EX7100 Training Course - Master Version 1_0

EX7100 Training CourseEX7100 Training CourseVersion 1.0, October 2005

Page 2 Last Mile Wireless Communication SolutionsLast Mile Wireless Communication Solutions

Course objectivesCourse objectives

Upon completion, participants will be able to: Install and commission a EX7100 link

Set-up and configure the system to be compatible with different network configurations

Alignment of system and modules

Fault find to module level


AgendaAgenda

Day 1 Introduction

Module 1. EX7100 overview

Module 2. Module description and specifications

Module 3. Getting started - System software & management

Day 2 Module 4. Networking & Digital RF systems

Module 5. Voice networks

Module 6. Data networks

Module 7. RF network


Agenda Cont’dAgenda Cont’d

Day 3 Module 8. Installation and commissioning Module 9. Site and system planning Module 10. Site considerations

Day 4 Module 11. Electro static discharge (ESD) Module 12. Diagnostics, maintenance and fault finding Module 13. System alignment

Day 5 Module 14. Repeater systems Module 15. Practical activity


AnnexAnnex

EX7100 system training manual

EX7100 handouts


History of EXICOMHistory of EXICOM

1913 1988

1992Circa 1970

June 1996

2003

NEW ZEALAND


EXICOM todayEXICOM today


EXICOM today Cont’dEXICOM today Cont’d

EX7100 OverviewEX7100 OverviewModule 1.


IntroductionIntroduction

The Exicom EX7100 is a 64kbps digital radio system providing either six telephone circuits or 1 single 64kbps data channel in various interface configurations. In telephone mode the EX7100 effectively acts like a pair of copper wires, in that it passes most signalling between the customer’s telephone and the exchange. The EX7100 replaces these copper pairs with reliable, full CCITT standard radiotelephone connection, using DSP and Voice encoding technology supporting payphone, fax, modem data and some point of sale terminals.

The single 64kbps channel option can provide various interface including ITU-T compliant G.703 and synchronous V.35. This allows convenient connections to external OEM multiplexers, bridges, and router at data rates of 64kbps.


Conceptual ViewConceptual View


Key benefitsKey benefits

Six Telephone Circuit or 64kbps data interface over 25 kHz digital radio

Spectrally efficient, allowing 64kbps into one 25 kHz

Interfaces to Telephone, Fax, Modem, Payphone, and Point of Sale

Terminals

Reliable operation under difficult physical environmental conditions

Ideal for use in public and private telephone, digital or radio networks

Extensive local and remote diagnostics

Exceeds G.821 error performance for international digital circuits


Product featuresProduct features

Digital G.703 (E0) and Synchronous data interface

Transparent 64kbps data available to the user

Optional integrated multiplexer providing six low bit rate

voice/fax/modem circuits

Automatic fax and modem data detection for most protocols

“On-Demand” transmit option for reduced power consumption


Product features Cont’dProduct features Cont’d

Inherent security through digital encoding

Repeater option available

Very high system gain with 2 or 10 Watt transmitters

Self contained, solid aluminium 19” rack mounted chassis

Integrated micro-controlled fans provide active cooling as the radio requires


EX7100 applications 1EX7100 applications 1

ENTER

POWER

ALARM

Rx LOCK

Tx ON

EEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEE EETP1

GND

EX7100Digital Radio

ENTER

POWER

ALARM

Rx LOCK

Tx ON


GND

EX7100Digital Radio

EX7100EX7100

PSTN

PABX or CO Switch

6

EX7100 Six Telephone circuit application:Transport of standard 2-wire telephony

circuits using the EX7100.

Telephone

Telephone

Telephone

Telephone

Telephone

Telephone



ENTER

POWER

ALARM

Rx LOCK

Tx ON


GND

EX7100Digital Radio

ENTER

POWER

ALARM

Rx LOCK

Tx ON


GND

EX7100Digital Radio

EX7100EX7100

PSTN PSTN

PABX or CO Switch

PABX or CO Switch

6 6

EX7100 Six circuit application:Transport of PABX or CO switch Truck lines. EX7100 configured for 4-wire E&M operation.



ENTER

POWER

ALARM

Rx LOCK

Tx ON


GND

EX7100Digital Radio

ENTER

POWER

ALARM

Rx LOCK

Tx ON


GND

EX7100Digital Radio

EX7100EX7100

PSTN

PABX or CO Switch

6

EX7100 Six mixed telephony and data circuits:

Transport of standard 2-wire telephony circuits using the EX7100 for POTs or data

services.

Telephone

Telephone

Modem

Modem

Fax

Point Of Sale



ENTER

POWER

ALARM

Rx LOCK

Tx ON


GND

EX7100Digital Radio

ENTER

POWER

ALARM

Rx LOCK

Tx ON


GND

EX7100Digital Radio

EX7100 EX7100

EX7100 64kbp/s data mode application: Transport of 64kbp/s of digital data over

EX7100.

Multiplexer Multiplexer

Module description and specificationsModule description and specificationsModule 2.


System block diagramSystem block diagram

Modem Framer

Transmitter

Receiver

PowerAmplifier

PowerSupply

Front Panel Display

RS-485 Bus

G.703 / Sync Data

6-ChannelLine Mux

68 kbit/s

Control

I

I

Q

Q

AGC/AFC

64 kbit/s

64 kbit/s

6 Ch

Management Port

Control Port

6 Channel FXO or FXS

Port

G.703 / SyncData Port

Duplexer

+24V+15V-15V+5V-5V

10 - 30Vdc or30 - 70Vdc


System interconnectSystem interconnect


System HardwareSystem Hardware

The hardware consists of the following modules:

General Non RF Modules Power Supply Module Type 2964

Modem/Controller Module Type 2966

Front Panel Type 2994


System Hardware Cont’dSystem Hardware Cont’d

RF Modules

VHF/UHF Transmitter Module Type 8027/8053

UHF CPU Module Type 8053

VHF/UHF Receiver Module Type 8029/8054

VHF/UHF Power Amplifier Module Type 8028/8048

VHF/UHF Front End Module Type 8018/8055

VHF/UHF Duplexer Filters Type 8013/8045


System Hardware Cont’dSystem Hardware Cont’d

Line Interface Module (Only present in six channel variant)

2-wire 6 channel exchange line interface module Type 2967

4-wire module Type 2967 (Optional sub-module of the exchange

line module)

2-wire 6 channel subscriber line interface module Type 2971

Isolated power supply Type 2990


Specifications – SystemSpecifications – System

System 16 QAM modulation

3 VHF Bands: 138 – 174 MHz

5 UHF Bands: 403 – 512MHz

64kbit/s available bandwidth (68kbit/s including overheads)

25kHz Channel Bandwidth

Duplex spacing• VHF: 4.6 – 10 MHz

• UHF: 5 – 13 MHz

Frequency Selection 5 or 6.25 kHz

50 N type female connector at antenna port


Specifications – TransmitterSpecifications – Transmitter

Transmitter Adjustable Tx RF Output: +31-40dBm (1.25-10W) adjustable in

3dBm steps

2W version available

100% duty cycle at 60C (140F) ambient, <3000m AMSL

Emission designator: 18K4D1WET


Specifications – ReceiverSpecifications – Receiver

Receiver Receiver sensitivity:

• Normal Temperature– 10-3BER <-105dBm (<1.3V) @ Rx input– 10-6BER <-102dBm (<1.8V) @ Rx input

• Extreme Temperature– 10-3BER <-102dBm (<1.8V) @ Rx input– 10-6BER <-98dBm (<2.8V) @ Rx input


Specifications – Data ChannelSpecifications – Data Channel

Data channels CCITT G.703 or Synchronous Data interfaces

64kbps full data rate

Connections:• Unbalanced G.703 - 75 BNC

• Balanced G.703 - 120 DB15

• Synchronous Data - DB15


Specifications – Voice ChannelsSpecifications – Voice Channels

Voice channels Six low bit rate voice/fax/data channels.

Automatic fax and data detection and regeneration (V.22, V.22bis, V.23, V.27ter, V.29, V.32 and G3 up to 9.6kbps)

6.4kbp/s MP-MLQ Voice compression (ITU-T G.723.1)

Adjustable Send/Receive Line Levels –15 to +3dBm

600, 900 and complex 2 wire line impedance (4 wire 600).

25 or 45mA selectable line drive current.

12/16 kHz payphone meter pulse and line reversal.


Specifications – PSUSpecifications – PSU

Power supply options Low (10.8 – 30Vdc) or High voltage (30 – 70Vdc) DC/DC

converter (integral)

110/230 Vac external power supplies available

Getting started – system softwareGetting started – system softwareModule 3.


EX7100 front panelEX7100 front panel


User interfaceUser interface

The user interface consists of: 4 navigation keys

1 Enter key

1 Escape key

16 x 2 LCD screen

2 Test points

4 Status LEDs


PC interfacePC interface

Using the optional ELMS (Exicom link management system) software the user can:

Monitor and interrogate the link

Check the status of the terminal (remote & local)

Change parameters (remote & local)

A PC can be connected either via a serial cable or remotely using a modem.


User interface keysUser interface keys

4 navigation key allow the user to scroll through menus and change parameters e.g. passwords. The ‘Escape’ key enables the user to back out of the menu location.

Pressing the ‘Enter’ key will accept the current selected parameter or allow access to the next menu screen.

The → shows the position of the cursor.


Password accessPassword access

The user interface has a two level password access.

1. Low level password for gaining access to the user menu. Default ‘1111’ (can not be changed)

2. High level password to allow changes to the key operating parameters. Default ‘1234’ (can be changed)

Password ****


RS232Remot e Test s

Menu structureMenu structure

Depending on the type of terminal the menu structure has 8 to 9 sub menus.

Exi com EX71001 J AN 1200: 01

Cont rol l erRF Par amet er sRF Par amet ers

Fr amerFramerPSU Moni t or i ngPSU Moni t or i ng

ExchangeExchangeRS232

Subscr i berRS232Remot e Test s

Al ar msAl ar ms

OR Option


Universal parameters Universal parameters

The EX7100 include a number of universal parameters. Some examples of these are:

Passwords

Time / Date

Operating mode

Link ID


System time / dateSystem time / date

The time and date should be changed to reflect the local setting. The date time fields follow the UK format: DD/MM/YY.

To change the time / date, the cursor must be positioned over the required digit using the ‘left / right’ keys and changed using the ‘up / down’ keys.

Set Ti me/ Dat ePassword 1201: 01 01/ 01/ 03

Cont r ol l erRF Par amet er s


System operating modeSystem operating mode

The EX7100 is capable of two operating mode:

Terminal 100% - Link continually active (Tx & Rx active constantly).

Terminal on Demand – Link active only when traffic is present.

Operat i on ModeSet Ti me/ Dat e

Ter mi nal 100%*Ter m on Demand Repeat er 100% Rpt r on Demand

Cont rol l erRF Paramet ers


Link IDLink ID

The link ID stops the EX7100 from setting up a link when an interfering RF signal is present.

Li nk I DTer mi nal Desc

Li nk I D: 01 Change Li nk I D

Cont r ol l erRF Par amet er s


Terminal descriptorTerminal descriptor

A 16 character descriptor can be set to display when the user menu is idle or instead of the ESN when being accessed from a remote location.

Termi nal DescESN

Cont rol l erRF Par amet ers

Exi com EX7100 Change

Exi com EX71001 J AN 1200: 01


Critical parametersCritical parameters

Critical parameters are any parameters that by incorrectly changing can cause the loss of link or contact with the remote terminal. The settings listed are considered critical parameters:

Channel Increments (5 or 6.35kHz)

Tx Operating Frequency

Rx Operating Frequency

Tx Power

Interface type


Changing critical parameterChanging critical parameter

The critical parameter will not change until a ‘Test New Config’ routine is preformed.

‘Test New Config’ procedure is only required when critical parameter are changed remotely.

If any critical parameter on either remote or local terminals is incorrect no changes will take place.


Test new configurationTest new configuration

After the changes have been made to both terminals the configuration must be validated or tested.

Remot e Test sAl ar ms

Test New Confi g

New Confi g OKUsi ng New Confi g

New Confi g Fai lUsi ng Ol d Confi g

Pl ease Wai tTest i ng Confi g

Networking & Digital RF systemsNetworking & Digital RF systemsModule 4.


Network InterfacesNetwork Interfaces

The EX7100 is available in two variants…

Six channel Voice/Fax/Modem Data interface or…

64 kbps Digital Data interface.


Demands on Analogue Radio SystemsDemands on Analogue Radio Systems

More demand’s have been placed on greater information capacity, higher signal quality, improved security and digital data compatibility. Analogue AM and FM modulation techniques, while valuable, have proven inadequate to match today’s needs for high-volume traffic. With millions of cell phone subscribers gobbling up voice bandwidth, we need a modulation method that can transfer information more efficiently and reliably.


Digital ModulationDigital Modulation

There are numerous digital modulation schemes in use in today’s modern equipment but one technique that lends itself well to digital processes is called “IQ Modulation”. The IQ Modulation scheme the EX7100 employs is called 16-QAM (Quadrature Amplitude Modulation)


Why Go Digital?Why Go Digital?

Can handle both data and voice

More efficient

Once the Baseband signal (voice or data) is digitised, we can effectively do whatever we want with it. This means digital algorithm’s can be created that requires fewer bits to be transmitted. Fewer bits, means more users or higher data rates can be accommodated


QAMQAM

As with most modulation schemes, when a carrier is modulated with the Baseband signal, the carrier’s waveform is changed slightly. In the QAM modulation schemes, the amplitude (Amplitude Modulation) as well as the phase (Quadrature) of carrier is modified.


I/Q PlaneI/Q Plane

We can treat the modulating signal as a phasor where the real axis is “in-phase” (I) and the imaginary axis is the “Quadrature” (Q) component.

The ‘I’ and ‘Q’ Baseband signals are manipulated to product the modulated carrier.

Both ‘I’ and ‘Q’ inputs are dc voltage values.

Each ‘I’ and ‘Q’ coordinate represents a binary bit.


I/Q Plane ExplainedI/Q Plane Explained

For example;

I = Binary 0 with o/p = +1Vdc and

Q = binary 0 with o/p = +1Vdc

Then the output Amplitude = 0.707Vdc with a Phase angle of 45 (see figure B).

I = M*cos

Q = M*sin

M: Magnitude, : Phase angle

Figure A.Un-modulated@ Unity Gain

Figure B.Modulated

Assuming unity Gain (Magnitude of 1)

at 45. ‘I’ and ‘Q’ will therefore have an amplitude of 0.707Vdc

Q Q

I I


16 QAM16 QAM

The previous screen showed an example of single coordinate or phase state. But this example uses a 2 binary bit (commonly called symbols), which will permit four phase states. These four states represent the bit rate, thus the maximum theoretical bit rate for a 4-QAM system is 8kbit/s


16 QAM Cont’d16 QAM Cont’d

Now consider a symbol rate of four bits.

The ‘I’ coordinates can be either a positive or negative values and can have two amplitude levels. (2 Bits)

The ‘Q’ coordinates can be either a positive or negative values and can have two amplitude levels. (2 Bits)


16 QAM Cont’d16 QAM Cont’d

A symbol rate of four bit represents 16 phase states (16-QAM) which gives a maximum theoretical bit rate of 64kbit/s.

Figure 1. 16 QAM constellation. Figure 2. 16 QAM circuitry.


IQ Mapping tableIQ Mapping table

Binary Input 16 QAM Output

Q Q’ I I’ Magnitude Phase Angle

0 0 0 0 1.414 +45.00

0 0 0 1 3.162 +18.43

0 0 1 0 1.414 +135.00

0 0 1 1 3.162 +161.56

0 1 0 0 3.162 +71.56

0 1 0 1 4.242 +45.00

0 1 1 0 3.162 +108.43

0 1 1 1 4.242 +135.00

1 0 0 0 1.414 -45.00

1 0 0 1 3.162 -18.43

1 0 1 0 1.414 -135.00

1 0 1 1 3.162 -161.56

1 1 0 0 3.162 -71.56

1 1 0 1 4.242 -45.00

1 1 1 0 3.162 -108.43

1 1 1 1 4.242 -135.00


I

0001 0100 1111 0111 0110 1000 1101 1100 1011 1110 1010 0000 0101 1001 0010 0011

Demodulated 16 QAM ConstellationDemodulated 16 QAM Constellation

Vector Plot

Simulation

Binary Output

Q

Voice networksVoice networksModule 5.


Six Channel Line ModulesSix Channel Line Modules

The EX7100 was designed to deliver up to 6 low bit rate voice, fax or modem data channels over an efficient 25 kHz radio channel. To achieve this, the EX7100 uses CODEC compression techniques in the 6 channel line module. In particular, the MP-MLQ (G.723.1) scheme is used. This provides 6 voice channels at 10:1 compression (6.3 kbps) with a MOS rating of 3.9.

The module also allows the use of modem or fax data of up to 9.6 kbps. Unlike analogue radio the modem and fax tones are not passed through the radio in-band but are instead ‘relayed’ across the link in the digital stream. Each end must effectively act as a modem, detect the tones and then switch to the correct protocol.

Secondary protection to the EX7100 is provided by thermistors, dual transient voltage protectors and Zener diodes (low level).


Telephony interface settingsTelephony interface settings

Two interface options are available (depending on the terminal) for telephony mode:

Exchange – Used when the terminal has an ‘Exchange line card’ fitted.

Subscriber – Used when the terminal has a ‘Subscriber line card’ fitted.

Fr amerPSU Moni t or i ng

I nt er f aceDat a Cl ock

G703 Codi r G703 Cont r a Sync Dat a Subscr i ber Exchange


Telephony operating modesTelephony operating modes

The operating modes for telephony can be set for either:

Point to Point – Used for 6-wire trunking (only available when systems have 4-wire E&M modules fitted).

Exch – Subs – Normal 2-wire telephony mode.

ExchangeRS232

Oper at i ng ModeChannel Set up Poi nt t o Poi nt

*Exch t o Sub*


Six channel InterfaceSix channel Interface

The EX7100 telephony ready option comes complete with a low bit rate six channel voice multiplexer. This allows full use of 6 voice or modem / fax data channels over a standard 25 kHz channel radio.

6 low bit rate Voice/Fax/Modem channels (optional Async V24/RS232)

Modem/Fax/Data bit rate up to 9600 bps (V.32 modem, G3 Fax)

2-wire or optional 4-wire telephony interfaces.

Selectable audio levels, line impedance, and telephone line current.

Inbuilt payphone metering detection and generation.

Support for CLID, Tone & Pulse Dialling


Six channel Interface Cont’dSix channel Interface Cont’d

Unlike analogue radio systems, the voice, modem/data, fax, and payphone metering must be detected and recreated (relayed).

Fax relay supported: CCITT V21, V.27ter, and V.29

Modem relay supported: CCITT V.21, V.22bis, V.23, V.32, and Bell-212A Full Duplex


Voice Coding/Decoding (CODEC)Voice Coding/Decoding (CODEC)

For normal telephony, the audio frequency must first be detected in the EX7100 and then converter to a digital signal using an Analogue to Digital Converter. The signal is then compressed using proprietary voice encoding schemes.

10:1 compression permits six voice channels to fit within a single 64 kbps channel.

MP-MLQ (Multi Pulse – Maximum Likelihood Quantization) technique is used for voice compression.

Voice quality - MOS 3.9 Near Toll Quality

Inherent voice/modem data security due to proprietary voice coding and multiplexing techniques.


Mean Opinion Score (MOS)Mean Opinion Score (MOS)

The quality of the sent speech through a CODEC is at the discretion of the listener. One benchmark used to determine the quality of the audio produced by a specific CODEC is the mean opinion score (MOS). The MOS rating is judged by a wide panel of listeners to give scores on a scale of 1 (bad) to 5 (excellent). The scores are then averaged to provide the MOS rating for that CODEC.

Figure 1. Typical MOS rating set-up. Note MOS rating of 4 = toll quality.


Echo CancellingEcho Cancelling

Telephone echo can occur at a number of areas in the circuit. There is near end echo which occurs when the local telephone and line is not matched correctly and far end echo which occurs when the remote telephone is not matched to the line.

To minimise the effect, the EX7100 employs echo cancellers. The cancellers conform to ITU G.165 recommendation and operate over a 16 ms period. A minimum of 6 dB echo loss is required for correct canceller operation.


Telephone line signalsTelephone line signals

Various signalling mechanisms are used on the telephone line and the EX7100 handles these in much the same way as the modem/fax data by detecting and regenerating at the far end.

Some examples are:

• On hook – Off hook

• Hook flash

• 12 and 16 kHz metering pulses

• Line reversal

• Decadic dialling

• Ringing (Standard and distinctive ring)

• Calling Line ID

1 Verified fax and modem protocols are listed in the EX7100 specifications


Changing audio line levelsChanging audio line levels

Both receive and transmit audio levels are selectable in 0.5dBm step from -15dBm and +3dBm.

Note: Each channel can be selected individually.

ExchangeRS232

Tx LevelRx Level

Rx LevelLoopback

Al l *0. 0dBm

Al l * - 3. 0dBm

+3dBm

- 15dBm

Subscr i berRS232

OR


Changing line impedanceChanging line impedance

Three selectable line termination impedances are available, 600Ω, 900Ω or complex.

Channel Set upMet er i ng

ExchangeRS232

Subscr i berRS232

OR

900Comp4W


Changing the loop currentChanging the loop current

If additional telephones are connected or excessively long distances are experienced between terminal and telephone, the loop current may need to be increased to compensate.

Subscr i berRS232

Loop Cur r entLoopback

Al l *25mA

45mA


4 Wire + E & M operation4 Wire + E & M operation

An optional 4 wire + E & M module may be fitted at each end of the link. This allows the EX7100 to be used to extend or ‘trunk’ a telephone exchange. If used in trunking mode, the M wire is used to trigger the establishment of the link by grounding. This will correspond to a grounding of the E wire at the far end which in turn will open the audio.

-ve M-Wire (type I):

Activation achieved by pulling from a +ve Voltage to -ve Voltage.

+ve M-Wire (type V):

Activation achieved by pulling from a -ve Voltage to +ve Voltage.


Setting 4-wire operationSetting 4-wire operation

If the optional 4-wire module is fitted the exchange terminal can be for set ‘point to point’ or ‘2-wire / 4-wire’ mode.

ExchangeRS232

ExchangeRS232

Oper at i ng ModeChannel Set up

Poi nt t o Poi nt*Exch t o Sub*

Channel Set upMet er i ng

Al l *4W *600


2 Wire to 4 wire operation2 Wire to 4 wire operation

The EX7100 can operate with a 4 wire exchange to 2 wire subscriber link. When the M wire at the exchange is grounded, line ringing is applied to the subscriber end. When the customer picks up the receiver, the ringing is tripped thus looping the line. The E wire at the exchange end is then grounded and the audio path is opened

Data networksData networksModule 6.


Interface availableInterface available

The following choices are available for the 64 kbps data interface. ITU-T G.703

• 75 Unbalanced (Tx & Rx 75 BNC Connection)

• 120 Balanced (DB15 Connection)

Synchronous Data • V.35

• Other interfaced available based on V.10/V.11 electrical circuit recommendation.

External Ethernet 10BaseT – Option• Network Segmentation: Bridge (layer 2) or Router (Layer 3)

• Interface requires external power source.


64 kbps Data Interface64 kbps Data Interface

The EX7100 data interface allows the consumer full use of 64 kbps of digital data using various data interface standards.

Allows customers choice of various interfaces.

EX7100 appears semi-transparent to external data interfaces.

Customers need not re-configure external equipment.

DCE to DTE semi-transparency

(Synchronous interfaces require the use of specific cables available from EXICOM).

Note: When the six channel version is configured for 64 kbps data, all six voice channels are disabled.


G.703 (DS-0) interfaceG.703 (DS-0) interface

The G.703 interface allow the user a choice of either:

G.703 co-directional or

G.703 contra-directional.

In addition the co-directional interface connection can be either:

75 Unbalanced (Tx & Rx 75 BNC Connection)

120 Balanced (DB15 Connection)


Sync data overviewSync data overview

The EX7100 is designed to provide either 6 channel telephony/modem data or 64 kbps Data communications. In particular, the sync data port allows the user to transport full 64 kbps of data using ITU compliant interface.

The sync data port provides flexible interface options. Types of interface available are V.35, V.36/V.11 (RS449/422) or V.24 (RS232).


Sync data - interfaceSync data - interface

The synchronous data port is a ITU compliant interface for data rates of up to 64 kbps.

A 15-way D sub type connector provided the physical interface connections to the external equipment. This interface uses balanced V.11 data and clock circuits and unbalanced V.28 control circuits.


Data interface settingsData interface settings

The data interface can be set to various protocols depending on the requirement:

G.703 Codir – 64kbps (DS-0) co-directional clocking

G.703 Contra – 64kbps (DS-0) contra-directional clocking

Sync Data – 64kbps V.35, V.24 or X.21 (V11).



G703 Codi r G703 Cont r a Sync Dat a Subscr i ber Exchange


Sync data – Rear panelSync data – Rear panel

CONTROL SYNC DATA

G.703LMS

ANTI/O

DATA INTERFACE

LINE INTERFACE

Synchronous Data Port

Back panel synchronous data port


Sync data - Sync data - Functional DescriptionFunctional Description

The external synchronous data is interfaced using U35 (XRT3591) and control signals with U34 (MAX232) transceivers. This provides the correct electrical level for each circuit. The circuits are converted to TTL levels and these are supplied to the FPGA. The FPGA is used to perform all framing functions. These functions are as follows…

Transmit/Receive input/output

Transmit/Receive slip buffering

Transmit/Receive Scrambling/De-scrambling

Transmit/Receive Framing/De-framing


Sync data – Block diagram Sync data – Block diagram

MircoControllerFramerControl

G.703Data

Interface

SyncData

Interface

FPGAFramer

Modem

RS485Bus

ExternalInterface

ExternalInterface

68 kbp/s

To Transmitter

To Receiver

Data

Data

64 kbp/s


Sync data – RTS/CTS operationSync data – RTS/CTS operation

The RTS and CTS signals are used to operate the link when in G.703 or sync data mode.

RTS RTS

CTSCTS

DSR DSR

Request linkup

Status linkup


Data cData clockinglocking

The clock input circuit always uses incoming data clocks signals to sync to. This means the data clock must be sourced, either from the external equipment or looped back from the recovered received (RF Rx) clock.

The modem can be clocked by three different clocks;

Recovered input clock (Sync to Rx) – clock from VCXO synchronised to input clock

Reference clock (Internal Clock) – On board 64 kbps reference clock (4.352 MHz 68).

Receiver clock – Use in telephone mode only


Data clocking diagramData clocking diagram

Receiver64 kHz

64 kHz

Receiver

Transmitter64 kHz

64 kHz

Transmitter

64 kHz InternalRef Osc

Duplexer

Modem /Controller Module

Modem /Controller Module

Duplexer

64 kHz InternalRef Osc


G703 Codi r G703 Cont r a Sync Dat a

Setting data clocking modeSetting data clocking mode

The EX7100 can be set to various clocking modes depending on the data interface selected.

G.703 Codir – ‘Internal reference’ or ‘Sync to received clock’.

G.703 Contra – ‘Internal reference’, ‘Sync to received clock’ or ‘External sync clock’.

Sync data – ‘Internal reference’ or ‘Sync to received clock’ + clock polarities.

FramerPSU Moni t or i ng

Dat a Cl ockBER

Tx Cl ock Source Tx Pol ar i t y

I nt er nal Ref Sync t o Rx

I nt ernal Ref Sync t o Rx Ext Sync Cl k

I nt ernal Ref Sync t o Rx

Nor mal I nver t ed


RS232 Module - InterfaceRS232 Module - Interface

The RS232 option provides 6 EIA/TIA 232E compliant interfaces for standard data rates from 75bp/s to 9600bp/s.

A 36-way CHAMP type rear panel socket provides the physical interface connections for the six Async channels. This interface provides 2 data circuits TxD & RxD and 2 control circuits DTR & DSR

together with a signal ground.


RS232 module – rear panelRS232 module – rear panel

CONTROL SYNC DATA

G.703LMS

ANTI/O

DATA INTERFACE

LINE INTERFACE

RS-232 Interface


Configuring RS-232 interfaceConfiguring RS-232 interface

With the RS-232 option each channel may be configured for either Voice or RS-232 or a combination of both.

RS232Remot e Test s

Al l *Voi ce

RS232


RS232 InterfaceRS232 Interface

RS232Interface

FPGA

CPU

6RS232Data

Intercepted64kbp/s

Data

64kbp/sData

InterceptedRS485Data

RS485Data

LineInterfaceModule

FramerModule


RS232 applicationRS232 application

ENTER

POWER

ALARM

Rx LOCK

Tx ON


GND

EX7100Digital Radio

ENTER

POWER

ALARM

Rx LOCK

Tx ON


GND

EX7100Digital Radio

EX7100 EX7100

PC

PC

Modem

PLC etc.

PC

PC

PBX

SCADAServer

PBX

PBX

Telephone

RS232RS232

RS232

Telephone

RS232 RS232

RS232

POTSPOTSPOTS

POTSPOTS

POTS

RF networksRF networksModule 7.


RF modulesRF modules

The RF is divided in to various sections: Receiver – Single Conversion Superhetrodyne

• Receiver front end – Cavity or helical resonator filters with AGC control.

Transmitter – 16 QAM with Fractional N synth• Power Amplifier – Class AB amplifier with 50dB gain


Universal RF parametersUniversal RF parameters

Various parameters are available user in the EX7100. Listed are the most common:

RSSI – Received Signal Strength Indicator, used for monitoring the strength of the received signal.

Transmit Power output

RF Par amet er sFr amer

RSSITx Power RSSI : 65 dBm

Set Al ar m Poi nt

Tx PowerChan I ncrement

Tx Power 10. 0W

Set Power Level- 106dBm

- 46dBm

1. 25W2. 5W5. 0W10W

RF Par amet er sFr amer


VHF/UHF Receiver ModulesVHF/UHF Receiver Modules

Overview Single Conversion Super Heterodyne design

Sensitivity 10-6BER < 102 dBm (1.8uV) @ Rx Input

Selectable 5 or 6.25 kHz Synthesiser steps.

Choice of VHF or UHF.

Various frequency bands between 138 – 512 MHz.


VHF Receiver FunctionsVHF Receiver Functions

User interface/software selectable operating frequency.

Rx Front-End pre-filters and amplifies the received signal. Also provides protection to the receiver via PIN diode switch.

21.4 MHz IF is mixed with RF.

The IF signal is passed through a series of AGC stages before the carrier is detected.

The signal is then demodulated and then divided into the ‘I’ & ‘Q’ symbols.


VHF front end – Block DiagramVHF front end – Block Diagram


VHF Receiver – Block diagramVHF Receiver – Block diagram


UHF Receiver FunctionsUHF Receiver Functions


Rx Front-End pre-filters and amplifies the received signal. Feedback protection is provided by an Overload detector.

21.4 MHz IF is mixed with RF.

The IF signal is passed through a series of AGC stages before the carrier is detected.

The signal is then demodulated and then divided into the I & Q symbols.


UHF front end – Block diagramUHF front end – Block diagram

Variable Gain Amplifer

(-60dB to -2dB)

AGC1

RX O/L touP module

(0V =O/L, 5V = OK)

Amplifier +20dB

RX overload detector

Amplifier +10dBTunable

BandpassTunable

Bandpass

Amplifier +10dB

RF from Duplexer RF to Receiver

FL101 FL102 FL103U101 U102 U103

Can tolerate approx. +8dB


UHF Receiver – Block diagramUHF Receiver – Block diagramR X f r o mf r o n t e n d M 2 0 1

W 1 0 1

T 2 0 2

C r y s t a l f i l t e r2 1 . 4 M H zF L 2 0 1 T 2 0 3

Q 2 0 2T 2 0 4 U 2 0 1

A G C 2

T 2 0 5U 2 0 2

I F M O DP L 2 0 2

A c t iv eT e r m in a t io n

N o t e :F o r - 8 0 d B m in p u t A G C 2 3 . 0 VF o r - 6 0 d B M in p u t A G C 2 0 . 6 V

D e m o dU 2 0 4

I d a t a

Q d a t a

R V 3 0 1D C o f f s e t

R V 3 0 2D C o f f s e t

U 3 0 1 A & C

U 3 0 1 B & D

U 3 0 2 A

U 3 0 2 B

U 3 0 3 A

U 3 0 4L o ga m p l i f i e r

R V 3 0 3Q u a d n u l l

U 3 0 5 A1 6 k H z

P r e c i s io nd e t e c t o r

U 3 0 5 B

A G C d e m o d

I r e c e iv e

Q r e c e iv e

2 1 . 4 M H zQ 2 0 3Q 2 0 4

X 2 0 12 1 . 4 M H z

6 d Ba t t e n u a t o r

E E P R O M

U 1 0 2

I I C

V C O

W 1 0 2

SM B c o n n e c t o r

( So ld e r e d )


Configuring the ReceiverConfiguring the Receiver

The receivers set frequency can be changed, across the modules band, via the front panel.

RF Par amet ersFr amer

Rx FrequencyPA Temper at ure

Rx 155. 1275 MHz Change Freq


Changing Rx step sizesChanging Rx step sizes

There are 2 synthesiser step sizes are available to the user:5kHz – Common in the USA

6.25kHz – Universally used thought-out the rest of the world


Chan I ncr ementTx Frequency

5 kHz*6. 25 kHz


VHF/UHF Transmitter ModulesVHF/UHF Transmitter Modules

Overview Uses Quadrature Amplitude Modulation (16-QAM) scheme.

Power level adjustable from 1.25 to 10 Watts in 3dBm steps

25 kHz channel bandwidth.

Selectable 5 or 6.25 kHz Synthesiser steps.


Various frequency bands between 138 – 512 MHz.


VHF Transmitter FunctionsVHF Transmitter Functions


‘I’ & ‘Q’ data from the modem is converter into 4 levels (2 x I & 2 x Q components) by introducing DC voltage levels.

Frac N Synthesiser and VCO generated a frequency twice that of the operating frequency.

The 4-symbol ‘I’ & ‘Q’ data is mixed in the QAM modulator with the 2 x RF to produce the operating frequency.

The modulated RF is amplified and filtered then passed to the PA (at a nominal level of -15 dBm) for additional amplification.

Microcontroller on the transmitter module provides control, metering, and RF information for the transmitter, PA, and Receiver/Receiver Front End.


VHF Transmitter – Block diagramVHF Transmitter – Block diagram


UHF Transmitter FunctionsUHF Transmitter Functions


‘I’ & ‘Q’ data from the modem is converter into 4 levels (2 x I & 2 x Q components) by introducing DC voltage levels.

The 4-symbol ‘I’ & ‘Q’ data is mixed in the QAM modulator with the 130 MHz Local Oscillator (IF).

Operating frequency is produced by mixing the IF (130 MHz) with the VCO generated frequency (RF + 130 MHz).

The modulated RF is amplified and filtered then passed to the PA (at a nominal level of -15 dBm) for additional amplification.

Microcontroller on the transmitter module provides control, metering, and RF information for the transmitter, PA, and Receiver/Receiver Front End.


UHF Transmitter – Block diagramUHF Transmitter – Block diagram


Configuring the TransmitterConfiguring the Transmitter

The transmitters set frequency can be changed, across the modules band, via the front panel.

If the transmitters is frequency is changed by greater than ±100kHz it will be necessary to return the duplexer.


Tx FrequencyRx Frequency

Tx 150. 1275 MHz Change Freq


RF Power Amplifier ModuleRF Power Amplifier Module

Overview Maximum 10 Watts (PEP) output at antenna port.

High efficient linear Class AB operation mode


Microprocessor controlled active forced air-cooling system (10 Watt system only).


RF Power Amplifier FunctionsRF Power Amplifier Functions

User interface/software selectable power output.

Class AB operation using MOSFET high gain transistors.

VSWR Bridge used to detect forward and reverse RF power.

Heatsink mounted temperature sensor detects and controls the operation of the two fans. If temperature is between 46C and 60C one fan will turn on. The other will only operate is the temperature rises above 55C. Note: The life of the fans is improved by automatic cycling every two days.


PA – Block diagramPA – Block diagram

RF Amplifier22 dB Gain

RF From TxPL100

RF to DxPL102

Nominal51 dBm

Range 31 - 48 dBmAmplifier Bias

RV101

Directional Coupler

7 poleFilter

REV

dB

Class AB



5 poleFilter

Attenuator 1 dB FWR

Bias Detector

MOSFET Amplifier

BiasRV100

50 ohmsuP Filterfor reduction of

Hamonics

Q100Q101 Q102

Q103A

Q103B

Q104Q105U100

Temp Sense

U101

Bias Supply+15V


Peak Envelope PowerPeak Envelope Power

The complex waveform used in Quadrature Amplitude Modulation system means that the instantaneous power at any in-band frequency can vary considerably. This difference in power between the peak and average values can be broken down into two different components.

Variation in power due to the basic modulation scheme.

Effect of filtering the signal.


Peak Envelope Power Cont’dPeak Envelope Power Cont’d

16 QAM modulation scheme for the EX7100 gives a “peak to average power ratio” factor of 2.55.

The roll off filtering for the EX7100 gives a “peak to average power ratio” factor of 4.7 dB.

Therefore the total value of “peak to average power ratio” is 2.55 + 4.7 dB = 7.25 dB.

If using a Linear ‘Bird’ Wattmeter the measured power will be 7.25 dB lower than the actual PEP.


Sensitivity - BER vs. SINADSensitivity - BER vs. SINAD

Sensitivity indicates the Minimum Discernible Signal (MDS) that the receiver can

detect i.e. Noise floor.

SINAD (Signal + Noise and Distortion) is the common sensitivity measurement

associated with Analogue FM receivers.

The MDS is commonly measured at the 12dB SINAD point. This corresponds to a

4:1 Signal / Noise ratio.

Bit Error Ratio (BER) is used to measure sensitivity in a Digital radio system.

BER is defines as the ratio of erroneous bits in a transmitted or received Binary

stream.

BER is normally expressed as a coefficient and to the power of base 10; for

example, 2.5 erroneous bits out of 100,000 bits transmitted would be 2.5 out of 105

or 2.5 × 10-5.

Installation and commissioningInstallation and commissioningModule 8.


NetworkingNetworking

There are two aspect of the network that must be considered when installing the EX7100.

Telephony or Data Networking

Radio Networking.


Initial link upInitial link up

To initially test the integrity of the link set the terminal to 100% mode. This will activate the transmitter and set-up the link.

Cont rol l erRF Par amet ers

Oper at i on ModeSet Ti me/ Dat e

Ter mi nal 100%*Ter m on Demand Repeat er 100% Rpt r on Demand


Controlling the remote terminalControlling the remote terminal

The remote terminal can be controlled and parameters changed or monitored from the local terminal.


St ar t TestEnd Remot e Test

End Remot e TestTest New Confi g

xx3xxxxx Ant enna Al i gn


Antenna align modeAntenna align mode

The antenna can be roughly aligned using the antenna align mode. This will de-activate the local transmitter while activating the remote transmitter.


St ar t TestEnd Remot e Test

xx3xxxxx Ant enna Al i gn


LoopbacksLoopbacks

Both voice or data channels can be tested by using loopbacks. Two types are available:

Local loopback – the loopback is controlled within the local terminal. Typically used when checking cabling or setting between terminal and user equipment.

Remote loopback – the loopback is controlled within the remote terminal. Typically used to check data or voice integrity across the link.


Enabling data loopbacksEnabling data loopbacks

Any of the three data interface types can be loopbacked.


Loopback

Local Remot e


Enabling voice loopbackEnabling voice loopback

Individual or all voice channels loopbacks can be enabled.

ExchangeRS232

Subscr i berRS232

LoopbackFax/ Dat a Det ect

Al l *off

OR

Site and system planningSite and system planningModule 9.


IntroductionIntroduction

The overall link reliability and BER performance can be affected depending on the quality of the system planning. It is therefore important to take time to plan the site and RF path carefully.

The following will help in calculating the suitability of the RF path


System PlanningSystem Planning

Radio telecommunications systems such as the EX7100 uses the atmosphere as transmission medium between transmitter and receiver. They do so by the propagation of radio waves. Because of this, system performance is affected by the interaction of waves with the earth’s surface and it atmosphere.


Propagation of radio wavesPropagation of radio waves

Propagation effects of interest in digital VHF/UHF radio systems are:

Free space attenuation

Reflection from objects on the earth’s surface (e.g. Mountains, building)

Diffraction by objects on the earth’s surface (e.g. Mountains, buildings

Refraction by the earth’s surface and atmosphere.


Types of lossesTypes of losses

Free space loss

Diffraction or obstruction loss

Transmission feeder loss


Signal attenuation…Signal attenuation…

Is the loss or attenuation of signal between the transmitter and receiver

Signal path loss (dB) = Free space loss (dB) + Diffraction loss (dB)


Free-space lossFree-space loss

Free space loss is determined solely by distance and frequency.

It is the measure of attenuated signal strength due to the unobstructed distance between a transmitter and receiver.

Conform to “Inverse square law”

i.e. If the distance is doubled the signal will only be one quarter of the signal available at the receiver

Loss = Power output (W)

Power received (W)

Or Loss = (power output in dB) – (power received in dB)


Free-space loss calculationFree-space loss calculation

The Free Space Loss is predictable and given by the following formula:

FSL(dB) = 32.45 + 20Log10F(MHz) + 20Log10D(km)

The Free Space Loss at 10km using a 450 MHz system is:

FSL(dB) = 32.45 + 20Log10(450) + 20Log10(10)

= 32.45 + 53.06 + 20

= 100.05 dB


Diffraction lossDiffraction loss

Diffraction or obstruction loss is dependant on the terrain between two antennas.

Losses depend on the frequency and the composition of the obstruction

Losses can also be from the surface of the earth.

Loss = d1 x d2

d1 + d2

Where d1 and d2 are the distance between the two end points and the centre of obstacle projected on the base line


Transmission feeder lossTransmission feeder loss

Transmission feeder loss is dependant on:

The quality of the cable and connectors

The length of cable

The frequency

It is important to choose good quality cable and connectors to reduce the losses.


Link performance predictionLink performance prediction

By determining the path loss and the losses and gains in the cable and at the antenna, it is possible to predict a signal-to-noise ratio at the input to the Duplexer of the receiving terminal.

Higher accuracy can be obtained by using path profiling software such as pathloss.


Typical path profileTypical path profile

EXICOM Technologies Ltd.

PaparoaLatitude 42 24 19.44 SLongitude 171 20 35.37 EAzimuth 220.05°Elevation 822 m ASLAntenna CL 8.0 m AGL

HokitikaLatitude 42 43 26.74 SLongitude 170 58 45.11 EAzimuth 40.29°Elevation 6 m ASLAntenna CL 20.0 m AGL

Frequency (MHz) = 420.0K = 1.33

%F1 = 60.00

Path length (46.33 km)

0 5 10 15 20 25 30 35 40 45

Ele

va

tio

n (

m)

0

100

200

300

400

500

600

700

800

900


Link budgetLink budget

The EX7100 requires a receive signal level of better than –98dBm to ensure BER performance of 1x10-6 however this does not allow for any fade margin. Typically it is recommended to allow a 20dB (or better) fade margin in the link budget calculation which will safely provide better than 99.99% link availability.


Improving transmission levelsImproving transmission levels

In marginal conditions there are a number of steps that can be taken to improve transmission levels.

Adjust antenna height,

Use higher gain antennas,

Use dual-stacked antennas,

Reduce other losses e.g. low loss cable,

Increase transmit RF power,

Install a repeater


Radiated powerRadiated power

In a wireless system, antennas are used to convert electrical waves into electromagnetic waves. The amount of energy the antenna can ‘boost’ the sent and received signal by is referred to as the antennas Gain. Antenna gain is measured in:

1. dBi: relative to an isotropic radiator

2. dBd: relative to a dipole radiator

0 dBd = 2.15 dBi


Radiated power - measuredRadiated power - measured

Some radio authorities set guidelines that must be met in terms of the amount of energy radiated out of an antenna. This ‘energy’ can be measured in one of two ways:

1. Effective Isotropic Radiated Power (EIRP)

measured in dBm = power at antenna input [dBm] + relative antenna gain [dBi]

2. Effective Radiated Power (ERP)

measured in dBm = power at antenna input [dBm] + relative antenna gain [dBd]


Energy lossesEnergy losses

In all wireless communication systems there are several factors that contribute to the loss of signal strength. Cabling, connectors, lightning arrestors can all impact the performance of your system if not installed properly.

In a ‘low power’ system every dB you can save is important!! Remember the “3 dB Rule”.

For every 3 dB gain/loss you will either double your power (gain) or lose half your power (loss).


3dB Rule3dB Rule

-3 dB = 1/2 power

-6 dB = 1/4 power

+3 dB = 2x power

+6 dB = 4x power

Sources of loss in a wireless system: free space, cables, connectors, jumpers, obstructions


System gain/lossesSystem gain/losses

Radio

LOSSCable

Connectors etc

GAIN

Radio

GAIN

Antenna

LOSSCable

Connectors etc

GAIN

Radio

GAIN

Antenna

Radio

LOSSFree Space

Fresnel


Path propagation Path propagation

As the signal leaves the antenna it propagates, or disperses, into space. The antenna selection will determine how much propagation will occur.

It is relatively important to ensure that a path (or tunnel) between the two antennas is clear of any obstructions. Should the propagating signal encounter any obstructions in the path, signal degradation will occur.

Trees, buildings, power poles, and towers are common examples of path obstructions.


Why line of site is not enoughWhy line of site is not enough

While line of site is important it is not the only constraint to good RF path. Direct RF waves will travel in straight line from transmitter to receiver however there are other waves travelling out from this direct wave. These indirect waves will carry on indefinitely if there is no obstruction. But if the RF wave deflects of an obstacle then the signal will be received ‘out-of-phase’ to the direct RF wave causing a reduction in received power (attenuation). The magnitude of the phase cancelling effect is a function of the signal strength and how out of phase the signal is.


Phase cancellationPhase cancellation

In 1821 Fresnel discovered a mathematical formula for calculating this effect. This formula is based on ellipsoidal zones know as ‘Fresnel Zones’. The zones are always described in terms of angles; therefore in Zone 1 the signal will be out-of-phase by 0 to 90º, Zone 2 out-of-phase by 90 to 270º, Zone 3 by 270 to 450º and so on.


Fresnel ZoneFresnel Zone


Fresnel zone boundaryFresnel zone boundary

Site ASite A

Site BSite B

d1

d2

Radius of n th Fresnel Zone given by:

• Fresnel Zone diameter depends upon Frequency and Distances from the sites along axis

• For minimum Diffraction Loss, clearance of at least 0.6F1+ 3m is required

rn

Site considerations Site considerations Module 10.


Site considerationsSite considerations

A number of factors need to be considered when choosing and commission a site.

Tower construction and height

Type of antennas and gain

Polarity of antenna

Type of cable

Lightning protection


Site safetySite safety

Never place an antenna/tower over or near a power line

Check the advantages but also drawbacks of each tower design

Secure the access to the tower (create a safety perimeter, shield the base to prevent climbing, protect guy anchors)

Ground the antenna, the tower and install a lightning protection.


Tower selectionTower selection

Typically there are 3 types of tower constructions:1. Self-supporting triangular – suitable for heights up to 150

meters

2. Guyed triangular section – suitable for heights up to 300 meters

3. Guyed tubular masts – suitable for heights up to 30 meters


Tower Tower

Factors to consider before installing a tower/antenna: The tower must be capable of safely handling the antenna load

as well as environmental loads e.g. wind loading, snow loading etc.

If guy wires are used, allow sufficient space for the guy anchoring point. Typically 60% to 80% of the tower height in distance from the base of the tower.

Ensure that the footings are designed around the soil conditions at the site.

Ensure the installation of the tower and/or antenna complies with the authority regulations.


Antenna typesAntenna types

There are many different types of antennas available today but they most fall into two categories:

Directional:• Yagi - Uda – Typically uses a ¼ wave dipole with multiple

elements, forward and rear of the dipole.

• Log periodic – Can cover wide bandwidths with fairly constant gain. The elements spacing and lengths increase logarithmically from end to end.

Omi-directional – Receives and transmits in all directions.


Vertical or Horizontal polarisationVertical or Horizontal polarisation

Some advantages can be gained but choosing the correct antenna polarisation. However the polarisation method which is chosen will depend on various factors:

Type of path the signal will travel over. Typically if the signal is to travel over water then vertical polarisation should be chosen.

Higher signals levels can be achieved on shorter paths by using horizontal polarisation. Typically interference from ignition noise etc. is lower with horizontal polarisation.

Local authorities regulations and type of licence used.


Antenna Beam Tilt and FillAntenna Beam Tilt and Fill

Antennas mounted on very high towers may need to take into account beam tilt. Beam tilt is needed when a radiating signal's vertical beamwidth is narrowed (by using high-gain antennas), and the areas near the tower location lose service because most of the signal is wasted by broadcasting into open air. The beam must be tilted either mechanically or electrically to steer the signal back into its proper location.

Mechanical beam tilting is relatively easy. The antenna can be mounted slightly less than 90 degrees from the horizontal plane so the tilted beam illuminates the desired service area. However, in the opposite direction, the signal will be pointed toward the sky, reducing the effective service area in that direction of the antenna.

If the signal needs to be "bent" downward in all directions around the antenna site, an electrical tilting method must be used. This is commonly referred to as "null fill". Electrical tilting is produced by controlling the current phase in the antenna itself. Thus, must be done during the antenna's design stages by an engineer with expensive equipment.


Transmission lineTransmission line

Generally all transmission lines used in VHF / UHF installations should be unbalanced coaxial cable. The choice will depend on two factors - frequency and length from radio to antenna. Another consideration is the low VSWR which should be 1:2.1 or better.

Insertion loss is also an important parameter. It is usually specified in dB/foot and is a linear relationship. Therefore, if the specified insertion loss is 8 dB/100 feet, a 20 foot length would have-an insertion loss of about 1.6 dB. Insertion loss also increases with frequency as the square root of the increase. Hence if the frequency is doubled, the insertion loss increases by 40% and will double for a 4 times increase in frequency.


Transmission line comparisonsTransmission line comparisons

Type Frequency MHz Power* Watts Loss dB per 100 ft Diameter inches Rel. cost

RG58 0-3000 45 15-20 0.2" low

RG8/RG213 0-3000 190 9-10 0.4" moderate

Belden 9913 0-1000 275 4-5 0.4" moderate

Times LMR400 0-2000 350 3.5-4 0.4" moderate

1/2" Alum. 0-3000 650 3-3.5 0.6" moderate

1/2" Heliax 0-8000 900 2-2.5 0.6" high

7/8" Heliax 0-5000 2,000 1.25-1.5 1.0" high

* Typical at 1 GHz.


Surge arrestors Surge arrestors

It is imperative that the equipment is protected from high voltage transients such as lightning strikes. Transients can reach the equipment from typically three sources:

Antenna or tower installation

Telephone cabling

AC mains (power lines)


Surge arrestor typesSurge arrestor types

Many different surge or lightning arrestors can be employed to protect the equipment. Below are listed some standard types:

Coaxial surge protectors – Comprise of a gas arrestor housed in a protective casing. Typical max surge rating 20kA

Quarterwave stub protectors – Protects by using a quarterwave stub between the centre conductor and shield designed to pass RF frequencies but prevents lower transient frequencies. Typical max surge rating 40kA.

Electro static discharge (ESD)Electro static discharge (ESD)Module 11.


What is ESD?What is ESD?

Electrostatic Discharge is the sudden discharge of electrons from one surface to another. This happens when one surface builds up more positive or negative electrons than the other, causing an imbalance between the two. Once the differential is sufficiently high enough to break down the dielectric strength between the two surfaces, the electrons will move from the positive to the negative potential.


ESD - DefectsESD - Defects

There are two types of ESD sensitive component defects.

1. Latent defect

2. Catastrophic defect.

Figure 1. Punctured Barrier Junction after ESD test at 4000V


ESD - Human awareness levelsESD - Human awareness levels

Discharge felt if < 3500 Volts

Discharge heard if < 5000 Volts

Discharge seen if < 8000 Volts


ESD - Typical Discharge VoltagesESD - Typical Discharge Voltages

Event Voltages at RH

10% 40% 55%

Walking across carpet 35,000 15,000 7,500

Walking across vinyl floor 12,000 5,000 3,000

Movement not grounded 6,000 800 400

Removing bubble wrap 25,000 20,000 7,000


ESD - Device SensitivityESD - Device Sensitivity

Device Type Threshold Susceptive (Volts)

MOSFET 10 – 100

VMOS 30 – 1800

NMOS 60 – 100

GaAsFET 60 – 2000

EPROM 100 +

CMOS 200 – 3000

JFET 140 – 7000

SAW 150 – 500

Op-AMP 190 – 2500

Schottky Diodes 300 – 2500

Film Resistors 300 – 3000

Bipolar Resistors 300 – 7000

ECL 500 +

SCR 500 – 1000

Schottky TTL 500 – 2500


ESDESD

What can you do to reduce the risk of static damage?

1. Work only on static controlled surface

2. Always use a verified wrist strap connected to the common earth ground

3. Use the correct static shielded bag for transportation.


ESD – Typical ESD workstationESD – Typical ESD workstation

Diagnostics, maintenance and fault Diagnostics, maintenance and fault findingfindingModule 12.


Basic operational checks - PSUBasic operational checks - PSU

Main power supply Check that the output voltages are present. This can be done

either from the front panel, assuming the front panel is alive, or by measuring on each fuse.

F1

F6F5

F3

F4 F2

S K 2 03

P L1 S K 6TB1

S K 3 01R V3 02

R V3 01 S K 2 05


Basic operational checks - ControllerBasic operational checks - Controller

Controller / Modem

For correct operation:• With terminal transmitting into a dummy load, and no received signal:• D501 (modem DC power) should be on.• D8 (framer synchronisation) should be on.• D100, D101, D102 (training sequence) should all be off.• D103 (modem reset) will flash briefly at approx 8 second intervals.• D9 (data errors) may or may not flash.

With an RF signal from a sig gen into receiver:• D100 will turn on, but will reset after 8 seconds.

With correct signal (from other terminal) into receiver:• D100, D101, D102 will turn on sequentially.• Front panel Rx lock LED will light indicating modem lock.


Basic operational checks - ControllerBasic operational checks - Controller

D5 0 1

U2 1

P L8

P L2

U2 0

P L3

P L50 2P L4

D1 0 3D1 0 2D1 0 1D1 0 0

D8

D9U1 0 3

U9

U5

P L9

U2 2


Basic operational checks – ReceiverBasic operational checks – Receiver

Receiver For correct operation:

• Check VCO Loop volts. This can be viewed from the front panel and should be between 0.5V and 4.7V.

• Check VCO output. This should be RF+21.4MHz at a level of approx 10dBm.

• Send a carrier on the receive frequency at a level of –80 dBm. Look at the I and Q reference points on the rear panel control port. There should be an output voltage of approx 3 volts peak to peak.


Basic operational checks – ReceiverBasic operational checks – Receiver

CV501

P L103

P L102

R V2 01

P L20 2IF M OD

CV2 01

R V3 02

R V3 01

R V3 03

P L101

X4 01 R V4 01

T20 4T20 3

T20 2

T20 6T20 7

T20 5

TP 4 0 1LOOP V

CV4 01

P L40 1LO TES T

W 1 01R F IN

R V4 01

LO Out

P L103

P L102

R V2 01

P L20 2IF M OD

CV2 01

R V3 02

R V3 01 R V3 03

P L101

9 .6M H z R E F

CV1 01

T20 4T20 3

T20 2

T20 6T20 7T20 5

LOOP V

W 1 02

W 1 01R F IN

P L10 4

VHF Receiver

UHF Receiver


Basic operational checks – Front-endBasic operational checks – Front-end

Front end Disconnect RF cable to main receiver board. Front End module should have approx. 20 dB gain

S K 1 02

FL10 1CV1 01

CV1 02CV1 03

S K 1 01

P L10 1R F In

R F OutL11 2L11 1L11 0L10 9 L11 3

R V1 01

FL103

P L101

S K101R F In

S K102R F Out

FL101

FL102

VHF Front-end UHF Front-end


Basic operational checks - TransmitterBasic operational checks - Transmitter

Transmitter• Check VCO Loop volts. This can be viewed from the front panel and

should be between 0.5V and 4.7V

• Check VCO output. This should be RF+130MHz at a level of approx 10dBm.

• Put the terminal into align mode. There should be a signal at a level of approx -15dBm out of the transmitter.


Basic operational checks - TransmitterBasic operational checks - Transmitter

P L701P L108

P L106 R V3 01

R V5 02R V5 01CV401

P L10 1

U2 0 1

P L10 4 W 1 02

P L10 5

P L10 3

X1 01

P L108Tx R F out

10M Hz Ref

CV301

260M Hz Out

Tx LO Out

P L103

P L101P L104

S K301

S K303

R V2 02

R V2 01

CV3 01CV3 02

FL30 3

FL30 5

FL30 4

R 1 04 D1 0 2

TP 1 0 1


Basic operational checks - PABasic operational checks - PA

Power Amplifier • PA module should give approx 50dB of gain.

Note: do not operate PA without terminating into a dummy load.


Basic operational checks – Subs/ExchBasic operational checks – Subs/Exch

Subscriber and Exchange board• LED’s next to each DSP should either be on or off – not flashing.

• Going off-hook at the subscriber terminal, should cause the corresponding exchange terminal channel LED to light.

• Sending ringing into the exchange terminal, should cause the corresponding subscriber terminal channel LED to light.


Basic operational checks – SubsBasic operational checks – Subs

D1 0 0

D4 0 0

D2 0 0

U7 0 0

U9 2 1

U9 1 1

U9 6 1

P L90 4 P L90 2

P L90 3

P L90 5

U9 4 1

U9 3 1

U9 5 1

U9 0 0

P L3

D3 0 0

D5 0 0

P L1

P L2

D6 0 0

S W 3 00

S W 2 00

S W 1 00

S W 4 00

S W 5 00

S W 6 00

P L4


Basic operational checks – ExchBasic operational checks – Exch

U9 3 1U9 2 1

U9 0 0

U7 0 0

Ch 6 COIC

Ch 5 COIC

Ch 4 COIC

Ch 3 COIC

Ch 2 COIC

Ch 1 COICP L10 0

U9 5 1U9 6 1

U9 1 1

P L30 0

D6 0 0

D4 0 0 D5 0 0

D3 0 0D2 0 0

D1 0 0

U9 4 1

P L50 0

P L1

P L90 2

P L90 3

P L2


Basic operational checks – Iso PSUBasic operational checks – Iso PSU

Isolated power supply • Check that voltages are present on input and output connectors.


Constellation patternsConstellation patterns


Constellation patterns cont’dConstellation patterns cont’d


Alarm statusAlarm status

Various alarms conditions are monitored and logged. VSWR alarm

TX Power drop

Low RSSI

Synth Loss

PA Temperature

RF EEPROM Fail

BER

Modem Lock

I/P Volts fault

Int. Rail fault


Alarm priorities Alarm priorities

The alarm priorities can be set to display activations on either local or local and remote terminals.

Al ar ms

Al ar m Pr i or i t yLi nk up Ti me VSWR Al ar m

Tx Power Drop Low RSSI Synt h Loss PA Temper at ure RF EEPROM Fai l BER Modem Lock I / P Vol t s Faul t I nt . Rai l Faul t

Low Hi gh


PSU monitoringPSU monitoring

All internal and external voltage rails are monitored as well as input current.

PSU Moni t or i ngExchange

I nput Vol t age+24V Rai l

I nput Cur r ent

Dr aw: 5. 5A

I nput : 12. 6V

System alignmentSystem alignmentModule 13.


Duplexer tuningDuplexer tuning

If the customer (Tx or Rx) frequency is changed by more than ±50kHz the duplexer must be retuned to maintain correct insertion and isolation loss.

Two types of duplexer set ups are employed in the EX7100:

VHF Duplexer – uses a single 6 cavity band pass duplex filter.

UHF Duplexer – comprises of a 4 cavity band pass duplex filter, a band pass, band reject filter and a band reject, band pass filter.


Duplexer tuning requirementsDuplexer tuning requirements

As a digital radio is susceptible to unwanted RF signal it is crucial to adjust the duplexer correctly:

Measurement Preferred Capability Minimum Capability

Transmission: Dynamic range & Isolation

95dB 80dB

Return loss 30dB 20dB

Insertion loss 2dB 2.5dB


Duplexer plots duplex filterDuplexer plots duplex filter

Duplexer filter high pass Duplexer filter low pass


Duplexer plots BPBR / BRBP filtersDuplexer plots BPBR / BRBP filters

Band reject, band pass filterBand pass band reject filter


Duplexer plots – low pass / high passDuplexer plots – low pass / high pass

Low pass – combined filter High pass – combined filter


Transmitter tuningTransmitter tuning

The transmitter must be retuned if the customers frequency is changed by more than:

VHF tuning range - ±1.0MHz

UHF tuning range - ±3.0MHz


Transmitter PCBTransmitter PCB

P L701P L108

P L106 R V3 01

R V5 02R V5 01CV401

P L10 1

U2 0 1

P L10 4 W 1 02

P L10 5

P L10 3

X1 01

P L108Tx R F out

10M Hz Ref

CV301

260M Hz Out

Tx LO Out

P L103

P L101P L104

S K301

S K303

R V2 02

R V2 01

CV3 01CV3 02

FL30 3

FL30 5

FL30 4

R 1 04 D1 0 2

TP 1 0 1


Transmitter filter plotTransmitter filter plot


Receiver front end tuningReceiver front end tuning

The receiver front end must be retuned if the customers frequency is changed by more than:

VHF tuning range - ±1.0MHz

UHF tuning range - ±3.0MHz


Front end PCBFront end PCB

FL103

P L101

S K101R F In

S K102R F Out

FL101

FL102

S K 1 02

FL10 1CV1 01

CV1 02CV1 03

S K 1 01

P L10 1R F In

R F OutL11 2L11 1L11 0L10 9 L11 3

R V1 01


Front-end filter plotFront-end filter plot

Repeater systemsRepeater systemsModule 14.


Repeater configurationRepeater configuration

The EX7100 can be configured as a full duplex repeater to enable the link to operate over greater distances or over difficult terrain.

The repeater is made up of two back to back EX7100 terminals configured as G.703 data channels.

To enable the remote monitoring across the entire link a link must be made between the control port on both terminals.

CONTROL SYNC DATA

G.703LMS

ANTI/O

DATA INTERFACE

LINE INTERFACE

Control port


Software configurationSoftware configuration

Both terminals must be configured as G.703 data terminals:

Interface Codir G.703

Tx data clock: Sync to Rx

Operating mode: Repeater 100% or Repeater on-demand

Link ID: Both terminals must be set to the same ID as the remote terminal.

Practical activityPractical activityModule 15.


Practical activityPractical activity

Objective: Retune tune the EX7100 3MHz form the set frequency and configure to G.703 (DS-0) data mode.

Required material:• 2 EX7100

• PSU

• Data analysers

• Spectrum analyser with tracking generator

• Misc. cables

• System training manual


Duplexer specificationsDuplexer specifications

Fill out the table below with the measured duplexer results

Measurement Your measurement Minimum Capability

Transmission: Dynamic range & Isolation

80dB

Return loss 20dB

Insertion loss 2.5dB


Software settingsSoftware settings

Fill out the spaces below with the steps involved in changing the software.


Tx FrequencyRx Frequency

Tx 150. 1275 MHz Change Freq

Rx FrequencyPA Temper at ure

Rx 155. 1275 MHz Change Freq


Software settings cont’dSoftware settings cont’d


Dat a Cl ockBER

FramerPSU Moni t or i ng


G703 Codi r

Sync t o Rx

G703 Codi r


Software settings cont’dSoftware settings cont’d



Test New Confi g

New Confi g OKUsi ng New Confi g

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EX7100 Training Course - Master Version 1_0

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