DFT120 Manual - Digital Feedback Terminator - Business Telecom ...

Model DFT120
Digital Feedback Terminator
The Bogen DFT120 Digital Feedback Terminator provides high quality recording
and playback of audio pages. The DFT120 breaks the acoustical feedback loop
created by the telephone handset and paging speaker. The page is first recorded
and then played back as soon as the source handset has been put on-hook.
High capacity paging is accomplished by the DFT120’s record during playback,
and page stacking capabilities. The DFT120 can record up to 8 pages during playback
and has 2 minutes of audio memory. The maximum length of any page is
30 seconds.
Features
• 2 minutes of total audio memory.
• Recording a message while another is being played.
• Stack up to 8 messages for playback.
• Loop start or dry loop input modes.
• Multiple Record and Playback modes.
• Pre-page tone available.
• Adjustable delay times between messages.
• Message repeat function.
• Message abort and stop controls available.
• Transformer isolated audio output, selectable 8 or 600 ohm.
• Plugable terminal strip for easy installation.
• Simple dip switch setup of operating modes.

© 1998 Bogen Communications, Inc.
50 Spring St., Ramsey, NJ 07446
54-5036-02
9902 Printed in USA
All rights are reserved. No part of this document may be photocopied, reproduced,
or translated to another language without the prior written consent of
Bogen Communications Inc.
Notice: The information contained in this document is subject to change without
notice and should not be construed as a commitment by Bogen
Communications, Inc.
Bogen Communications, Inc. assumes no responsibility for any errors that
may appear in this document nor does it make expressed or implied warranty
of any kind with regard to this material, including, but not limited to,
the implied warranties of merchantability and fitness for a particular purpose.
Bogen Communications Inc. shall not be liable for incidental or consequential
damages in connection with, or arising out of the furnishing, performance, or
use of this document and the equipment which it describes.
Warning: Changes or modifications to this unit not expressly approved by the
party responsible for compliance could void the user’s authority to operate the
equipment.
Bogen® is a registered trademark of Bogen Communications, Inc.

Contents
General Safety Instructions . . . . . . . . . . . . . . . . . . . . .2
Callouts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3
Packing List . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3
Audio Connections
Audio Input Connections . . . . . . . . . . . . . . . . . . . . . .4
Audio Output Connections . . . . . . . . . . . . . . . . . . . .4
Control & Status Connections
Control Input Connections . . . . . . . . . . . . . . . . . . . . .5
Status Connections . . . . . . . . . . . . . . . . . . . . . . . . . .6
Changing Status Contacts . . . . . . . . . . . . . . . . . . . . .6
Settings and Controls
Output Volume . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7
Mode Setting Dip Switches . . . . . . . . . . . . . . . . . . . .7
Operation
General Operation . . . . . . . . . . . . . . . . . . . . . . . . . . .9
Record Activation . . . . . . . . . . . . . . . . . . . . . . . . . . . .10
Playback Control . . . . . . . . . . . . . . . . . . . . . . . . . . . .10
System Connection Diagrams
Loop Start Trunk & PCM2000 . . . . . . . . . . . . . . . . . .12
Analog Ring Up Line & PCM2000 . . . . . . . . . . . . . . .13
Page Port Interface & PCM2000 . . . . . . . . . . . . . . . .14
Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15
Warranty & Service . . . . . . . . . . . . . . . . . . . . . . . . . . . .16
1

General Safety Instructions
Follow these basic safety precautions when using the system:
1. Read carefully and understand all instructions.
2. Follow all warnings and instructions marked on the product.
3. DO NOT place the product in a closed enclosure or cabinet unless
proper ventilation is provided.
4. Never spill liquid on the product or drop objects into the ventilation
slots and openings. Doing so my result in serious damage to the
components.
5. Repair or service must be performed by a factory authorized repair
facility.
6. Use the provided UL/CSA approved power pack.
7. DO NOT staple or otherwise attach the power supply cord to
building surface.
8. DO NOT use the product near or in wet or damp places, such as
wet basements.
9. DO NOT use extension cord. Install within 6 feet of a grounded
outlet receptacle.
10. DO NOT install during lightning storm.
11. Never touch un-insulated wires or terminals unless the unit is
disconnected from both power and the rest of the phone system.
12. Use Caution when installing or modifying control lines.
13. The unit must be securely attached to a wall board, rack or
table-mounted.
CAUTION
If any wiring from the system leaves the building premises,
you must use proper electrical protectors.
FCC Notice
This equipment has been tested and found to comply with the limits for a Class
A digital device, pursuant to Part 15 of the FCC Rules. These limits are
designed to provide reasonable protection against harmful interference when
the equipment is operated in a commercial environment. This equipment generates,
uses, and can radiate radio frequency energy and, if not installed and
used in accordance with the instruction manual, may cause harmful interference
to radio communications. Operation of this equipment in a residential area is
likely to cause harmful interference in which case the user will be required to
correct the interference at the user’s own expense.
2

Callouts
1
2 3
4
5
6 7 8 9
10
1. POWER - Green LED indicates unit is receiving power.
2. AUDIO IN - RJ11 jack for both loop start audio and dry audio input sources.
3. Output Impedance Selector - Select either 600 ohm @ +4dBm or 8 ohms
@ 0.125 Watts.
4. AUDIO OUT - RJ11 jack for audio output signal and status contact.
5. Unit Status Indicators - Indicates whether the unit is “in-use” and if it is
recording or playing back a message.
6. DC Power Supply Jack - 12VDC supply connects to this jack.
7. Input Type Selector - Selects either loop start (LS) or dry loop (DL) audio
input type.
8. VOLUME - Output volume control.
9. Setup Switches - Dip switch settings control unit feature operation.
10. I/O Connector - Various control inputs and status outputs are available at
this connector. All I/O connections are electrically isolated
from the unit’s chassis.
Packing List
The following items are included in the DFT120 package:
1 - DFT120 Unit
1 - Power Supply (12VDC, 1A)
1 - User’s Manual
2 - Mounting Screws
3

Audio Connections
Audio Input Connections
RJ11 style connector, 6 Position:
1. Not used.
2. Common for Record control
input (pin 5).
3. Ring / Audio in
4. Tip / Audio in
5. Record control input, connect to
ground (pin 2) to start page
recording.
6. Not used.
Input Mode Switch:
DL - Dry Loop position. For operation with phone system paging ports.
Requires dry contact output (connects to pins 2 & 5) for controlling
the recording of pages and a dry audio (no DC voltage) source
(connected to pins 3 & 4). If contact closure is not available, DTMF
or Audio start features can be used to control recoding, see page 7
for details.
LS - Loop Start position. For operation with Loop start trunks and
systems that require loop current to operate. Loop current draw from
the DFT120 will start the recording (connect to pins 3 & 4). See page
7 for details.
Audio Output Connections
RJ11 style connector, 6 Position.
1. Not used.
2. Play status contact common
3. Audio Output (-)
4. Audio Output (+)
5. Play status contact
6. Not used
Note: Play status contact changes states when the unit is playing a page.
Type of closure (normally open or closed) is selectable, see page 6
for details.
Output Impedance Switch:
8 - 8 Ohm position. Will supply up to 0.125 watts of output signal
(transformer isolated) into an 8 ohm load (connect to pins 3 & 4).
600 - 600 Ohm position. Will supply up to +4dBm of output signal
(transformer isolated) into a 600 ohm input (connect to pins 3 & 4).
4

Control & Status Connections
Control Input Connections
These control inputs allow external devices
or switches to control the operation of the
unit. No connections to these controls
required when the unit is set for Automatic
Playback (see “Play mode” setting, page 8).
All Controls Inputs are optically coupled for
electrical isolation.
COMMON (Terminals 1 & 3)
All control inputs are operated by connecting them to one of the COMMON
terminals.
ABORT (Terminal 2)
When the ABORT input is activated, the message which is being recorded
will be immediately halted, any recorded data discarded, and the busy-back
tone sent to at the audio input. The busy back tone will be output for as
long as this ABORT input is held active.
Note: The ABORT input has no effect on the playback of messages.
STOP (Terminal 4)
When the STOP input is activated, any messages being played will be
stopped and discarded. If there is another message in the stack, it will be
played next. The STOP command has no effect on the record process. If
the unit is recording at the same time it is playing, a STOP command will
only stop the currently playing message, the recording process will not be
affected. The unit will wait for the STOP input command to be removed
before playing the next message in the stack.
PLAY (Terminal 5)
When the DFT120 is in automatic playback mode this input will have no
effect. When the manual playback mode is selected (see page 8), this input
will be necessary in order to playback the messages once they are recorded.
A momentary contact closure will initiate the play sequence. Other contact
closures, while the unit is playing, will be ignored. A maintained connection
to COMMON will cause the unit to automatically play after record.
RECORD (Terminal 6)
This input is also available on the Audio Input RJ11 connector. The Record
input is used with a dry loop type of input. Maintaining the connection to
COMMON is necessary while recording a page. When the connection is
opened, the unit will immediately stop recording. The recorded message
must be a minimum of one second in length, any message shorter than this
will be deleted.
5

Control & Status Connections
Status Connections
Three status contacts provide feedback about the operation of the DFT120. The
contacts are electrically isolated from the rest of the unit.
IN USE (Terminal 7 - Common, Terminal 8 - N/O*)
This contact is active whenever the DFT120 is performing any function.
This includes recording, playing, pauses, delays and recording access
tones.
PLAYING (Terminal 9 - Common, Terminal 10 - N/O*)
This contact is active while the DFT120 is playing back a page. It will be
active during the pause between the message repeats but not during the
delays between different messages within the play sequence.
RECORDING (Terminal 11 - Common, Terminal 12 - N/O*)
This contact will be closed while the DFT120 is actually recording audio
data into memory. Because of the unit’s audio and DTMF triggering
modes, the unit may not actually start recording at the same time the
record control input is made active.
* The contacts are set for normally open (N/O) when a function
is not active and closed when the function is active. They can
be changed so that they are normally closed and open when
active, see below.
Changing Status Contacts
The DFT120 is factory configured with all status contacts set for normally open
operation (N/O), closed when active. To change any contact:
1. Disconnect the power supply and remove cover.
2. Locate desired status relay (see figure below).
3. Set the relay’s jumper across pins 1 & 2 for N/O operation or across
pins 2 & 3 for N/C operation.
4. Replace the cover and reconnect power supply.
Jumper installed
for N/O Operation
K3
In Use
K2
Play
K1
Rec
Jumper installed for
N/C Operation
1 2 3
JP-3
1 2 3
JP-2
1 2 3
JP-1
6

Settings and Controls
Output Volume
The output volume control adjusts the level of signal
reaching the input of the paging system. This
control should not be set near the extremes of its
rotation. Too much signal can overdrive amplifier
inputs and distort DTMF tones. Too low a setting
causes poor sound quality and a low signal to
noise ratio.
Mode Setting Dip Switches
The DFT120 is designed to have several functions
programmed by the user. These adjustments
are made by setting dip switches.
The DFT120 features and switch settings are
described below.
Note
Cycle the power to the unit after making
any changes to the dip switch settings.
Changes will not take effect until the power
has been cycled.
Record Activation Method - 1,2
Selects the method by which the
DFT120 will start recording a page
message. Choose from the following:
Loop current (default), Voice activation
or DTMF activation.
Note: Contact closure activation always
available regardless of switch settings.
DTMF Tone Stripping - 3
Selects whether a repeated page will
have any DTMF tones deleted.
DTMF tones recorded at the beginning
of an audio message are typically used
for zone control purposes. A repeated
page normally should not contain these
tones.
1 2 Record Activation
Off Off *Loop Start
Off On Audio Sense
On Off DTMF
On On Not Used
3 DTMF Tone Stripping
Off *Active
On Not Active
Note:
Off - UP
On - Down
* - Factory Setting
7

Settings and Controls
DTMF Tone
Stripping Method - 4
Selects how the DTMF tones coming
from the audio input during recording
are handled.
Tones can be stripped at the beginning
only or anywhere in the message. If the
tones are stripped in the middle of the
message, anything recorded prior to
the tones will be deleted. Only the portion
of the message following the tones
will be played.
DTMF Allotment - 5,6
Selects number of DTMF tones a message
can contain.
Most paging systems require a specific
number of tones for paging zone selection.
If more than that number of tones
is detected by the DFT120, it will abort
the recording.
“# #" Abort Enable - 7
Selects whether 2 “#” DTMF tones will
cause a page recording to be aborted.
This would allow a caller the ability to
discard a recording and avoid having it
played. The “#” button needs to be
pressed twice within one second to
cause the abort.
PLAY Mode - 8
Selects whether the DFT120 will automatically
play messages after they
have been recorded or have an external
device control playback through the
uses of the PLAY control input.
Pre-Page Tone - 9
Selects whether a tone will be generated
prior to message playback or not.
This is used to alert the listeners to
pages. The tone is generated before
each new message playback, but not
before repeats of the message.
DTMF Tone
4 Stripping Method
Off *Strip only at start
On Strip anywhere then
restart recording
5 6 DTMF Allotment
Off Off *Unlimited
Off On 4 Tones
On Off 3 Tones
On On 2 Tones
7 “# #” Abort Enable
Off *Active
On Not Active
8 Play Mode
Off *Automatic Playback
On Manual Play Control
9 Pre-Page Tone
Off *No Tone
On Generate Tone
8

Settings and Controls
Number of Plays - 10
Selects whether the DFT120 will play a
page message once or twice before
moving on to the next message.
Delay Between Plays - 11, 12
Selects the amount of time to wait
between between page message playbacks.
The selected delay will be
inserted between each message in the
playback sequence as well as between
any repeats of each messages.
10 Number of Plays
Off *Play page one time
On Play page twice
11 12 Delay Between Plays
Off Off *1 Second
Off On 3 Seconds
On Off 5 Seconds
On On 10 Seconds
Operation
General Operation
The DFT120 provides three important functions:
1. Prohibits any acoustical feedback by breaking the audio loop between
microphone and speaker.
2. Automatically repeats each page for better intelligibility.
3. Stacks up to 8 pages with the ability to record new pages while playing
back previously recorded ones. This is done on a first-in first-out basis.
The DFT120 is designed to operated in either externally controlled or automatic
modes. For most paging applications the automatic mode can be used. The
automatic mode requires a minimum of installation time because it requires only
2 connections, one to the paging audio source and the other to the paging system.
The setup switches are factory set for the most commonly desired operating
features.
The DFT120’s operation can also be controlled by external equipment if necessary.
A group of control inputs and status outputs provide great flexibility for
interfacing with external equipment. All control inputs are opto-isolated and the
status output contacts are isolated from the chassis and each other. Further
flexibility is provided by allowing the condition of the status contacts to be
changed from normally opened to normally closed.
Another of the DFT120’s important features is its ability to detect, regenerate
and strip-out DTMF tones in messages. Detecting and regenerating DTMF
tones is far superior method than recording DTMF tone when zone control information
needs to be included in paging messages. Stripping DTMF tones out of
the message on the repeat of the page eliminates the possibility of zone control
tones being heard over the paging system.
9

Operation
Record Activation
There are several methods to initiate a recording. Changes in activation modes
cannot be made without changing the particular dip switches and cycling the
power supply.
Loop Start, 2 Wire - The DFT120 will source talk battery to the ring and tip
and begin the record function when loop current draw is sensed. When
loop current draw has stopped the DFT120 will end the recording.
Dry Loop, 4 Wire - This mode requires a separate contact closure pair to
control the page recording. A second pair of wires supplies a dry audio
signal (no DC voltage) to the record input.
Audio Sensing - If no contact closure is available to initiate recording the
audio sense mode can be used. This mode detects the presence to
audio and starts recording. The recording will stop when no audio is
detected for 3 seconds.
DTMF Activation - If no contact closure is available to initiate recording and
audio sensing is not desired (for more control over the start of recording),
the DTMF activation mode can be used. Recording will begin when any
DTMF tone is detected and stop when no audio is detected for 3 seconds.
Playback Control
The DFT120 can be set to automatically play the recorded pages as soon as
possible without any external intervention (Play mode dip switch, page 8).
However, external control may be needed in applications where the DFT120
may not be the only device feeding the paging system. The external device may
control either or both of the recording and the playback functions. Typically the
playback function is controlled by the external device. The Play mode dip switch
must be set for Manual operation to allow external devices to control playback.
Recordings are initiated using any of the activation methods above, but the
external device controls when they are played back. The unit will record and
stack, up to 8 messages into memory, while waiting for a PLAY activation from
an external device. When a “Play” activation is detected, all of the stacked
pages are played in the order they were recorded.
In addition to record and play control the DFT120 also allows message playbacks
to be stopped and recordings to be aborted.
When a STOP command is detected, the unit will stop playback of the current
message and drop it out of the play sequence. Once the stop command has
been removed, the next message in the stack will be played in its entirety. The
stop command has no effect on the recording of messages
10

Operation
The abort command can be used to stop and discard any message that is currently
being recorded. A busy tone is sent back to the input to indicate to the
person making the page that their message has been aborted. The busy tone
will continue for as long as the ABORT input is active. Message playback is not
affected by the use of the abort command input.
11

System Connection Diagrams
Loop Start Trunk & PCM2000
The DFT120 can directly interface with a PBX loop start trunk. The input mode
switch must be set to the LS position. These PBX interface connections can be
used regardless of the device to which the DFT120’s output is connected. In
this drawing the PCM2000 telephone input module is shown connected to the
DFT120 as an example.
Connection of DFT120 for Loop Start Trunk Access and to PCM2000
12

System Connection Diagrams
Analog Ring Up Line & PCM2000
A TAMB telephone access module must be used to connect the DFT120 to analog
ring up line. The input mode switch must be set to DL position. The
DFT120’s output can be connected to any paging equipment. The PCM2000 is
shown here only as an example.
Connection of DFT120 for Analog Ring Up Access Using
TAMB Interface Module and to PCM2000
13

System Connection Diagrams
Page Port Interface & PCM2000
The DFT120 interfaces directly to PBX page ports. The input slide switch must
be set to DL for this application. If the page port has no contact closure, the
DFT120’s VOX activation feature can be used to control recording and playback.
The DFT120’s output can be connected to any paging equipment. The
PCM2000 is shown here only as an example.
Connection of DFT120 for Page Port Access and to PCM2000
14

Specifications
Audio Memory Capacity: 120 Seconds
Maximum Message Length: 30 Seconds
Message Stacking Capacity: 8 Messages
Audio Sampling: 12 Bit word at 16KHz
Frequency Response: 100Hz to 6.8KHz +/-3dB
Distortion: < 1.0% (THD max.)
Signal-to-Noise Ratio: 60 dBr
Dynamic Range: 60 dBr
Audio Input:
Type — Loop start trunk or 4-wire dry loop
Connector — RJ-11 (6 position)
Audio Output:
Type — Transformer isolated, unbalanced
Impedance / Power— 8 ohms / 0.125W or 600 ohms / +4dBm
Connector — RJ-11 (6 position)
Controls & Switches: Volume
Input type (loop start / dry loop)
Output impedance (8 or 600 ohm)
Setup dip switches (bank of 12)
External Control Inputs: Record, Play, Stop
Status Outputs: Record, Play, In Use
Status Contact Rating: 24VDC, 1A
LED Status Indicators: Power, Play, Record, In Use
Protective Fusing: 0.6A, Internal automatic reset
Power Consumption: 12VDC / 350 mA (typical)
Dimensions: 10”W x 1.5”H x 6.5”D
Shipping Weight: 6 lbs.
15

Warranty & Service
Warranty
Bogen Communications, Inc. warranties the DFT120 against all defects in
material and/or workmanship and agrees to remedy any such defect at no
charge provided that the defective unit is returned, transportation prepaid, to
Bogen Communications’ service department. This warranty extends for one
year from data of installation or initial use, provided that this period shall not
exceed 18 months from the date of manufacture. Any product which has been
repaired or replaced shall be similarly warranted as to such repair or replacement
for the remaining warranty period of the product originally installed or 90
days from date of repair or replacement, whichever is longer.
Service
The Bogen DFT120 is not a field serviceable product and customers are
encouraged to return the product to Bogen Communications’ service department
for repair. Bogen’s service department can be reached at (201) 934-8500
Monday through Friday 8:30AM until 5:00PM Eastern time.
If you are shipping the unit for repair under warranty, pack it in the original shipping
container or similar container and ship it to the address below prepaid.
Include a letter stating the problem and proof of purchase showing the purchase
date. The product will be promptly repaired and returned to you freight prepaid.
For service after the warranty period has expired, ship it to Bogen
Communications as above. Be sure to include your name, address and telephone
number in the letter. Bogen will contact you with an estimate of repairs
before proceeding with any work. Return of equipment not in warranty will be at
the owners expense.
Bogen Communications Inc.
Service Department
50 Spring Street
Ramsey, NJ 07446
16

50 Spring Street, Ramsey, NJ 07446
Tel. 201-934-8500, Fax: 201-934-9832
http://www.bogen.com