MT9074
Advance Information
Digital Milliwatt
channel is sourced from the transmit message word
in Master Control page 1.
Alarms
If the control bit ADSEQ is one, a digital milliwatt
sequence (Table 18) in T1 mode or (Table 19) in E1
mode may be transmit on any combination of
selected channels. The channels are selected by
setting bit three (TTST), in the Per Time Slot Control
Word.
The following alarms are detected by the receiver in
T1 mode. Each may generate a maskable interrupt:
•
Yellow alarm - in D4 mode there are two
possible yellow alarm signals. If control bit
D4SECY is set low, (page 1H, address 11Hb
it 1) the criteria for a yellow alarm is an
excess of ’0’s (more than 285) in bit position
2 of incoming DS0 channels during an
integration period of 1.5 milliseconds. It is
cleared after more than 3 ’1’s are detected in
bit position 2 of normal data in a 1.5
millisecond integration period. If D4SECY is
set high the secondary yellow alarm is
selected. The detection criteria becomes 2
consecutive’1’s in the Sbit position of the
12th frame. In ESF mode the alarm is set if
the pattern 0000000011111111 is received
in seven or more codewords out of ten.;
All Ones - This bit (page 3H, address 11H,
bit 3) is set if less than six zeros are received
on the incoming line data during a 3 ms
interval
Under the same control condition (ADSEQ equal to
one), the same digital milliwatt sequence is available
to replace received data on any combination of DSTo
channels. This is accomplished by setting bit two
(RRST) in the Per Time Slot Control Word for the
corresponding channel.
Bit 1 Bit 2 Bit 3 Bit 4 Bit 5 Bit 6 Bit 7 Bit 8
0
0
0
0
1
1
1
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
0
0
1
1
0
0
1
1
1
1
1
1
1
1
1
1
0
0
1
1
0
0
1
1
1
1
1
1
1
1
1
0
1
1
0
0
1
1
0
•
•
Loss of Signal - a loss of signal condition
occurs when the receive signal level is lower
than 40 dB below the nominal signal level for
Table 18 - Digital Milliwatt Pattern (T1)
at least
a
millisecond or when 192
Bit 1 Bit 2 Bit 3 Bit 4 Bit 5 Bit 6 Bit 7 Bit 8
consecutive zeros have been received. A
loss of signal condition will terminate when
than average ones density of at least 12.5%
has been received over a period of 193
contiguous pulse positions starting with a
pulse. The loss of signal is reported in the
Receive Signal Status Word - page 3,
address 16H bit 4.
0
0
0
0
1
1
1
1
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
1
0
0
1
1
0
0
1
0
0
0
0
0
0
0
0
1
0
0
1
1
0
0
1
0
0
0
0
0
0
0
0
0
1
1
0
0
1
1
0
The following alarms are detected by the receiver in
E1 mode. Each may generate a maskable interrupt:
Table 19 - A-Law Digital Milliwatt Pattern (E1)
•
•
Remote Alarm Indication (RAI) - bit 3 (A) of
the receive NFAS;
Per Channel Inversion
Alarm Indication Signal (AIS) - unframed all
ones signal for at least a double frame (512
bits) or two double frames (1024 bits);
Channel 16 Alarm Indication Signal - all ones
signal in channel 16;
Auxiliary pattern - 101010... pattern for at
least 512 bits;
Loss of Signal - a loss of signal condition
occurs when the receive signal level is lower
than 20dB or 40 dB (by setting the bit ELOS
on page 2) below the nominal signal level for
When bit six (PCI) in the Per Time Slot Control Word
is set both transmit and receive data for the selected
channel is inverted before going onto the line / DSTo
respectively.
•
•
•
Transmit Message
When bit seven (TXMSG) in the Per Time Slot
Control Word is set the data transmit in the selected
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