LG ipLDK-60 User manual

ipLDK-60 SERVICE MANUAL
DIGITAL KEY TELEPHONE SYSTEM
DIGITAL KEY TELEPHONE SYSTEM
SERVICE MANUAL
MODEL : ipLDK-60

ipLDK-60 SERVICE MANUAL
DIGITAL KEY TELEPHONE SYSTEM
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Table of Contents
SECTION 1. GENERAL DESCRIPTION..........................................................................................................1
1.1 SYSTEM CONNECTION DIAGRAM ............................................................................................................. 2
1.2 SPECIAL ATTENTION OF NOTICE ............................................................................................................... 3
1.3 SYSTEM FEATURES................................................................................................................................. 3
1.4 SYSTEM SPECIFICATIONS ........................................................................................................................ 4
1.4.1 General specifications................................................................................................................. 4
1.4.2 Environment Specification........................................................................................................... 5
1.4.3 System Capacity ......................................................................................................................... 5
1.5 SYSTEM CONFIGURATION........................................................................................................................ 6
1.5.1 System Configuration.................................................................................................................. 6
1.5.2 System Components................................................................................................................... 7
SECTION 2. SYSTEM OPERATION THEORY................................................................................................9
2.1 SYSTEM ARCHITECTURE ......................................................................................................................... 9
2.1.1 General Description .................................................................................................................... 9
2.1.2 Instrument Types......................................................................................................................... 9
2.1.3 Capacity Limitations .................................................................................................................. 10
2.2 SWITCHING............................................................................................................................................11
2.2.1 Back plane Architecture .............................................................................................................11
2.2.2 Signaling Channels ....................................................................................................................11
2.3 ADMINISTRATION................................................................................................................................... 12
2.3.1 General Description .................................................................................................................. 12
2.3.2 System Generic Memory........................................................................................................... 12
2.3.3 Operating Memory .................................................................................................................... 12
2.3.4 Customer Database Memory .................................................................................................... 12
2.3.5 System Resources .................................................................................................................... 12
2.4 CALL PROCESSING ............................................................................................................................... 14
2.4.1 Internal Call Types..................................................................................................................... 14
2.4.2 Outside Call Types .................................................................................................................... 14
2.4.3 Conferencing............................................................................................................................. 15
SECTION 3. CIRCUIT DESCRIPTION...........................................................................................................16
3.1 MAIN BOARD UNIT WITH CO.................................................................................................................. 16
3.1.1 General ..................................................................................................................................... 16
3.1.2 Block Diagram & Circuit Description ......................................................................................... 17
3.1.3 Meaning of Connectors, Switches and LEDs............................................................................ 33
3.2 EMBU (EXPANSION MAIN BOARD UNIT) ................................................................................................ 39
3.2.1 General ..................................................................................................................................... 39
3.2.2 Block Diagram........................................................................................................................... 39
3.2.3 Circuit description...................................................................................................................... 40
3.2.4 Meaning of Connectors and LEDs ............................................................................................40
3.3 CHB308 AND CSB316 ......................................................................................................................... 43
3.3.1 General ..................................................................................................................................... 43

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3.3.2 Block Diagram........................................................................................................................... 43
3.3.3 Circuit description...................................................................................................................... 44
3.3.4 Meaning of Connectors ............................................................................................................. 49
3.4 SLIB8 (SINGLE LINE INTERFACE BOARD-8PORT) ................................................................................... 53
3.4.1 General ..................................................................................................................................... 53
3.4.2 Block Diagram........................................................................................................................... 53
3.4.3 Circuit description...................................................................................................................... 53
3.4.4 Meaning of Connectors ............................................................................................................. 54
3.5 E1HB8(E1R2 DIGITAL TRUNK &8HYBRID BOARD) ................................................................................ 55
3.5.1 General ..................................................................................................................................... 55
3.5.2 Block Diagram........................................................................................................................... 55
3.5.3 Circuit Description ..................................................................................................................... 56
3.5.4 Connectors, Modular jacks and LEDs....................................................................................... 69
3.6 VMIU/AAFU ........................................................................................................................................ 73
3.6.1 General ..................................................................................................................................... 73
3.6.2 VMIU/AAFU Block Diagram ...................................................................................................... 73
3.6.3 Functional description ............................................................................................................... 73
3.6.4 Circuit description...................................................................................................................... 74
3.6.5 Connector.................................................................................................................................. 75
3.7 MODU (MODEM UNIT).......................................................................................................................... 76
3.7.1 General ..................................................................................................................................... 76
3.7.2 Block Diagram & Description .................................................................................................... 76
3.8 CMU50PR /CMU12PR ....................................................................................................................... 77
3.8.1 CMU50PR (Call Metering-50Hz and Polarity Reversal Detection Unit) .................................... 77
3.8.2 CMU12PR (Call Metering-12KHz and Polarity Reversal Detection Unit).................................. 77
3.8.3 Block diagram ........................................................................................................................... 78
3.8.4 Circuit description...................................................................................................................... 79
3.9 VOICE OVER INTERNET PROTOCOL INTERFACE MODULE(VOIB).............................................................. 81
3.9.1 General ..................................................................................................................................... 81
3.9.2 Block Diagram........................................................................................................................... 82
3.9.3 Circuit Description ..................................................................................................................... 82
3.9.4 Meaning of Connectors, Switches and LEDs............................................................................ 87
3.10 PSU (POWER SUPPLY UNIT) ............................................................................................................... 89
3.10.1 Block Diagram......................................................................................................................... 89
3.10.2 Operation description .............................................................................................................. 90
SECTION 4. TROUBLESHOOTING ..............................................................................................................92
4.1 MBU .................................................................................................................................................... 92
4.2 EMBU................................................................................................................................................ 123
4.3 CHB308 ............................................................................................................................................ 139
4.4 CSB316............................................................................................................................................. 151
4.5 SLIB8 ................................................................................................................................................ 161
4.6 SLU8 ................................................................................................................................................. 167
4.7 VMIU/AAFU ...................................................................................................................................... 173
4.8 VOIB ................................................................................................................................................. 176
4.9 E1HB(RPHB8) .................................................................................................................................. 179

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4.10 CMU12/50PR.................................................................................................................................. 199
4.11 PSU................................................................................................................................................. 200
SECTION 5. PART LIST ..............................................................................................................................202
5.1 BKSU ................................................................................................................................................ 202
5.2 EKSU .................................................................................................................................................211
5.3 CHB308 ............................................................................................................................................ 218
5.4 CSB316............................................................................................................................................. 221
5.5 SLIB8 ................................................................................................................................................ 227
5.6 E1HB................................................................................................................................................. 231
5.7 RPHB8 .............................................................................................................................................. 238
5.8 VOIB ................................................................................................................................................. 245
5.9 VOIU ................................................................................................................................................. 249
5.10 VMIU ............................................................................................................................................... 249
5.11 AAFU............................................................................................................................................... 250
5.12 CMU12PR....................................................................................................................................... 252
5.13 CMU50PR....................................................................................................................................... 253

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SECTION 1. General Description
This manual is intended to provide a full understanding of the architecture, operation, and circuits employed in LG-
NORTEL’s Digital Key Telephone system, ipLDK-60. It is intended for use as an aid in training installation and
maintenance personnel. Also, in conjunction with circuit schematics, this document is intended for use in support of
component level repair by authorized LG-NORTEL repair facilities. The ipLDK-60 is a fully digital switching system
which is intended for small or medium sized business office.
The ipLDK-60 system incorporates state-of-the-art digital technology for command processing and voice switching,
utilizing a Pulse Code Modulation/Time Division Multiplexing (PCM/TDM) distributed switching matrix. The system
supports “A” law voice encoding rule based on the requirements of local regulations.
The ipLDK-60 system achieves a high level flexibility by 1) employing three kinds of option boards, and 2) providing
expansion system.
The KSU of ipLDK-60 is a wall-mounted cabinet that houses the MBU (Main Board Unit) and several connectors for the
CO line/Digital KTU/SLT/Voice mail/LAN interface boards, and other useful boards.
Confidential and Proprietary;
This document contains confidential and proprietary information of LG-NORTEL. It’s use is subject to the conditions that
it should be used only for the intended purposes as stated in this document that it should not be copied or reproduced in
any manner, in whole or in part, without the express written consent of LG-NORTEL.

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1.1 System Connection Diagram
ipLDK-60 system can be connected to several externals and internal line for call processing as following Figure1.1.1
System connection diagram.
Figure 1.1.1 System Connection (ipLDK-60)

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1.2 Special attention of notice
1. Make sure that the power is off and start disassembling the system and board.
2. When dealing with PCB, check the discharge of human body and deal it with the edge of PCB.
3. When changing electric parts (IC, Capacitor or Etc.) and connecting the ring signal, be sure not to touch the lead
wire.
4. When assembling KSU, check the screw.
5. When assembling KSU, check the cable connection.
6. When connecting the external battery, check the polarity of batteries.
7. When assembling KSU, check the connection of protection parts and earth ground.
1.3 System Features
1. Flexible architecture
2. Simplifying system structure
3. Powerful PC application via LAN, Modem, RS-232C
4. Stable & Enhanced voice features
5. Simple installation & efficient system management
- Remote admin & software upgrade through LAN connection
- Remote admin & software upgrade through PSTN modem
6. Value-Added features
- Distinctive voice mail Quality (ADPCM 32 Kbps)
- Basic CID (CO & SLT) Function
- 8 Poly internal MOH (13 Music sources)

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1.4 System Specifications
1.4.1 General specifications
ITEM DESCRIPTION SPECIFICATION
CPU ARM9 TDMI core(32bit, 50MHz)
Switching Device Custom Mixed-Signal ASIC Device
Memory Back-up Duration 10years
AC Voltage Input 100~230 +/- 10% Volt AC @47-63Hz
AC Power consumption 90W
AC Input Fuse 2A @250Volt AC
PSU
DC Output Voltage +5, -5, +27, +30Volt DC
Input Voltage +24 Volt DC(+12VDC x 2ea)
Battery Fuse 5.0A @250Volt AC
Charging Current Max. 200mA
External Backup Battery
Battery Load Current Max. 3A
Ring Signal 75Vrms, 25Hz
External Relay Contact 1A @30Volt DC
Music Source Input 0dBm @600ohm
External Paging Port 0dBm @600ohm
Ring Detect Sensitivity 30Vrms @16-55Hz
Frequency Deviation Less than +/-1.8%
Signal Rise Time 5ms
Tone Duration, on time Min. 50 ms, Normally 100ms
DTMF Dialing
Inter-digit Time Min. 30ms, Normally 100ms
Pulse Rate 10PPSPulse Dialing
Break/Make Ratio 60/40% or 66/33%
Temperature 0 (oC) – 40 (oC)Operating Environment
Humidity 0 - 80% (non-condensing)
KSU 339mm(W) x 288mm(H) x 85mm(D)Dimension
Expansion KSU 339mm(W) x 288mm(H) x 85mm(D)
KSU 1.8KgWeight
Expansion KSU 1.8Kg
Analog Modem Bell, ITU-T, V.34 V.32BIS, V.90
Speed 300bps up to 33Kbps speed rate
MODU
Connection Automatic rate negotiation
LAN Interface 10/100 Base-T Ethernet (IEEE 802.3)
Speed 10/100 Mbps (Auto-Negotiation)
Duplex Half Duplex or Full Duplex (Auto-Negotiation)
VOIP Protocol H.323 Revision 2
Voice Compression G.711/G.726/G729/G.723.1
Voice/Fax Switching T.38
VOIB
Echo cancellation G.165

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1.4.2 Environment Specification
ITEM DEGREES (℃) DEGREES (℉)
Operation Temperature 0~40 32~104
Optimum Operation Temperature 20~26 68~78
Storage Temperature 10~70 32~158
Relative Humidity 0~80% non-condensed
1.4.3 System Capacity
DESCRIPTION CAPACITY/BOARD TOTAL
Time Slots 128
CO Line Ports 3/MBU, 3/EMBU, 3/CHB308,
3/CSB316, 8/VOIB, 30/E1HB8
Max. 36
Max Direct Station (DKT, SLT, DSS)
Connections
8/MBU, 8/EMBU, 8/CHB308,
16/CSB316, 8/VOIB, 8/E1HB8
Max. 48
Max. Door 2/MBU, 2/EMBU 4
LAN MBU, VOIB, E1HB8 3
MODEM Channel 1/MODU 1
Attendant Positions 5/System
Intercom Links Non-Blocking
Paging
- All Call
- Internal
1 zone
5 zones
Station Speed Dial 100/station, 24 digits each 500
System Speed Dial 24 digits each 500
Last Number Redial 15 ~ 50(by admin programming) 32 digits
CO Line Group 8 8
Station Group 10 10
Conference 3~15 Party All ports are available
Multi-Conference 3~15 Party Max. 3 groups
Internal MOH (13 Music Sources) 1/MBU 1
External MOH 1/MBU 1
External Paging port 1/MBU 1
External Relay Contact 2/MBU, 2/EMBU 4
Alarm Input 1/MBU 1
RS-232C Port 1/MBU 1
DTMF/CPT Receiver channels 15 chs/MBU 15 chs
FSK Receiver channels 12 chs/MBU 12 chs
PFT Circuit 1/MBU, 1/EMBU, 1/CHB308,
1/CSB316
4

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1.5 System Configuration
1.5.1 System Configuration
The following Figure 1.2.1 System connection diagram shows the ipLDK-60 system configuration for all kinds of board
in this system that includes the existing boards for the ipLDK-60 system and the developed new boards.
Figure 1.2.1 System Configuration
`
BKSU : Basic Key System Unit
MBU : Main Board Unit
(3CO+1DKT+7Hybrid ports)
PSU : Power Supply Unit (90W)
Basic KSU
VMIU : Voice Mail Interface Unit (4 chs)
Other Option Boards
: 33 Kbps Modem (1 Port)
: 3 CO & 8 Hybrid (8DKTs & 8SLTs)
MODU
CHB308
CSB316
SLIB8
: 3 CO & 16 SLTs
: 8 SLT Port
: 50Hz/12 or 16kHz Call Metering Unit
& Polarity Reversal Detection(3 chs)
CMU50PR/
12PR
Expansion KSU
EKSU : Expansion Key System Unit
EMBU
(3CO+8Hybrid ports)
: Expansion Main Board Unit
PSU : Power Supply Unit (90W)
Terminals
Digital KTU
: LDP -6012D & LDP-6030D
LIP-6212D & LIP-6230D
LDP-DSS, LDP-DPB
SLTs, FAX, Modem, RS-232C, LAN
External Page & External MOH
: Auto Attendant Function Unit (4 chs)
AAFU
E1HB
: E1R2 and 8 Hybrid

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1.5.2 System Components
BASIC KSU
ITEM OPTION BOARD DESCRIPTION
KSU Key Service Unit
PSU Power Supply Unit
MBU Main Board Unit (3CO, 1DKT and 7 Hybrid)
CO and
Extension Boards
CO Line and DKT/SLT interface boards (CHB308, CSB316,
SLIB8, E1HB8 and VOIB)
Main Board
Other Boards VMIU, AAFU, MODU, CMU50PR, CMU12PR can be installed
3CO Lines and 8 Hybrid Interface Board
CMU50PR Call Metering (50Hz) and Polarity Reversal Detection Unit
(3 channels)
CHB308
CMU12PR Call Metering (12KHz or 16KHz) and Polarity Reversal
Detection Unit (3 channels)
3 CO Lines and 16 SLT Interface Board
CMU50PR Call Metering (50Hz) and Polarity Reversal Detection Unit
(3 channels)
CMU12PR Call Metering (12KHz or 16KHz) and Polarity Reversal
Detection Unit (3 channels)
CSB316
SLU8 8 SLT Interface Unit Installed on CSB316 as a default
SLIB8 8 SLT Interface Board
Voice over IP Board (4ch)VOIB
VOIU Voice over IP unit (4ch)
E1R2 and 8 Hybrid Interface Board
CO Line and
Extension
Boards
E1HB8
SLU8 8 SLT Interface Unit Installed on E1HB8 as a default
VMIU Voice Mail Interface Unit, 4 channels
AAFU Auto Attendant Function Unit, 4 channels
MODU MODEM unit (33Kbps)
CMU50PR Call Meeting (50Hz) and Polarity Reversal Detection Unit
(3 channels)
Other Boards
CMU12PR Call Metering (12KHz or 16KHz) and Polarity Reversal
Detection Unit (3 channels)

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EXPANSION KSU
ITEM OPTION BOARD DESCRIPTION
KSU Key Service Unit
PSU Power Supply Unit
EMBU Expansion Main Board Unit (3 CO and 8 Hybrid)
CO and Extension
Boards
CO Line and DKT/SLT interface Boards
(CHB308, CSB316, SLIB8)
Main Board
Other Boards CMU12PR, CMU50PR can be installed
3 CO Lines and 8 Hybrid Interface Board
CMU50PR Call Metering (50Hz) and Polarity Reversal Detection Unit
(3 channels)
CHB308
CMU12PR Call Metering (12KHz or 16KHz) and Polarity Reversal
Detection Unit (3 channels)
3 CO Lines and 16 SLT Interface Board
CMU50PR Call Metering (50 Hz) and Polarity Reversal Detection Unit
(3 channels)
CMU12PR Call Metering (12KHz or 16KHz) and Polarity Reversal
Detection Unit (3 channels)
CSB316
SLU8 8 SLT Interface Unit. Installed on CSB316 as a default.
CO Line and
Extension
Boards
SLIB8 8 SLT Interface Board
CMU50PR Call Metering (50Hz) and Polarity Reversal Detection Unit
(3 channels)
Other Boards
CMU12PR Call Metering (12KHz or 16KHz) and Polarity Reversal
Detection Unit (3 channels)

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Section 2. System Operation Theory
2.1 System Architecture
2.1.1 General Description
ipLDK-60 is a Hybrid Digital Key Telephone System designed to provide digital voice transmission. It uses a digital
switching architecture. A Main Processor (CPU) on the MBU directly controls Option boards and expansion KSU.
The custom main switching device (ACT2) ASIC incorporate a DBID block and two GSL12 blocks for the basic voice
connection of network and extension and features voice switching, conference and voice gain/tone control.
Basically, a PCM highway called MPX bus that is provided by ACT2 and is composed of 32 PCM time slots interfaces
general voice PCM CODECs. Essentially, the DBID block is a Multiplexer/ Demultiplexer providing the ISO layer 1
transport mechanism for the “B” and “D” channels through the system. The Main Processor directs the ACT2 to control
switching on each board.
CODECs are used to convert analog voice signals into Pulse Code Modulated (PCM) digital signals and to decode
digital signals back into analog signals. All routing of voice signals through the system are accomplished in the PCM
digital form.
Control Signals and digitized voice signals for each channel are routed throughout the system on the back plane in a
Time Division multiplexed format (TDM). TDM is a method of utilizing the bandwidth of a transmission line to its fullest
capability by transmitting many channels of information over the same link. There is a unique time interval for the
transmission of each channel. Each channel is sometimes referred to as a “time slot”. These time slots are paired, that
is, there is a transmitting and a receiving time slot for each channel. The transmitting time slot is connected to a
receiving time slot and a receiving time slot is connected to a transmitting time slot to form a full duplex communication
link.
ipLDK-60 has basic KSU and expansion KSU supports wall mounting and rack mounting. It allows any mix of station
boards with CO ports. The system back plane communications channel is distributed to the expansion KSU as a logical
extension of the basic KSU using a 50-pin connector with flat cable. System control is performed by a 32-bit
microprocessor and governed by software stored in (Flash Memory) on MBU. This “Stored Program Control” provides a
very flexible system in terms of features and functions.
2.1.2 Instrument Types
ipLDK-60 Digital Key Telephone System is a digital switching instrument providing digital communications all the way to
desktop.
A. Digital Instruments
The proprietary Digital Key Telephone is a digital voice communication instrument. It means that the voice data
transmitted from and received to these instruments is in digital form. The transmission medium for these instruments is
a single pair of copper wires. Therefore, the full duplex digital voice information, the full duplex digital signaling
information (e.g. lamp status, etc.) and the +30Vdc power for the instrument are carried through the single pair of wires.
The +30Vdc is then regulated to provide lamp voltage and stepped down to ±5Vdc for logic circuits within the digital

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terminal. Digital information is sent to between MBU and Keyset, which employs a Ping-Pong technique which is used
to send voice and signaling information for that instrument. One “B” channel carries digital voice information while the
“D” channel carries signaling information for that instrument to and from digital terminal interface boards.
The GSL12 block of ACT2 on the MBU assembles and disassembles the 2B+D information packets and controls the
digital signal for transmission. Digitized voice is converted to analog voice in the instrument by the Codec device,
coder/decoder and analog voice is converted to digitized voice by the same Codec for transmission back to digital
terminal interface boards.
Signaling information sent on the “D” channel from the digital instrument to digital terminal interface boards is processed
by the micro-processor on MBU. The micro-processor processes requests and sends system status and commands by
digital terminal signaling logic in the GSL12 block to the phone.
Digitized voice information sent on the “B” channel is routed to ACT2 on the MBU for switching and gain control. The
MBU switches the information to a receive “B” channel and informs the receiving terminal on the system such as
another station.
B. Analog Instruments
Analog instruments can be used in ipLDK-60 system. Analog voice communication is sent over the single pair of wires
from the single line interface boards to the station.
CODEC on the SLT interface circuits is used to convert digital voice signals to analog voice signals before being sent to
the analog instrument and to converts analog voice from the phone to digital PCM signals before routing them through
the system.
2.1.3 Capacity Limitations
A. CO Ports
It allows max. 12 central office lines to be connected to the system.
B. Station Ports
The maximum number of station (Digital KTUs or SLTs) installed on the system is 48 (Max 32DKTs, 47SLTs).

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2.2 Switching
2.2.1 Back plane Architecture
ipLDK-60 system has PCM highway called MPX bus to interface voice CODECs on the MBU and Option boards to main
switching device ACT2.
For extension boards and expansion KSU on which additional PCM highway is needed, system back plane architecture
called ISC highway provides interfacing custom blocks such as DBID and GSL12 in ACT2 on the MBU.
The ACT2 has the DBID block and the two GSL12 blocks that provide a MPX bus and 15 pairs of ISC highways. A MPX
bus is composed of 36 PCM time slots that are assigned to basic voice CODECs on the MBU and voice CODECs on
the CO ports.
Expansion MBU also has custom back plane interface blocks such as DBID and GSL12 to transmit and receive “B” and
“D” channels information for stations and circuits
A. EXP_ISC Highways
EXP_Inter-System Communication (EXP_ISC) Highways are buses on the back plane that distribute digitized voice and
signaling data, and carry out board level communication throughout the system connector(s). These highways are
provided in transmitting/receiving pairs and there are a total of 3 highway pairs in ACT2. Communication on each
highway is at 8.192Mbits per second in a time division multiplexed format. Time division multiplexing creates “channels”,
or time slots, that carries digitized voice, signaling data, and High-Level Data Link Control (HDLC) protocol information.
Voice (“B”) channels carry digitized voice signals. Signaling (“D”) channels are employed for channel specific signaling
implementation.
B. Channel Allocation
The Main Board Unit (MBU) determines which time slot on which ISC highway will be used to transmit and receive “B”
and “D” channels information for all stations and circuits. The DBID or GSL12 block in ACT2 the “B” and “D” data onto
the system highway at the appropriate time slot. Any port can be assigned to transmit on any transmit “B” channel and
receive on any receive “B” channel. The “D” channels can also be flexibly assigned and controlled independently of the
“B” channels. The HDLC inter-board communication channel on each highway is also controlled by the main processor
on the MBU and placed on the highway by the DBID on peripheral board.
C. Voice Channels
PCM signals received from the digital instrument are placed on a back plane highway transmit “B” channel and sent to
the MBU where gain modification and/or conference summations take place. The output is placed on a back plane
highway receive “B” channel for the receiving port. All voice channels are fully 64Kbps digital time slots.
2.2.2 Signaling Channels
The “D” channels are 16Kbps channels designed to carry channel specific signaling information and low-speed user
data.

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2.3 Administration
2.3.1 General Description
ipLDK-60 Hybrid Key Telephone System utilizes stored program control technology. It means that system time slot
switching, hardware control, and all feature implementations are controlled by software code residing on memory in the
system. There are 3 types of memories used by the system, System Generic memory, Scratched memory, and
Customer Database memory. All 3 types of memories are contained on the Main Board Unit (MBU).
2.3.2 System Generic Memory
The first type of memory is called System Generic memory and is stored on Flash memories on MBU. This memory is
used by the Main Processor and dictated how the system operates, controls all feature implementations, monitors all
functions, etc. The System Generic memory cannot be changed, however upgraded software can be downloaded to
add new features to the system or change feature operation.
2.3.3 Operating Memory
The second type of memory is a system operating memory. This type of memory is a SDRAM (Synchronous Dynamic
Random Access Memory) and is used for system operating). The memory is lost when system power failure is occurred
and it is always initialized on system power-up.
2.3.4 Customer Database Memory
The third type of memory is called Customer Database memory. This memory is stored in RAM (Random Access
Memory) and is used to store the data and status of programmable features (e.g. line ring assignment). Customer
database memory is maintained during power failure by an onboard lithium battery. It is the customer database
memory that must be initialized upon the first installing the system so that a known “default” database can be used to
start building a customized customer database.
2.3.5 System Resources
System resources are functions made available for users on the system to support features and optional functions on
the system.
A. Tone Generation
The system generates tones which are available on the system back plane “B” channels. These tones are stored
digitally in ACT2. For instance, when a station is received intercom dial tone, it is commanded to monitor the “B” voice
channel where system intercom dial tone resides. This procedure is the same for all tones including ringing tones, busy,
recorder and ring-back tones.
B. DTMF Tones
1) DTMF Receivers
The system provides the ability to monitor and identify a Dual Tone Multiple Frequency (DTMF) tones generated
externally. It supports system features and functions such as Single Line Telephone DTMF dialing and DISA calls. Calls

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requiring DTMF monitoring are connected via a system “B” channel to one of 15 DTMF receiver channels in ACT2. And
the CPU on the MBU identifies which digit is generated from Single Line Telephone (SLT).
2) DTMF Tone Generation
With call processing tones, the system generates DTMF tones from digitally stored tones in ACT2 as a Look-up table.
DTMF tones in digital PCM form are injected onto the receive highway at the proper time slots by a digital summation
technique and digital gain modified by the Tone Generation block in ACT2 device on the MBU board. More about the
digital summation and gain process are discussed in section 2.4.3. Conferencing.
C. Real Time Clock
The system maintains its own real time with a real time clock circuit. The day, date and time are stored in the Device
retained in the system by the on-board lithium battery on the MBU. The clock is used for many system features such as
LCD time & date display, SMDR time & date printout, the wake-up call feature, etc.
D. System Information input/output (I/O)
The system can communicate detailed call records, customer database changes and diagnostic routines through multi-
purpose hardware I/O ports on the system MBU. A channel Universal Asynchronous Receive /Transmit (UART) device
is used to provide access to system terminal programming and diagnostic routines. The UART is directly connected to
I/O port of the MBU microprocessor. With the UART, terminal programming and system SMDR printout can be
accomplished simultaneously. The system customer database programming routines are directed by the system generic
software allowing only one communication port to access customer database programming at a time.
1) RS-232C Communication
ipLDK-60 system provides a port of serial communication standard, RS-232C that is implemented by the first UART of
CPU. It provides asynchronous serial communications up to 19200 baud rates. A log-on procedure is used to enter the
system terminal programming mode and ASCII characters and control codes are used to modify the customer database.
The 9 pin RS-232C port is configured as Data Communication Equipment (DCE). Data is transmitted on pin 2 and
received on pin 3. Hardware flow control is supported with a Clear To Send function on pin 7. The system will halt
transmission of data when this signal is asserted by the connected equipment.
2) Modem Communication
The optionally equipped modem unit functions on the second UART of main CPU (S3C4530A). Interface connectors on
the MBU allow the Modem unit to be installed as an option on the MBU. The modem will answer incoming line ringing to
the specified CO line with modem carrier tone. Modem communications will support up to 33k baud rates.
E. Digital Voice Announcement
The system optionally provides digitized voice announcements for system and station features. When the Voice Mail
Interface Unit (VMIU) is installed on MBU, features supported to the VMIU are provided with pre-recorded system voice
announcements, customized hunt group announcements and customized user voice announcements. The VMIU
provides 4 channels of access to voice announcements. All kinds of voice messages are stored digitally on NAND flash
memory and related information for voice are stored on RAM that is retained during power failure with a lithium battery
on MBU. When commanded by the MBU, the appropriate digitized voice announcement is converted from compressed
digital format to a PCM digital signal and placed on a receive “B” channel. The requesting station or system port is then
commanded to monitor that channel. System software control terminates the voice announcement and frees-up the
channel on the VMIU when the announcement is completed. When storing a customized voice announcement, the

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requesting station is assigned a transmit “B” channel and the VMIU is assigned a corresponding receive “B” channel.
The VMIU connects one of its 4 ports to the receive channel and starts monitoring for sound. If no sound is detected, the
recording is stopped and the connection is broken down. If sound is detected, the digitized PCM voice is converted into
compressed digitized audio and stored on NAND flash memory. The length of recorded announcements is monitored
and recording is stopped if the maximum announcement length for the message being recorded is exceeded.
2.4 Call Processing
2.4.1 Internal Call Types
A. Intercom
Intercom calls begin with a station going off-hook. The station or station board receives the off-hook data and
communicates to the MBU. In response, the MBU places digitized intercom dial tone on a “B” channel. The station or
station board in turn switches this “B” channel to the requesting station which converts the digital signal to analog audio
and the station hears the dial tone.
When you dial digits or press button on the phone, the same communication exchange from station or station board to
MBU and back take place. It informs the MBU of the request, such as dialing an intercom number. The MBU then
checks the scratch pad memory for status of the dialed phone and a connection is established by assigning transmitting
and receiving “B” channel pair for both stations. Or a call progress tone is sent to the initiating phone such as busy tone.
B. Paging
Paging is a programmable feature either enabled or disabled in customer database programming. When a station
places a page request, the MBU must check scratch pad memory at first to determine if the page zone is busy. Then the
customer database programming must be checked to determine if the station is allowed to initiate a page, and to
determine which stations are to receive the page. Stations that are not busy when the page was activated will be placed
in the off-hook mode and will monitor the receive “B” channel assigned to that station.
External pages are set up in the same way however, communication to an external page zone can be 2-way, meaning a
talkback speaker can be used for the external zone and the speaker can transmit voice back to the page initiator.
2.4.2 Outside Call Types
A. CO Calls
CO calls connect a station in the system to a central office port (telephone line) on the system. It provides access to the
Public Switched Telephone Network (PSTN). When an outside line is requested by a station, the CO line interface is
terminated providing CO dial tone from the local central office. A transmitting and receiving “B” channel pairs are used
on the system ISC highway to route the PCM digitized audio between the station and the CO line circuit.
When the station dials DTMF digits, the dialed digit data is communicated to the MBU which in turn injects PCM data of
the dialed digit DTMF tones onto the transmitting “B” channel through digital summation techniques. The CODEC
associated with the CO Line decodes the PCM data into the analog wave form which is placed on the CO circuit and
sent to the local central office to establish the call connection. After the call is established, the system monitors the CO
line for open loop disconnecting supervision. If the tip and ring loop is open during the programmed loop supervision
time, the system disconnects the call.

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2.4.3 Conferencing
Conferencing is accomplished on the ipLDK-60 system by using switching block of a special custom integrated circuit
called the ACT2. This device uses a technique that involves the real time digital summation of two ports (conferee’s)
PCM data. That is, the digitized voice is added together in a digital format, and then placed on the appropriate “B”
channel. For a 3-party conference (ports A, B & C), port A will require that ports B & C be summed and placed on the
receive time slot for port A. Port B will require that ports A and C be summed and placed on the receive time slot for port
B. Port C will require that ports A and B be summed and placed on the receive time slot for port C. This provides a
feature of 3-party conference on the system.
Since the system is designed to provide up to 3 parties in a conference, the switching block on the ACT2 was
incorporated to provide this function. The digital summation process can store its output into this function. The digital
summation process can store its output into this conference memory of switching block. The memory is large enough to
support many digitally stored summations. The summed conference memories can then be used as one or both inputs
for additional summations and its output stored in memory again or placed on a “B” channel. Conference memory is
large enough to allow unlimited 3-party conference at the same time. Gain modification is performed by the switching
block. A look up table stored in ACT2 permits PCM words to be adjusted for the circuits receive volume level. The gain
word (volume level) is used as the Gain ROM index with the PCM word as the address. The output from the Look-Up
Table is the gain modified PCM signal which is placed on the appropriate receive “B” channel.

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SECTION 3. Circuit Description
3.1 Main Board Unit with CO
3.1.1 General
The MBU is the Main Board Unit of IPLDK-60. It provides basic CO, Station and extension interface circuits, physical
connection with various boards, and also miscellaneous functions.
The MBU is composed of a main processor and its peripheral circuits, the three CO interface circuits, a Digital Keyset
Unit (DKT) interface circuit, 7 hybrid circuits that are selected to DKT or SLT ports by Modular Jack pin assignments, a
Ring Generator circuit, a system battery backup circuit, two general purpose relay contact, an internal MOH, an external
MOH, an external PAGE, an alarm sense and the master clock generation circuit, as well as system’s PCM voice
processing circuit that has custom switching device, ACT2, for PCM tone generation and PCM Gain control .
And it also has various connectors to install CO, extension and function boards, switches, modular jacks and etc.
Basically, the MBU provides the capacity of 3/08, that is three CO interface circuits and eight extension terminal
interface circuits that are composed of 1 DKT port and 7 Hybrid ports.
The capacity of IPLDK-60 system can be extended to maximum 12/48 that means the twelve CO interface ports and the
forty-eight extension ports by adding EKSU, CHB308 and CSB316 board.
The system features can be added by installing function boards at connectors that are prepared on the MBU.