Advent Instruments AI-5120 User manual

Telephone
Line Monitor
AI-5120
User Guide
Advent Instruments Inc.
Release 1.2d

Copyright 2011 - Advent Instruments Inc. All rights reserved.
Printed in Canada
Advent Instruments Inc.
111 - 1515 Broadway Street
Port Coquitlam, BC, V3C6M2
Canada
Internet: [email protected]
[email protected]
Web Site: http://www.adventinstruments.com
Telephone: [phone]
Fax: [phone]
Safety Symbols and Terms
When the
!
symbol is present on an instrument it indicates that the operators should refer to the User
Guide for more information.
When the symbol is present it indicates a terminal that is connected to the functional ground of the
instrument.
When the symbol is present it indicates that the surface may be hot. Avoid contact with the surface
of the instrument to avoid burns.
When the
symbol is present near a screw it should be connected to a safety earth ground using a
wire recommended in the User Guide.
Installation Categories
Advent Instruments products are designed for use and to measure electrical signals that are rated
Measurement Category I as described in the International Electrotechnical Commission (IEC) Standard
IEC 606064. The equipment measurement terminals are not designed to be directly connected to the mains
voltage or a voltage source with high transient over-voltages.

Advent Instruments Inc.
Contents
Safety Symbols and Terms ii
Installation Categories ii
1. Getting Started 1
1.1 Introduction 1
1.2 Package Contents 2
1.3 Important Safeguards and Safety Precautions 3
1.4 Powering on the AI-5120 3
1.5 Connecting to the PC 4
2. TRsSim Software 6
2.1 Introduction 6
2.2 For More Information 9
3. AI-5120 Instrument Suite 10
3.1 Introduction 10
3.2 For More Information 12
4. Technical Overview 13
4.1 Block Diagrams 13
4.2 Indicators & Connections 15
4.3 Specifications 18
5. Firmware Updates 20
Appendix A: USB Driver Installation 22
Appendix B: Error Codes 25
Appendix C: Support 27
AI-5120 User Guide i

1. Getting Started
1.1 Introduction
The AI-5120 Telephone Line Monitor is a compact device designed to detect and analyze
various telephony related signals. By sensing the voltage present on the telephone line it
determines the line state (on hook, or off-hook) in addition to detecting common signals
such as DTMF, FSK, and DC line voltage. Working in conjunction with the TRsSim
software on a PC, the AI-5120 becomes a valuable tool in analyzing and debugging
Caller ID and SMS (Short Message Service) data transmissions. Like an oscilloscope,
the AI-5120 can capture and display waveforms showing the various signals present on
the telephone line. However, unlike an oscilloscope, it can also automatically trigger on
events specific to telephony.
Some of the common events that the AI-5120 detects and analyzes are:
• DTMF Dialing
• FSK Caller ID and ETSI SMS Data
• Pulse Dialing
• Ringing
• CAS/DTAS Tones
• On/Off hook, Line Reversals, Open Switching Intervals (OSI)
As a line monitor, the AI-5120 does not go off-hook (seize the line), or generate tones. It
only listens. The impedance presented by the AI-5120 to the telephone line is over 10
Mohm. As such it has little to no effect on any signals present on the telephone line.
The supplied TRsSim PC software provides a high level graphical user interface for
controlling the AI-5120. As events are detected, the software displays timing and
measurement information. In addition, waveforms for each event may be recorded for
display and further analysis. Waveforms can be played back to the AI-5120's BNC
monitor or speaker out, or exported as wave files for analysis using various software
packages. The TRsSim software automatically decodes FSK based Caller ID conforming
to the Telecordia, ETSI, and Japanese NTT standards. It displays the message contents at
either a high level showing the parameter values, or at a low level showing each byte
detected. Additionally, Short Message Service (SMS) following the ETSI ES 201 912
standard is supported. Details of each SMS FSK message can be displayed along with
various signal measurements.
Any signals present on the telephone line may be routed to the AI-5120's rear panel BNC
output connector or speaker/headphone connector. This provides a simple means to pass
signals to external equipment requiring an unbalanced input. A wide range of
programmable filters can be inserted in the signal path helping to reject unwanted signals
AI-5120 User Guide 1

1. Getting Started Advent Instruments Inc.
and isolating the desired signals. Also available on the rear panel of the AI-5120 is a
digital I/O connector. The three digital outputs can be used to notify external equipment
when the telephone line goes off-hook, when ringing is detected and the decoded bit
pattern from the FSK demodulator. By using the two digital inputs, external equipment
can trigger the TRsSim software to record signals present on the telephone line.
While the TRsSim software is included with every AI-5120, the optional AI-5120
Instrument Suite software converts the unit into a spectrum analyzer and digital storage
oscilloscope. The spectrum analyzer operates over a 35 kHz bandwidth with features
such as variable span, peak hold, averaging, and cursor measurements. The DSO portion
of the software supports up to a 5 second memory depth in addition to programmable
triggers, filters, and cursors.
The AI-5120 connects to the PC via either a full speed (12 Mbit/s) USB 2.0 interface, or
a legacy RS-232 communications port. While the TRsSim software functions with either
interface, the use of the USB connection is strongly recommended due to the fast data
transfer rates. The Instrument Suite software requires the USB connection.
1.2 Package Contents
Use care when unpacking the AI-5120 to avoid damage to the instrument and the packing
materials. Retain the packing materials in case the unit is to be transported in the future.
Please inspect the shipping container and the contents for any damage. If visible damage
is present, contact your local sales representative or Advent Instruments directly (see
Appendix C: Support). Keep the shipping materials for the carrier inspection.
The package should contain the following items:
• AI-5120 Telephone Line Monitor
• Full speed USB cable
• Telephone Cord with RJ-11 Connectors
• AC Power Adapter (plug type dependent on ordering part number)
• CD-ROM containing TRsSim software, USB drivers, and Setup software
• AI-5120 User Guide Manual
• TRsSim User Guide Manual
• Software License Key for TRsSim Application
• Software License Key for AI-5120 Instrument Suite (*)
• Calibration Certificate
If any of the above items are missing, contact your local sales representative or Advent
Instruments directly (see Appendix C: Support) for replacement.
* Note, the AI-5120 Instrument Suite (p/n: AI-SS100) is an optional software
program, and not included as part of the basic AI-5120 package.
2 AI-5120 User Guide

1.3 Important Safeguards and Safety Precautions
Please read all instructions and save them for future use. Observe the following
precautions to avoid injury and prevent damage to the AI-5120 or any products connected
to it. The AI-5120 is intended for use by qualified personnel who recognize shock
hazards and procedures to avoid possible electrical shock. The AI-5120 is designed for
use with electrical signals that are rated Measurement Category I as described in IEC
Standard 60664. All connectors and I/O are intended for connection to Category I
sources unless otherwise described in the manual.
• Insure the AC power source is compatible with the voltage and frequency
requirements stated on the label of the supplied power adapter.
• Do not operate the instrument with the case opened.
• Do not allow any liquid to enter the interior of the instrument.
• Observe all terminal ratings to avoid fire or shock hazards.
• Avoid exposed terminals. Do not touch exposed connections when power
is present.
• Do not operate with suspected failures. If damaged is suspected, do not
continue to operate the instruments until inspected by qualified service
personnel.
• Caution To reduce the risk of fire use only a No 26 AWG or larger
telecommunications line cord
• The instrument is intended for use in an indoor laboratory environment with
an altitude not to exceed 2000m. (Pollution Degree 2)
• To clean the instrument, disconnect it from the power supply, and then wipe
down the exterior with a cloth dampened with a mixture of mild detergent
and water. After the instrument is completely dry, the power supply may be
re-connected.
• Refer servicing to a trained personal only.
1.4 Powering on the AI-5120
Before powering on the AI-5120 for the first time, disconnect any cables connected to the
unit. The supplied power adapter automatically adjusts to a wide range of input voltages
and frequencies. However please ensure the AC voltage source is within the limits
printed on the label.
The AI-5120 does not have power switch. To turn the unit on, insert the 2mm plug from
the supplied power adapter into the matching rear panel jack of the AI-5120. Then plug
the power adapter into the mains AC socket. In order to turn off the unit remove the
2mm plug from the AI-5120.
AI-5120 User Guide 3

1. Getting Started Advent Instruments Inc.
RS-232
9 V 300 mA
DCE
A single beep will be heard and all four front panel indicators should briefly illuminate
for less than one second in duration. Following a short delay the "Ready" indicator
should turn on and stay on. The other three indicators ("Communications", "Ringing",
and "Off-Hook") should remain off. Once the "Ready" indicator is solidly on, the unit is
ready for use.
Communication
Ready
Off-Hook
Ringing
Line Bypass
300 V
Peak
CAT
I
A number of checks are performed during the power up cycle. If a fault is detected, the
"Ready" indicator will either flash, or remain off. If it stays off, the fault is serious and
may require that the unit be returned for repair or replacement. In either case, see
Appendix B: Error Codes for more information and possible corrective action.
1.5 Connecting to the PC
The AI-5120 can be connected to the PC by either its RS-232 port or USB 2.0 compliant
full speed (12 Mbit/second) port. Both connectors are present on the rear panel of the
unit.
If using the TRsSim software with the AI-5120, the USB connection is strongly
recommended because of its higher data rate. USB incurs less latency when sending
commands and receiving the waveform data from the AI-5120. However either
connection method operates reliably with the TRsSim software.
USB Driver
The proper drivers must be installed before a USB connection can be established between
the AI-5120 and the PC. The WHQL USB driver files are automatically installed with
the TRsSim application and no further steps should be required.
If the end use does not require the TRsSim application then it is also possible to install
the driver manually.
For detailed step-by-step instructions on installing the driver, see Appendix A: USB
Driver Installation. The following is a summary of the installation procedure described in
the Appendix.
4 AI-5120 User Guide

1. Download the USB driver installation package from our website or from the
CDrom.
2. Double click on the self extracting installer. This normally requires using the
administrator privileges in Vista and Windows 7
3. The installer will decompress the files and prompt you through the steps to
install the driver files.
5. A message should be displayed indicating the successful installation of the two
driver files.
RS-232
The rear panel 9 pin connector of the AI-5120 is configured as a DCE (Data
Communications Equipment) port. As the PC is normally configured as a DTE (Data
Terminal Equipment) port, a straight-though cable is required for the connection. Do not
use a cross-over cable between the AI-5120 and the PC serial port.
The AI-5120's RS-232 data transmissions are fixed at 8 data bits with 1 stop bit and no
parity. The baud rate is adjustable from a default (at power up) setting of 9600 bps to a
maximum of 115200 bps. If a break signal (at least 11 consecutive space bits) is detected
by the AI-5120, it resets its baud rate to 9600 bps. Only three signals are required for
communication. These are Tx Data, Rx Data, and Ground. The Request-to-Send (RTS)
and Clear-To-Send (CTS) signals have no effect on communication. On the AI-5120's 9
pin RS-232 connector, the Data-Terminal-Ready (DTR) pin is directly wired to the Data-
Set-Ready (DSR) pin. As such, if the PC asserts DTR, it can read back that DSR is
asserted as well.
AI-5120 User Guide 5

2. TRsSim Software Advent Instruments Inc.
2. TRsSim Software
2.1 Introduction
The TRsSim software provides a high level graphical user interface to the AI-5120.
Operating under the Windows OS (XP, Vista, Windows 7), it controls the AI-5120 via
either a USB or RS-232 serial connection.
When using the TRsSim software, the AI-5120 is configured as an event recorder. This
means it continually monitors the telephone line voltage for events such as on-hook or
off-hook transitions, line flashes, pulse dialing, line polarity reversals, DTMF digit
detection; CAS/DTAS tone detection, and FSK message detection. Once an event is
detected, any applicable measurements are made and the signal waveform may be
recorded. This information is then transferred to the PC where the TRsSim software is
used to view and analyze the data. Each recorded waveform can range up to 20 seconds
in duration. The TRsSim software can capture multiple waveforms encompassing a total
monitoring time span of 1000 hours.
The graphical representation of the AI-5120 is the main control panel. The TRsSim
software can connect with more than one AI-5120, and each one is displayed in a
separate control panel window. From this window, the current telephone line status is
shown as well as the DC voltage and AC signal readings. In addition, any detected
events are displayed, including their measurement details. From the control panel all of
the settings for the AI-5120 are accessed, as well as viewing event data and waveforms.
The figure below shows an example of the main control panel.
6 AI-5120 User Guide

The top portion of the window displays the current line status and signal level. Both AC
RMS level and DC line voltage are shown. AC signal frequency is displayed if sufficient
signal level is present. Options exist to apply various signal filters (adjustable low pass,
high pass, band pass, and notch) in order to minimize unwanted or interfering tones.
The bottom half of the window shows the recorded events on a time line, along with the
summary information of the events detected. In the example above, the time line is
viewing a 4 second span showing a Caller ID message transmission. Both the time span
and time position is adjustable by clicking on the appropriate buttons. The selected event
in the example above is the detection of a Caller ID FSK message. The basic type of
message is shown along with time intervals to prior and following events.
While the window above shows the basic or summary information regarding the events
detected, further analysis and information is provided by the Data Recorder window. In
the following figure, portions of the captured waveforms for the Caller ID transmission
are displayed.
The AI-5120 records waveforms using two different channels. The first channel is DC
coupled and provides a maximum range of +/- 300 volts. It is used for recording events
such as ringing, on-hook, off-hook, line flash, and pulse dialing. The second channel is
AC coupled with a range of 10 volts peak-to-peak. Sampling much faster than the DC
coupled channel, it records the DTMF, FSK, and CAS/DTAS events.
The figure above shows both channels during the example Caller ID transmission. The
top half (DC coupled) of the window shows the ringing signal prior to the FSK message,
while the bottom half (AC coupled) shows the FSK message. By clicking on the
appropriate buttons, the vertical span, horizontal span, and position of the waveforms can
be changed.
In addition to displaying the captured waveform, the TRsSim software can present
various reports showing more detailed information. This includes measurements for any
DTMF digits, FSK message bytes, Caller ID parameter contents, and SMS message
AI-5120 User Guide 7

2. TRsSim Software Advent Instruments Inc.
contents. The following figure shows the FSK data layer report for the example Caller
ID message.
The TRsSim software includes additional features allowing captured waveforms to be
exported as text or waveform (.wav) files. Waveforms can be played back to the BNC
output connector, speaker output, or any installed PC audio sound card.
Waveform Analysis Software Option: (AI-ET003)
The TRsSim software can include an optional component that provides more advanced
analysis tools. The Waveform Analysis option gives the TRsSim software the following
abilities:
• Show byte and bit level decoding of any FSK waveforms
• More detailed physical layer FSK signal measurements
• More detailed DTMF signal measurements
• Waveform filtering and adjustments
• Waveform measurements
8 AI-5120 User Guide

Note: The Waveform Analysis features are an optional component to the TRsSim
software program, and not part of the basic package.
An example of the FSK byte and bit level decoding is shown in the following figure. As
the recorded signal is zoomed in the window, addition information such as the byte and
bit values are displayed.
A physical layer analysis of the same Caller ID message yields additional information.
The presented report is divided into three parts. The first presents timing information on
the FSK signal. This includes the duration and number of bits or bytes of each section
(channel seizure, mark, data, and mark-out) within the signal. The second part contains
signal measurements such as mark/space tone level and frequency. Additionally the
frequency spectrum during the mark interval is shown. This is used to extract
information about any potential interfering signals. Finally, the third portion of the report
provides a listing of each data byte detected.
2.2 For More Information
Detailed information on the operation of the TRsSim software for the AI-5120 can be
found in the "TRsSim - Telephone Line Monitor - User Guide" document. It shows
how to install and setup the software along with more complete instructions on its use.
This document is included with the AI-5120 package.
As newer versions of the TRsSim software are made available, they are posted on our
web site at:
http://www.adventinstruments.com
Along with software updates, the web site also contains the latest versions of any relevant
documentation.
For technical support regarding the AI-5120 or the TRsSim software, please contact us in
any of the manners listed in Appendix C: Support.
AI-5120 User Guide 9

3. AI-5120 Instrument Suite Advent Instruments Inc.
3. AI-5120 Instrument Suite
3.1 Introduction
The AI-5120 Instrument Suite is a Windows software package allowing the AI-5120
Telephone Line Monitor to operate as a digital storage oscilloscope (DSO) and spectrum
analyzer. The software enables the user to investigate the time domain and frequency
domain representation of signals through an intuitive instrument like software interface.
Note: The AI-5120 Instrument Suite (p/n: AI-SS100) is an optional software program,
and not part of the basic AI-5120 package.
The figure below shows an example of the oscilloscope capturing a DTMF digit
generated by a telephone. Similar to a conventional oscilloscope, controls located at the
right side of the window determine various settings such as vertical scale, horizontal time
base, trigger conditions, and cursors.
The DSO has a record depth of 5 seconds giving it the ability to capture long dialing or
FSK messages, while still being able to zoom into the waveform for analyzing details.
The key specifications for the DSO are presented in the following table:
Bandwidth 100Hz to 10kHz
Accuracy* ±0.2 dBV (100Hz to 10kHz)
Maximum Capture Time 5 seconds
10 AI-5120 User Guide

Maximum Signal Level 4 Vrms (sine wave)
Trigger Sources Signal In, Digital In A, Digital In B
Trigger Modes Auto, Normal, Single
Trigger Slopes Rising, Falling, Both Edges
Measurements Frequency, Peak-Peak Voltage, RMS, Cycle RMS
* Accuracy is specified with no signal filters engaged
The spectrum analyzer can operate simultaneously with the DSO or by itself.
Represented by a separate window, the figure below shows a spectrum of a DTMF digit
generated by a telephone. Cursors 'A' and 'B' indicate the two dominant frequency
components of the signal at 1208 and 698 Hz respectively. The controls to the right side
of the window allow adjustment of the frequency span, center frequency, reference level,
and acquisition settings.
The spectrum analyzer accommodates a maximum span setting of 35 kHz. Additional
features such as peak hold allow it to capture short transient like signals, while spectrum
averaging assists in measuring noise levels or repetitive signals.
The key specifications for the spectrum analyzer are as follows:
Bandwidth 100Hz to 35kHz
Accuracy* ±0.2 dB (100Hz to 10kHz)
±0.5 dB (10kHz to 35kHz)
Maximum Signal Level 4 Vrms (sine wave)
FFT Window Types Rectangular, Blackman, Hanning
Frequency Span Settings (Hz) 35000, 19531, 9766, 7813, 4883, 3906, 2441, 1953,
1563, 976,781, 390, 312.5, 156.3, 62.5
Center Frequency Programmable (Note: not all center frequencies are
available since negative frequencies and frequencies
>35kHz will not be displayed)
Other Features Peak Hold, Programmable Averaging
* Accuracy is specified with Blackman windowing, and no signal filters engaged
AI-5120 User Guide 11

3. AI-5120 Instrument Suite Advent Instruments Inc.
3.2 For More Information
Detailed information regarding the operation of the software can be found in the "AI-
5120 Instrument Suite - Users Manual" document. It provides installation and setup
instructions along with complete information on its use. This document is included with
the software installation and can be accessed by selecting the User Manual command
from the Help menu.
As newer versions of the Instrument Suite software are made available, they are posted
on our web site at:
http://www.adventinstruments.com
Along with software updates, the web site also contains the latest versions of any relevant
documentation.
For technical support regarding the AI-5120 or the Instrument Suite software, please
contact us in any of the manners listed in Appendix C: Support.
12 AI-5120 User Guide

4. Technical Overview
4.1 Block Diagrams
The AI-5120 Telephone Line Monitor consists primarily of a high impedance voltage
amplifier connected to a digital signal processor via two analog-to-digital converters. By
sensing the voltage present on the telephone line, the signal processor is able to determine
the line state and perform measurements on various signals. The following figure shows
the major functional blocks of the AI-5120.
The voltage on the telephone line is measured by an amplifier presenting an input
impedance greater than 10 Mohm to ground for each of the tip and ring leads. The high
input impedance prevents the AI-5120 from affecting the signals present on the telephone
line in any significant manner. Following the amplifier, the signals are split into two
paths. Both signal paths continue through amplifier or buffer stages followed by analog-
to-digital conversion. However one of the signal paths is DC coupled while the other is
AC coupled. The DC coupled channel can accommodate a voltage range of +/- 300 volts
with a sample rate of approximately 1200 sample per second. This channel is primarily
used for detecting DC line conditions (on/off hook, line flash, line reversals) and ringing.
The second channel is AC coupled with a maximum voltage range of 10 volts peak-to-
peak and a much faster sampling rate of approximately 20,000 samples per second. The
AC coupled channel is used for performing DTMF, CAS/DTAS, and FSK detection
along with general purpose signal measurements.
Line
10M
RJ-11
Jack
DAC ADC
ADC
600
BNC Output
Speaker Output
Signal
Processing
DSP
Control &
Supervisory
Functions
USB
Port
RS-232
Port
Digital
In/Out
AC Coupled Channel
DAC
10M
RJ-11
Jack
DC Coupled Channel
Bypas
s
The digital samples from both AC and DC coupled channels are fed into the signal
processing block. It performs all of the detection and measurement for ringing, DTMF,
AI-5120 User Guide 13

4. Technical Overview Advent Instruments Inc.
FSK, and CAS/DTAS signals. In addition the signal processing block can apply various
filters to the AC coupled channel and measure the RMS level, frequency, and THD+N.
Signals sensed from the telephone line may be routed to either the rear panel BNC output
connector, or to the speaker output connector. The BNC monitor has an output
impedance of 600 ohms and can source a maximum voltage level of 5 volts peak-to-peak.
The speaker jack output is meant to drive either a speaker or headphone with an
impedance in the range of 8 ohms to 32 ohms. Its maximum output level is 2.8 volts
peak-to-peak.
The next figure depicts the signal processing flow within the AI-5120. The source of all
signal data is from either the DC coupled channel or AC coupled channel.
Data from the DC coupled channel is routed to three functional blocks that perform line
state detection, ringing detection & measurement, and wave form capture. The line state
detection block determines if a connected TE is either in the off-hook or on-hook state.
In addition it monitors the line for polarity reversals and open switching intervals. The
ring detection block checks for the presence of ringing by measuring AC signal level and
frequency. If a valid ringing frequency (10 to 100 Hz) and level (> 40 Vrms) is detected,
the front panel "Ringing" indicator is illuminated. The last block in the DC coupled
signal path manages the recording of waveforms. Upon detection of various events it
stores waveforms into the AI-5120's internal memory. Normally the waveforms are only
stored in the memory until they are uploaded to the PC by the TRsSim software.
Line State Detection
Internal
Memory
BNC Output
Prog. Filters
RMS Level
Freq. Counter
THD+N
DC Coupled Channel Ring Det. & Meas.
Waveform Capture
DTMF Det. & Meas.
FSK Det. & Meas.
50 / 60 Hz Notch Waveform Capture
Speaker Outpu
t
A
C Coupled Channel
CAS/DTAS Detect
The AC coupled signal processing path operates independently from the DC coupled
path. Prior to any signal detection and measurement, an optional 50 / 60 Hz notch filter
may be applied. This filter helps to minimize the effect of any power line hum pickup.
Following the optional filter, the signals flow to various detection and measurement
blocks. These monitor the incoming data for DTMF, FSK (Bell 202 or V.23), and
CAS/DTAS tones. If detected, any applicable measurements are made and events are
issued to the TRsSim software. The waveform capture block is responsible for storing
AC coupled waveforms in the AI-5120's internal memory. Unlike for the DC coupled
channel, any stored AC coupled waveforms may be played back to either the BNC
monitor output or speaker output jack. Following a programmable filter bank, the AI-
5120 performs continuous RMS level, frequency, and THD+N measurements. The filter
bank contains a selection of programmable low pass, high pass, band pass, notch, and C-
message weighted filters that may be placed in the signal path.
14 AI-5120 User Guide

Both the rear panel BNC monitor output and speaker jack output can select signals from
either before or after the programmable filter bank, or from recorded AC coupled signals
stored in the AI-5120's internal memory. The gain of each output is adjustable over a
wide range.
4.2 Indicators & Connections
The AI-5120 front panel is quite simple and only contains four LED indicators and two
telephone interface RJ-11 jack.
The two left side indicators "Ready" and "Communication" show the status of the unit
and communication activity respectively. Under normal operation the "Ready" indicator
should be illuminated. If it is flashing an internal fault is detected. When the "Ready"
indicator is flashing, the state of the "Ringing" and "Off-Hook" indicators determine the
specific fault condition. See Appendix B: Error Codes for information describing the
fault conditions and possible solutions.
The communication indicator briefly flashes anytime data is either sent to the PC or
received from the PC. Data transferred on either the USB or RS-232 causes the indicator
to flash.
Communication
Ready
Off-Hook
Ringing
Line Bypass
Unit Ready
Communication with Host
Ringing Detected
Terminal Equipment Off-Hook
RJ-11 Connectors
Tip/Ring Interface
300 V
Peak
CAT
I
When the "Ready" indicator is illuminated (no fault condition), then the two right side
LED's show when the AI-5120 has detected ringing or when the line state is in the off-
hook condition. Ringing is detected if an AC voltage exceeding 40 Vrms with a
frequency in the range of 10 to 100 Hz. is measured. The AI-5120 considers the line
state to be off-hook if the measured voltage is below a specified threshold (by default 19
volts)
A telephone line can be connected to either of the AI-5120 front panel RJ-11 jack, as they
are configured in parallel to each other. Typically, the telephone line from the central
office, PBX, or line simulator is connected to one of the RJ-11 jacks, while the terminal
equipment is connected to the other RJ-11 jack.
AI-5120 User Guide 15

4. Technical Overview Advent Instruments Inc.
Line Bypass
Terminal Equipment
CO Line
300 V
Peak
CAT
I
The next figure shows the configuration of the AI-5120 rear panel. The right most 2 mm
jack supplies DC power to the unit.
The connection to the PC (or any other host) is made via either the USB type B connector
or the 9 pin RS-232 connector. It is possible to transfer data to the AI-5120 over both the
USB and RS-232 ports simultaneously. However the TRsSim software is configured to
only use one of the two ports. The 9 pin RS-232 connector is configured as a DCE (Data
Communications Equipment). As such no cross over cable is required when making a
connection to a standard PC serial port. A minimum of three wires are required to make
a serial connection. They are TX Data (pin 2), RX Data (pin 3), and Ground (pin 5). The
AI-5120 can monitor the PC's RTS (pin 7) signal and control the state of the CTS (pin 8)
signal, but does not use them to communicate. The DSR (pin 6) and DTR (pin 4)
connections are internally tied together. The remaining pins (1 and 9) have no internal
connection.
USB
Digital In/Out
Gnd oA oB oC iA iB
RS-232
9 V 300 mA
Monitor
Speaker
2 Vrms
600 ohms DCE
Advent Instruments Inc.
www.adventinstruments.com
Made in Canada
The BNC output connector can be used to monitor signals from the telephone line. Its
source impedance is 600 ohms with a maximum output level of 5 Volts peak-to-peak.
The 3 mm mono speaker jack to the left of the BNC monitor output performs a similar
function, and can drive a speaker or headphone directly. The load impedance should be
in the range of 8 to 32 ohms. Both the BNC output connector and mono audio jack have
adjustable output gain and are controlled from the TRsSim software
To the right of the BNC connector is a 6 pin terminal block. This connector provides 3
general purpose digital outputs and 2 general purpose digital inputs. The sixth pin
provides a ground connection to the AI-5120. The three digital outputs (A, B, C) are in
an open collector configuration. They can each sink up to 25 mA and are pulled high to
+5 volts with a 5.1 kohm resistor. All three digital outputs can be set either high or low.
An additional setting permits output A to mirror the bit pattern decoded by the FSK
demodulator, output B to go high if ringing is detected, and output C to go high if the
connected TE enters the off-hook state. The two digital inputs (A, B) have an input
impedance of 100 kohm. The maximum input level to detect a logic low is 0.8 volts,
while the minimum level to detect a logic high is 2.0 volts.
16 AI-5120 User Guide