IRT DDA-3301 User manual

3301-dda.ib.doc page 1 of 20 06/01/2004
IRT Eurocard
Types DDA-3301
G.703 Data Distribution Amplifiers
&
ZDA-3301RH
Handshake changeover assembly
I R T Electronics Pty Ltd A.B.N. 35 000 832 575
26 Hotham Parade, ARTARMON N.S.W. 2064 AUSTRALIA
National: Phone: [phone] Fax: [phone]
International: [phone] [phone]
Email: [e-mail]
Web: www.irtelectronics.com
Designed and manufactured in Australia
IRT can be found on the Internet at:
http://www.irtelectronics.com

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IRT Eurocard
Type DDA-3301
G.703 Data Distribution Amplifiers
&
ZDA-3301RH
Handshake changeover assembly
Instruction Book
Table of Contents
Section Page
General description 3
Functional diagrams 5
Technical specifications 6
Electrical characteristics of G.703 signals 9
Characteristics of signal types 10
Coding characteristics 10
G.703 data signal format 10
Description of operation 12
Handshake operation 14
Pre-installation 16
Operational safety 16
Internal adjustments 17
Installation 17
Installation in frame 17
Front & rear panel diagrams 18
Warranty & service 19
Equipment return 19
Drawing index 20
This instruction book applies to units later than S/N 0309251.

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IRT Eurocard
Types DDA-3301
G.703 Data Distribution Amplifiers
&
ZDA-3301RH
Handshake changeover assembly
General description
The DDA-3000 series of data distribution amplifiers are intended for use with data signals conforming to the ITU
Rec. G.703. Due to the fixed rates of the G.703 specification it is necessary to specify the G.703 data rate when
ordering so that the appropriate timing components, coding and levels are set in accordance with the standard.
For ease of reference the different amplifiers are called by the same designation with a suffix to indicate the rate.
This does not indicate that a product at one data rate can be readily changed to a different rate, but rather that that
they perform similar functions.
Some of the Data Distribution Amplifiers (DDA’s) in the series are primarily designed to work as stand alone
DDA’s whilst others are intended primarily for use in redundant path switching applications.
The DDA-3301 is currently available in 8, 34 and 45 Mb/s G.703 rates and is primarily intended for use in pairs
with a double width rear assembly (ZDA-3301RH) for automatic path protection applications.
Three outputs are provided at the rear of the module with an additional output for monitoring purposes on the front
panel. The primary output is controlled by relays to provide a bypass signal from the input in the event of a power
failure.
Indicators are provided on the front panel for: Data loss
AIS detect (Alarm Indication Signal)
Module in service
Module in standby.
External alarm signals are also available on the rear of the module.
Changeover inhibit and changeover request switches are provided on the front panel for use where modules are
linked in pairs for redundancy. For this configuration a special handshake connector is provided on the rear panel to
link the logic sections of two modules.
When used as a line equaliser or distribution amplifier the DDA may be housed in any of IRT’s standard Eurocard
frames. When used in pairs for handshake operation only 3 RU chassis types may be used so that the two modules
are as close together as possible. The double width rear assemblies are designed specifically for this purpose and
provide the best return loss characteristics. Cables should not be used to link two modules.
Details of frame types are available separately.
Applications:
• Stand alone cable equaliser or distribution amplifier
• Paired for redundant path protection switching
Standard features:
• Adaptive cable input equalisation
• Data regeneration & re-clocking
• Monitor facility
• Power fail bypass facility
• External alarms and bypass
• Redundancy handshake facility
• IRT Eurocard construction compatible with other IRT Eurocard modules and frames
• Dual power supply operation

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Equipment provided:
Standard: DDA-3301/XX Data distribution amplifier module.
(Where XX is the G.703 data rate)
ZDA-3301 Rear assembly for stand alone DDA-3301.
Accessories available:
ZDA-3301RH Double rear assembly for handshake: Connects two adjacent DDA-3301’s for automatic
changeover of all three outputs in the event of a fault
being detected. Note that the ZDA-3301RH
supersedes the earlier ZDA-3101RH.

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Functional diagrams
J 3
Handshake diagram 2 x DDA-3301
J 2
J 4
INPUT
RELAY
K 1.3 RELAY
K 1.2 OUTPUTS
DDA SIGNAL
PROCESSING
RELAYS
K 3, RL 1 & RL 2
INPUT
RELAY
K 1.3 RELAY
K 1.2
DDA SIGNAL
PROCESSING
RELAYS
K 3, RL 1 & RL 2
INPUT
J 1
RELAY
K 1.3
RELAY
K 1.2
OUTPUTS
RELAY
RL 1 J 3
RECLOCKING
AIS DETECTION
DATA FAIL
DETECTION
MAIN/SBY LOGIC
FOR K 3
CLOCK
&
DATA
RECOVERY
EQUALISER
Relay K 1 = Power fail bypass.
Relay K 3 = Magnetic latching Main/Sby.
CLOCK
+ MARKS
- MARKS
MON
.
Block diagram DDA-3301- Signal path
RELAY
K 3 J 2
RELAY
RL 2 J 4

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Technical specifications
DDA-3301/8:
Conforms to CCITT G.703 8448 Kb/s – see Electrical characteristics of G.703 signals.
Input:
Type Transformer coupled.
Impedance 75 Ωterminated.
Cable equalisation Automatic.
0 - 6 dB at 4,224 KHz. Components set for Beldin YR23769 cable.
Outputs:
Type Transformer coupled.
Number 3 switched, regenerated, reclocked outputs located on rear connection
assembly and one located on front panel.
Impedance 75 Ωsource terminated.
DDA-3301/34:
Conforms to CCITT G.703 34368 Kb/s – see Electrical characteristics of G.703 signals.
Input:
Type Transformer coupled.
Impedance 75 Ωterminated.
Cable equalisation Automatic.
0 - 12 dB at 17,184 KHz. Components set for Beldin YR23769 cable.
Outputs:
Type Transformer coupled.
Number 3 switched, regenerated, reclocked outputs located on rear connection
assembly and one located on front panel.
Impedance 75 Ωsource terminated.
DDA-3301/45:
Generally in accord with CCITT G.703 44736 Kb/s – see Electrical characteristics of G.703 signals.
Input:
Type Transformer coupled.
Impedance 75 Ωterminated.
Equalisation Automatic for up to 400 m of Belden 8281 equivalent.
Outputs:
Type Transformer coupled.
Number 3 switched, regenerated, reclocked unshaped outputs located on rear
connection assembly and one located on front panel.
Impedance 75 Ωsource terminated.
Electrical Characteristics:
Cable Type Coaxial
Impedance 75 Ω
Signal level 1.0 V
Pulse Shape Unshaped, scaled from fig. 17/G.703
Nominal pulse width 14.55 ns
Code conversion B3ZS
Jitter at input port § 3 of recommendation G.823
Jitter at output port § 2 of recommendation G.823
Return loss at input ports:
860 KHz to 1720 KHz 12 dB
1720 KHz to 34368 KHz 18 dB
34368 KHz to 51550 KHz 14 dB

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Common data:
(Applies to all versions)
Controls & alarms:
Input:
External changeover request A ground applied to this input will emulate the operation of the front panel switch
“Change Request”
Outputs:
Bypass Contact closure to ground if power has failed
General alarm Contact closure to ground if
a. Data Loss is detected OR
b. AIS is detected AND the AIS disable link (LK 1) is not installed
AIS detection is defined as at least 2048 consecutive data “1”s
Data Loss is defined as less than 120 data “1”s in 512 G.703 data rate clock
periods
Connectors: Data: BNC
Alarm: Krone LSA plus
Indicators: DC power
Data loss
AIS detect
Module in service
Module in standby
Power requirements 28 Vac CT (14-0-14) or ±16 Vdc
Power consumption 170 mA. (5.5 VA)
Temperature range 0 - 50° C ambient
Mechanical Suitable for mounting in IRT 19" rack chassis types with input output and power
connections on the rear panel
Finish: Front panel: Grey background, black lettering & red IRT logo
Rear assembly: Detachable silk-screened PCB with direct mount connectors to Eurocard and
external signals
Dimensions 6 HP x 3 U x 220 mm IRT Eurocard
Standard accessories Rear connector assembly

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ZDA-3301RH Technical specifications
Controls & alarms:
Input:
External changeover request A ground applied to this input will emulate the operation of the front panel
switch “Change Request”.
Outputs:
Bypass Contact closure to ground if power has failed.
General Alarm Contact closure to ground if
a. Data Loss is detected OR
b. AIS is detected AND the AIS disable link (LK 1) is not installed.
AIS detection is defined as at least 2048 consecutive data “1”s.
Data Loss is defined as less than 120 data “1”s in 512 G.703 data rate clock
periods.
In Service (Main) Path Indication: Transistor switch to ground if card is Main (if DA version is equipped).
Connectors: Data: BNC.
Alarm: Krone LSA plus.
In Service (Main) Path: Krone LSA plus.
Changeover logic:
A changeover to the companion module will occur under any of the following conditions:
Loss of input signal
AIS detection alarm (provided AIS is not disabled by link LK 1)
Loss of power
In all of the above cases switching will only occur if
companion module is able to provide an output free of the same defects and
changeover inhibit switch is not activated on either module.
Priority logic:
The priority switching in normal mode follows non-reverting logic, which dictates:
In the event of failure of main then standby DDA will assume control and become Main causing the failed
path DDA to become Standby.
This implies that when the failed path is restored that it will remain as Standby and not become Main unless either a
failure of Main occurs or a manual changeover is requested.
Power on reset.
When power is applied to the pair, the power on reset signal will set the module which was last enabled as Main as
Main and the other module will be forced to act as Reserve.
When power is applied to a pair for the first time it may be necessary to force the desired module to become main by
pressing the Change Request button on the front panel of the desired module. The Main module will be indicated by
the In Service LED lighting on the front panel.

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Electrical characteristics of G.703 signals:
Electrical characteristics CCITT G.703 2048 Kb/s:
Pair each direction One coaxial pair.
Test load impedance 75 Ωresistive.
Signal level 2.37 V.
Nominal pulse width 244 ns.
Code conversion HDB3.
Pulse shape Fig. 15/G.703.
Jitter at input port § 3 of recommendation G.823.
Jitter at output port § 2 of recommendation G.823.
Return loss at input ports:
51 KHz to 102 KHz 12 dB.
102 KHz to 2048 KHz 18 dB.
2048 KHz to 3072 KHz 14 dB.
Electrical characteristics CCITT G.703 8448 Kb/s:
Pair each direction One coaxial pair
Test load impedance 75 Ωresistive
Signal level 2.37 V
Nominal pulse width 59 ns
Code conversion HDB3
Pulse shape Fig. 16/G.703
Jitter at input port § 3 of recommendation G.823
Jitter at output port § 2 of recommendation G.823
Return loss at input ports:
211 KHz to 422 KHz 12 dB
422 KHz to 8448 KHz 18 dB
8448 KHz to 12672 KHz 14 dB
Electrical characteristics CCITT G.703 34368 Kb/s:
Cable Type Coaxial
Impedance 75 Ω
Signal level 1.0 V
Nominal pulse width 14.55 ns
Code conversion HDB3
Pulse shape Fig. 17/G.703
Jitter at input port § 3 of recommendation G.823
Jitter at output port § 2 of recommendation G.823
Return loss at input ports:
860 KHz to 1720 KHz 12 dB
1720 KHz to 34368 KHz 18 dB
34368 KHz to 51550 KHz 14 dB
Electrical characteristics CCITT G.703 Shaped 44736 Kb/s:
Cable Type Coaxial
Impedance 75 Ω
Signal level
Power at 22368 KHz +1.8 dBm to +5.7 dBm.
Power at 44736 KHz >20 dBm below power at 22368 KHz.
Code conversion B3ZS
Pulse shape Fig. 14/G.703
Electrical characteristics CCITT G.703 Unshaped 44736 Kb/s:
Cable Type Coaxial
Impedance 75 Ω
Signal level 1.0 V
Pulse Shape Unshaped, scaled from fig. 17/G.703
Nominal pulse width 14.55 ns
Code conversion B3ZS
Jitter at input port § 3 of recommendation G.823
Jitter at output port § 2 of recommendation G.823
Return loss at input ports:
860 KHz to 1720 KHz 12 dB
1720 KHz to 34368 KHz 18 dB
34368 KHz to 51550 KHz 14 dB

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Characteristics of signal types
Coding characteristics - G.703:
The HDB3 (High Density Bi-polar of order 3) code as defined in G.703 for 34,368 Kb/s is as follows:
Binary 1 bits are represented by alternate positive and negative pulses and binary 0 bits by spaces. Exceptions
are made when strings of successive 0 bits occur in the binary signal.
Each block of 4 successive zeros is replaced by 000V or B00V where B is an inserted pulse of the correct
polarity and V is an inserted pulse violating the polarity rule. The choice of 000V or B00V is made so that
the number of B pulses between consecutive V pulses is odd so that successive V pulses are of alternate
polarity and so no DC component is introduced.
The B3ZS (Bipolar with Three Zero Substitution) (Also designated HDB2 - High Density Bi-polar of order 2) code
as defined in G.703 for 44,736 Kb/s is as follows:
Binary 1 bits are represented by alternate positive and negative pulses and binary 0 bits by spaces. Exceptions
are made when strings of successive 0 bits occur in the binary signal.
Each block of 3 successive zeros is replaced by 00V or B0V. The choice of 00V or B0V is made so that the
number of B pulses between consecutive V pulses is odd, so that successive V pulses are of alternate polarity
and so no DC component is introduced.
G.703 data signal format.
The following waveforms are intended to give some idea of the type of signal at various points in the DDA when in
operation. They are not intended as accurate portrayals of either voltage levels or timing.
It can be seen that the original signal has both positive and negative going pulses. This format is used so that the
signal does not rely on DC levels. To preserve the AC nature of the signal a coding system is used to ensure that a
succession of either ‘1’s or ‘0’s in the original data does not produce a DC output. The coding system varies
according to the type of G.703 signal (See specifications for each module and Coding characteristics above.)
It can be seen that the cable effected signal bears little resemblance to the original signal and due to the high
frequency attenuation looks more like a noisy analogue signal than a digital signal. The input equaliser circuit in the
DDA enhances the high frequency response and detects the rate of change of the signal to produce a squared up
signal with fast rise and fall times suitable for processing and re-clocking.
The signal is separated into +ve and -ve mark signals as shown. The relative timing of these signals must be closely
maintained or the final re-clocked output signal will not be accurate.
The re-clocking circuit acts on each of the +ve and -ve mark signals by detecting the data rate with a phase locked
loop which has a sufficiently long flywheel time to maintain the clock frequency in the presence of the maximum
length ‘0’ data signal.
The re-clocked +ve and -ve mark signals are fed to separate output drivers for each output where they are
recombined in the output transformers resulting in an output signal as shown which is the same as the original
signal.

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Original signal
Cable effected signal
Equalised signal
Positive mark signal
Negative mark signal
Output signal

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Description of operation
See block diagrams commencing on page 5 and schematic diagrams at rear of this manual.
Unless specified, the following description applies to all G.703 data rates.
Input:
The G.703 input signal is connected to the input circuit of the amplifier.
If no power is present, and the amplifier was active before the power was removed, then the signal will be directed
to the output connector via K 1 and K 3. When power is applied the K 1 relays operate and switch the signal via the
amplifier to the K 3 relay and thence the output connectors.
In this power fail mode, the connection from input to output is passive and so only one output can be connected.
The K 3 relay is of the bi-stable magnetic latching type and so will only change state when an imbalance of drive
occurs between the set and reset coils. The K 3 relay is operated under the control of the logic processor main select
via transistor driver Q 8 to the set coil and released by any external signal present on the pin 9 status input of the
handshake connector to the reset coil.
When power is applied to the DDA, the logic circuit will cause the K 3 relay to be set. If two DDA’s are connected
in handshake configuration, one of the two will take control first and become the main amplifier causing the other to
become the standby.
Either module can be made main by pressing the change request button on the front panel of the required module
provided that no alarms are present. An external changeover request may also be made via pin 3 of SK 2
alarm/control connector on the rear panel provided that the changeover inhibit switch on the front panel is not in the
inhibit position.
When the K 3 relay is in the reset position the input path from the input connector and the K 1 relay is terminated in
75 Ωto preserve the loading on the input.
Active path:
Input switching & equaliser:
The signal from the K 1a relay connects to the input transformer and automatic line equalisation circuit consisting of
transistors Q 1 to Q 6. The purpose of this equaliser is to restore both the signal level and the leading and trailing
edges of the digital signal so that signal jitter is not introduced when the clock signal is derived in the subsequent
stage.
+ve & -ve mark signals and clock generator:
The equalised signal is coupled to the following stages by transformer T 2. This has two secondary windings to
translate the positive and negative going components of the signal to a positive format for processing by standard
single supply logic circuits in the following stages. The two signals are identified as the +ve and -ve mark signals
and remain separate until the final output driver stage.
Both the logic and reclocking circuits require a synchronous clock signal. The clock is an oscillator formed by U 3 a,
b & c and is re-triggered to keep time by a signal extracted from both the +ve or -ve mark signals (OR gate U 3 d).
The clock signal is retarded by delay line DLY prior to being used in the main processing logic and reclocking
circuit in order to provide the optimum timing at the reclocking point.

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Logic processing, reclocking and AIS detection:
The main logic processing, reclocking, error detection and operational interfacing are all performed by logic circuits
within U 4, which is a custom-programmed large scale logic array. The internal logic and functions of this IC are too
complex to describe in detail and the following is intended as a guide to function only.
Data loss detection:
Valid data is deemed to be present at the module input when 120 or more data pulses have been received in 512
nominal clock periods at the G.703 data bit rate specified for the DDA. In order for the data pulse to be counted,
more than 60% of the minimum anticipated data pulse must be present.
If less than 120 data pulses are counted over a period of 512 clock pulses then the data signal is deemed to be invalid
and the data loss flag is set.
If the area of a given pulse is less than 60% of the minimum anticipated (or acceptable) data pulse, after line
equalisation and shaping, then that pulse is not considered as a valid input to the count.
In any of these cases the Data Loss LED on the front panel of the module will light and the general alarm relay
output will be activated connecting the general alarm output contact to ground.
AIS detection:
The data processor will detect an incoming AIS (Alarm Indication Signal) (a series of >2048 1’s) and will set the
AIS flag and the general alarm relay output will be activated connecting the general alarm output contact to ground.
Note however that when data errors or no data is detected that the DDA-3301 does not generate an outgoing AIS
data stream to the data outputs.
The AIS alarm system may be disabled by a link on the main board LK 1. This prevents the AIS detection from
operating the automatic changeover function when used in handshake configuration and prevents AIS from setting
the general alarm output. The AIS detection circuit will, however, still provide AIS indication, on the front panel
LED, if AIS is detected.
The AIS disable link does not effect the general alarm being activated by data or signal loss as described above.
Power on reset:
When power is applied to the unit, U 6 generates a power on reset signal. This signal causes the processing circuit to
examine its current status and connections and restore operation to its state prior to power failure.
If the DDA is connected for stand-alone operation all alarms will be reset and normal operation will resume. If an
AIS signal is present on the data input or data is outside the prescribed limits outlined above then the general alarm
will be activated after the normal detection period has elapsed from the P.O.R. signal being initiated.
For operation in handshake mode see Handshake operation description.
ARA in & urgent alarm out.
These facilities are not enabled at this time.
Data signal output drivers.
The reclocked +ve and -ve mark signals are bussed to output drivers U 7 to 10.
Each output driver consists of three inverters operating in parallel in order to obtain a high current output capability
for driving the output transformer without stressing any individual amplifier.
Diodes are connected across the transformer primary to ground and the inverter output to +5V to prevent any back
EMF from causing damage to the drivers. The resistors between the output drivers and the output transformer set the
correct output operating pulse amplitude to ±1 V measured at the output connectors.
Note that the Mon. Output on the front panel of the module is obtained in the same manner as the outputs on the rear
of the module.

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Handshake operation:
Purpose:
Handshake interconnection is required when two circuits are to be operated in 1:1 protection switching mode to
provide a continuous signal output in the event of failure of the primary signal path.
Priority logic:
For this mode to be employed it is necessary to provide two programme feeds which are designated as the Main and
Standby paths.
The priority switching in normal mode follows non-reverting logic, which dictates:
In the event of failure of main then standby DDA will assume control and become Main causing the failed
path DDA to become Standby.
This implies that when the failed path is restored that it will remain as Standby and not become Main unless either a
failure of Main occurs or a manual changeover is requested.
Changeover logic:
A changeover to the companion module will occur under any of the following conditions:
Loss of input signal
AIS detection alarm (provided AIS is not disabled by link LK 1)
Loss of power
In all of the above cases switching will only occur if:
the companion module is able to provide an output free of the same defects AND
the changeover inhibit switch is not activated on either module.
Connections:
Handshake interconnection should only be made using either the ZDA-3301RH or the earlier ZDA-3101RH
handshake double rear assembly.
This rear assembly makes all the necessary connections for both logic and data signals when two DDA’s are inserted
side by side in a 3 RU frame.
Individual alarm outputs are provided for each module.
Detailed operational description:
Connections for handshake (paired) operation of two DDA-3301’s are shown in the following diagram.
Inputs & outputs:
The two modules are supplied with signals from separate paths to their input connectors on the rear of the module.
For the purposes of description these are designated as the main and reserve inputs although they may be of equal
standing.
ZDA-3301RH handshake connections
(Three switched outputs)
Presen
t
8K2
SIGNAL
&
LOGIC
PROCESSING
4K7
+5
+12
Present
Loop
Status
Main select
4K7 4K7
4K7 8K2
+12
4K7
10R
K 3/2
K 3/1
10R
K 1a
EQUIP.
8K2
SIGNAL
&
LOGIC
PROCESSING
4K7
+12
Status Main select
4K7
4K7
4K7
+5
Loop
4K7
10R
K 3/2
K 3/1
+12
10R
K 1a
EQUIP.
RL 1 RL 1
J4
8K2
Main Input Reserve Input
Outputs
K 1b
75R
K 3 K 1b
J2
75R
K 3
J3
In Service Indicator In Service Indicator

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Logic connections:
All required logic connections are made by tracks on the double width PCB. Automatic operation is immediately
initiated when two modules are plugged into this type of rear assembly.
No external connections are required, but external alarm connections are available from each module for use if
desired. Additionally, each module has a connection for an external Make Main control for remote DA selection.
Handshake mode detection:
Two data lines are present on the handshake connector to indicate to each module that it is to operate in handshake
mode.
The Loop signal on pin 16a is connected to ground when another module is connected and the Present signal on pin
16b detects the presence of power on the alternate module.
If the Loop signal is not connected to ground then all handshake operations are inhibited.
If the loop signal is at ground indicating the presence of an alternate module and if power is present on both modules
then normal handshake operation is permitted. If the Present signal indicates that power is lost on the alternate
module then the module with power will take control and become Main.
Power on reset.
When power is applied to the pair the power on reset signal will attempt to reset both modules. However, as only
one module can be Main, the logic processor checks for handshake operation and if detected then the module which
was last enabled as Main will take control as Main and the other module will be forced to act as Reserve.
This memory capability is due to the latching nature of the K 3 relay, which will cause the Main and Reserve paths
to be maintained even in the absence of power.
The only exception to this rule is when power is applied to a pair for the first time that they are coupled in
handshake mode. In this special case both modules will initially have their K 3 relays in the active path condition
and so both will attempt to become Main. As the P.O.R. signal for each module will be slightly different for any two
modules, one will reach its operating mode first and will force the other module to immediately change to become
Reserve.
As the selection of which module becomes Main is cannot be determined before installation it may be necessary to
force the desired module to become main by pressing the Change Request button on the front panel of the desired
module. The Main module will be indicated by the In Service LED, on the front panel, lighting.
Automatic changeover:
An automatic changeover is initiated whenever the power fails on Main and not on Reserve or when a general alarm
is initiated on Main (indicating either loss of input signal or AIS indication if the AIS is enabled) and the Change
Inhibit switch is not active on either module.
In either case, the Main Status line will go from LO to HI. The companion module, on detecting this change, will
switch its Main Select line to HI. The K 3/1 relay driver then activates the relay (hence becoming Main) and sends
the Status line to the first module LO confirming the change and preventing that module from attempting to become
Main again.
Manual changeover:
A manual changeover is initiated by pressing the Change Request button on the front of the module that is required
to become Main.
The mechanism of the change is similar to the automatic changeover described above except that it is initiated by
the module requesting that it become Main. This forces the Status line to the other module to LO and it immediately
responds to become Reserve.
Alarm and external changeover connections:
Two Krone type connectors are provided on the rear panel providing the following for each of the modules:
Pin 1 K 1 relay status - connection to ground indicates module is in bypass mode (loss of
power).
2 K 2 relay status - connection to ground indicates a general signal alarm.
3 External changeover request - connection to ground will make this module Main in
handshake mode.
4 Ground.
A third Krone type connector (SK3) provides remote status of which unit is In Service (Main):
Pin 1 Connection to ground indicates that module 1 is the In Service (Main) module.
2 Connection to ground indicates that module 2 is the In Service (Main) module.
3 Ground.
Note that SK3 is not provided on the earlier ZDA-3101RH rear assembly.

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Pre-installation:
Handling:
This equipment may contain or be connected to static sensitive devices and proper static free handling precautions
should be observed.
Where individual circuit cards are stored, they should be placed in antistatic bags. Proper antistatic procedures
should be followed when inserting or removing cards from these bags.
Power:
AC mains supply: Ensure that operating voltage of unit and local supply voltage match and that
correct rating fuse is installed for local supply.
DC supply: Ensure that the correct polarity is observed and that DC supply voltage is maintained
within the operating range specified.
Earthing:
The earth path is dependent on the type of frame selected. In every case particular care should be taken to ensure
that the frame is connected to earth for safety reasons. See frame manual for details.
Signal earth: For safety reasons a connection is made between signal earth and chassis earth. No attempt should be
made to break this connection.
Operational Safety:
WARNING
Operation of electronic equipment involves the use of voltages and currents that may
be dangerous to human life. Note that under certain conditions dangerous potentials
may exist in some circuits when power controls are in the OFF position.
Maintenance personnel should observe all safety regulations.
Do not make any adjustments inside equipment with power ON unless proper
precautions are observed. All internal adjustments should only be made by suitably
qualified personnel. All operational adjustments are available externally without the
need for removing covers or use of extender cards.

3301-dda.ib.doc page 17 of 20 06/01/2004
Internal adjustments
The only internal adjustment that may be made by the user is link LK 1, which may be set to disable AIS detection if
required.
This module uses a programmable logic device as the main processing circuit. This device must be correctly
programmed is only obtainable through IRT. No attempt should be made to substitute other devices or to
programme a similar device as this could cause extensive damage to the module.
Installation
Installation in frame or chassis:
See details in separate manual for selected frame type.
G.703 data connections - stand alone operation:
Connect the input and as many output connections as required.
Only good quality 75 Ohm connectors and cable should be used. The use of 50 Ohm BNC connectors may cause
serious reflection problems with G.703 signals, causing data errors.
In general cable runs should be kept as short as possible and should not exceed 200 metres for reliable error free
operation.
G.703 data connections - handshake operation:
See separate section on handshake operation.
Alarm and external changeover connections:
A Krone type connector is provided on the rear panel of the module providing the following:
Pin 1 K 1 relay status - connection to ground indicates module is in bypass mode (loss of
power).
2 K 2 relay status - connection to ground indicates a general signal alarm.
3 External changeover request - connection to ground will make this module Main in
handshake mode.
4 Ground.

3301-dda.ib.doc page 18 of 20 06/01/2004
ZDA-3301
1
2
3
4
2SK 2
1J 2
MODULE 1
1J 3
MODULE 2
1J 4
1
2
3
4
2J 1 1J 1
INPUT
MODULE 2 INPUT MODULE 1
1SK 2
1
2
3
SK 3
Front & rear panel diagrams
The following front panel and rear assembly drawings are not to scale and are intended to show relative positions of
connectors, indicators and controls only.
3301
1
2
3
4
SK 2 INPUT
O/P 1
O/P 2
O/P 3
MON.
ALLOW
INHIBIT
REQUEST
AIS
STANDBY
CHANGE
DATA
LOSS
IN
SERVICE
DDA-3301
N140

3301-dda.ib.doc page 19 of 20 06/01/2004
Warranty & service
Equipment is covered by a limited warranty period of three years from date of first delivery unless contrary
conditions apply under a particular contract of supply. For situations when “No Fault Found” for repairs, a
minimum charge of $A100.00 will apply, whether the equipment is within the warranty period or not.
Equipment warranty is limited to faults attributable to defects in original design or manufacture. Warranty on
components shall be extended by IRT only to the extent obtainable from the component supplier.
Equipment return:
Before arranging service ensure that the fault is in the unit to be serviced and not in associated equipment. If
possible, confirm this by substitution.
Before returning equipment contact should be made with IRT or your local agent to determine whether the
equipment can be serviced in the field or should be returned for repair.
The equipment should be properly packed for return observing antistatic procedures.
The following information should accompany the unit to be returned:
1. A fault report should be included indicating the nature of the fault
2. The operating conditions under which the fault initially occurred.
3. Any additional information which may be of assistance in fault location and remedy.
4. A contact name and telephone and fax numbers.
5. Details of payment method for items not covered by warranty.
6. Full return address.
7. For situations when “No Fault Found” for repairs, a minimum charge of $A100.00 will apply, whether
the equipment is within the warranty period or not.
Please note that all freight charges are the responsibility of the customer.
The equipment should be returned to the agent who originally supplied the equipment or, where this is not
possible, to IRT direct as follows.
Equipment Service
IRT Electronics Pty Ltd
26 Hotham Parade
ARTARMON
N.S.W.2064
AUSTRALIA
Phone: [phone] Fax: [phone]
Email: [e-mail]

3301-dda.ib.doc page 20 of 20 06/01/2004
Drawing index
Drawing # Sheet # Description
804361 1 DDA-3301/34 34 Mb DA schematic part 1.
804361 2 DDA-3301/34 34 Mb DA schematic part 2.
804362 DDA-3301/45 45 Mb distn amplifier parts list
804807 ZDA-3301RH handshake rear assembly schematic