1/j1 Line Interface Unit
• Manufacturer: Integrated Device Technology

3.5.8.2 Jitter Measurement (JM)
When the RJA is enabled in channel 0, the JM is used to measure the
positive and negative peak value of the demodulated jitter signal of the
received data stream. The bandwidth of the measured jitter is selected
by the JM_BW bit (b0, JM).
cated by the JIT_PH and JIT_PL registers, while the greatest negative
peak value monitored in the same period is indicated by the JIT_NH and
JIT_NL registers. The relationship between the greatest positive /nega-
tive peak value and the indication in the corresponding registers is:
matically. The one-second timer uses MCLK as clock reference. The
expiration of each one second will set the TMOV_IS bit (b0, INTTM) and
induce an interrupt reported by INT if not masked by the TMOV_IM bit
(b0, GCF). The TMOV_IS bit (b0, INTTM) is cleared after a ‘1’ is written
to this bit. When each one second expires, internal buffers transfer the
greatest positive/negative peak value accumulated in this one second to
the JIT_PH and JIT_PL / JIT_NH and JIT_NL registers respectively and
the internal buffers will be cleared to start a new round measurement.
The registers should be read in the next second, otherwise they will be
overwritten. Refer to Figure-29 for the process.
JM_STOP bit (b2, JM) manually. When there is a transition from ‘0’ to ‘1’
on the JM_STOP bit (b2, JM), the internal buffers transfer the greatest
positive/negative peak value accumulated in this period to the JIT_PH
and JIT_PL / JIT_NH and JIT_NL registers respectively and the internal
buffers will be cleared to start a new round measurement. The registers
should be read in the next round of jitter measurement, otherwise they
will be overwritten. Refer to Figure-30 for the process.
Functional Description
IDT82P20416
The RJA of channel 0 consists of a Jitter Measurement (JM) module.
The greatest positive peak value monitored in a certain period is indi-
Positive Peak = [JIT_PH, JIT_PL] / 16 (UIpp);
Negative Peak = [JIT_NH, JIT_NL] / 16 (UIpp).
The period is determined by the JM_MD bit (b1, JM).
When the JM_MD bit (b1, JM) is ‘1’, the period is one second auto-
When the JM_MD bit (b1, JM) is ‘0’, the period is controlled by the
46
16-CHANNEL SHORT HAUL T1/E1/J1 LINE INTERFACE UNIT
No
TMOV_IS is cleared after a '1' is written to it
buffers transfers to the JIT_PH & JIT_PL /
No
/ JIT_NH & JIT_NL registers respectively
buffers transfers to the JIT_PH & JIT_PL
JIT_NH & JIT_NL registers respectively
The greatest peak value in the internal
The greatest peak value in the internal
Read the JIT_PH, JIT_PL & JIT_NH,
Read the JIT_PH, JIT_PL & JIT_NH,
JIT_NL registers in the next second
JIT_NL registers in the next round
The internal buffers are cleared
The internal buffers are cleared
Figure-29 Automatic JM Updating
Figure-30 Manual JM Updating
Peak jitter measurement
Peak jitter measurement
Automatic JM Updating
One second expired?
A transition from '0' to
Manual JM Updating
'1' on JM_STOP ?
(TMOV_IS = 1 ?)
(JM_MD = 1)
(JM_MD = 0)
Yes
Yes
December 17, 2009
next round)
(JM_STOP
repeat the
process in
before the
the next
must be
cleared
repeat the
process in
round
same
the next
second
same