Plantronics CA12CD User manual

Part No. 101987-00 Category Code: 97 Revision: C
Product Summary, CA12CD Cordless
Push-to-Talk Adaptor

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1Document Information
This document summarizes features of the CA12CD cordless
push-to-talk headset adaptor. It is intended for customers who
need general information about this product as an aid to their
purchasing and planning decisions. Specific details concerning
installation and use of the CA12CD are available in the CA12CD
User Guide and the Audio-Level Settings Card, both of which are
available online at the Plantronics website.
Portions of this document are based to a large extent on the
Engineering Support Document, “CS50 General Guidelines,”
Revision 1.5, by Steve Cahill.
1.1 Publication History
Revision Date Description
1 27 Mar 06 First release
2 22 Jun 06 Revise
3 20 Jul 06 Charge LEDs were amber
4 9 Aug 06 Add labels to Figure 1
A 2 Oct 06 Production release
B 14 Mar 07 Add CA12CD/A
C 03 Jan 07 Add sections on voice
privacy, range and density,
subscription, and audio
performance; delete
material duplicated in user
guide.
1.2 Document Approval
Author: Blake Cooper 27 Mar 06
Editor Date
Prepared By: Blake Cooper 27 Mar 06
Engineering Date
Approved By: Mike Erbe 27 Mar 06

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1.3 Table of Contents
Titles Page No.
1Document Information 2
1.1 Publication History.......................................................................2
1.2 Document Approval.....................................................................2
1.3 Table of Contents ..........................................................................3
1.4 List of Illustrations ........................................................................3
2Product Description 4
2.1 Summary of Features....................................................................4
2.2 Functional Description .................................................................5
2.3 Product Architecture ....................................................................7
2.3.1 Base Unit.............................................................................7
2.3.2 Remote Unit .......................................................................8
3Audio Performance 8
3.1 Sidetone ..........................................................................................8
3.2 Interference ....................................................................................9
4Range and User Density 9
5Voice Privacy 10
5.1 Frequency Hopping....................................................................11
5.2 Encryption....................................................................................11
6Subscription 12
1.4 List of Illustrations
Titles Page No.
Figures:
Figure 1: Model CA12CD.........................................................................5
Figure 2: Base-Unit Block Diagram ........................................................7
Figure 3: Remote-Unit Block Diagram...................................................8

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2Product Description
2.1 Summary of Features
•Push-to-talk (PTT) switch that is robust and field-proven
•Spare battery pack
•Two charging wells—one for the remote unit, one for the spare
battery pack
•Lithium-ion batteries
•Eight hours talk time, minimum
•Quick Disconnect™ for compatibility with all Plantronics
H-Series headsets
•Receiving coarse- and fine-adjust sensitivity controls
•Selectable sending-sensitivity ranges to emulate carbon, electret,
and dynamic mics
•Sending-sensitivity fine-adjust control
•DECT™ (Digital Enhanced Cordless Telecommunications) radio
operating in the UPCS band (CA12CD) for North-American
applications and full DECT version (CA12CD/A and variants)
for areas such as the European Union and Australia.
•Compatible with most air-traffic-control and
public-safety-dispatch voice switches
•Ten-foot coiled interface cable with PJ-7 connector (other
connectors available upon request)
•LEDs for RF link, PTT, base power, and battery-charging status
•Audible indicators for such conditions as out-of-range, low
battery, and sending- and receiving-sensitivity changes
•Encryption in compliance with USA regulation
45 CFR 164.312(a)(2)(iv), and therefore compliance with the
Health Insurance Portability and Accountability Act (HIPAA).

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Figure 1: Model CA12CD
2.2 Functional Description1
The CA12CD is a cordless push-to-talk (PTT) headset adaptor
made to provide wireless communications and PTT functionality
for Public Safety Dispatch and Air Traffic Control facilities (see
Figure 1). The CA12CD has a Quick Disconnect and is compatible
with all Plantronics H-Series headsets.2The CA12CD consists of a
base unit and a remote unit.
The base has two charging wells, sending- and receiving-sensitivity
controls, status LEDs and a 10-foot coil cord with a PJ-7 connector.
The charging wells accommodate the remote and a spare battery
pack. The LEDs show battery-charge status, power, and PTT status.
The sending controls consist of a configuration switch to emulate
1Unless otherwise specified, all references to the CA12CD also apply to the CA12CD/A and its
variants.
2Examples of H-Series headsets commonly used in air-traffic control and public-safety dispatch
are the H31 StarSet®, H251 SupraPlus®, H171 DuoPro®, and H91 Encore®, along with the noise-
canceling versions of these headsets. Binaural versions of some of these headsets are also
available. Please see the Plantronics website for further information.
AC Adaptor
(North-
American
version)
Console
Interface
Cable
Remote
S
p
are Batter
y
Base
P
J
-7 Connector
Quick
Disconnect

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the outputs of different microphone types and a sending-sensitivity
fine-adjust control. The receiving-sensitivity control selects among
four different sensitivity ranges, and the receiving sensitivity can be
fine-tuned by a control on the remote. The console interface cable
connects to the base via a 6-pin modular connector and is typically
wired on the console end with sending on the PJ-7 tips, receiving
on the sleeves, and PTT on the rings. When the user presses the
PTT switch on the remote unit, a relay is closed in the base that
places a short circuit across the PJ-7 rings. This short circuit “keys
up” the communications console to which the CA12CD is
connected and allows the user to transmit over the communications
radio.
The remote unit has a PTT switch, an On-Off switch with
incorporated LED, a metal belt clip, a receiving-sensitivity
fine-adjust control, and a twelve-inch cable terminated in a Quick
Disconnect to which any Plantronics H-Series headset can be
connected.
The On-Off switch enables audio and PTT. As long as the base is
powered up, the RF link is maintained regardless of whether
audio/PTT is enabled. Even when the base is powered down, the
remote will continue to run so that the link can be reestablished
should the base be turned on again. Therefore, to completely
power-down the remote unit, it is necessary to remove the battery.
The CA12CD/A and its variants operate in the European DECT
band of 1880 to 1900 MHz.
The CA12CD for North America also uses DECT technology, but it
operates in the Unlicensed Personal Communications Services
(UPCS) 1920- to 1930-MHz band.
The DECT protocol is used for its power efficiency, which allows
extended operation from a relatively small battery pack. A new,
freshly-charged battery will provide about eight hours of talk time.

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2.3 Product Architecture
2.3.1 Base Unit
The block diagram of the Model CA12CD base is shown in Figure
2.
Figure 2: Base-Unit Block Diagram

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2.3.2 Remote Unit
The block diagram of the remote unit is shown in Figure 3.
Figure 3: Remote-Unit Block Diagram
3Audio Performance
The CA12CD audio processing is 32k ADPCM, telephony
bandwidth. A wide range of audio levels can be achieved using the
coarse-adjust and fine-adjust controls provided for both the
transmit and the receive channels. See the User Guide and the
Audio-Level Settings card (both available online) for details on
optimizing these controls for the best audio performance.
3.1 Sidetone
For some installations the user may hear distorted sidetone: They
hear their own voice in the headset as they speak, and it sounds
harsh or rattley. Following the steps outlined on the audio-level
settings card should help the user to avoid this problem. The
On/Off
On/Off

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general procedure for avoiding sidetone problems is to avoid
unnecessarily-high transmit-volume levels and to keep the sidetone
controls on the installation—if present—set to their minimum
positions. The sidetone controls may be user-accessible, or they
may be accessible only to service personnel.
The reason for minimizing sidetone from the customer equipment
is due to the delay introduced by the digital architecture (TDMA3)
of the DECT radio link. Sidetone generated in the customer
equipment is delayed by about 20 mS by the time it reaches the
user’s ears. This is enough of a delay to be unpleasant to the user.
Under normal conditions, a local echo canceller in the base stops
sidetone and network-generated echoes from reaching the user, but
if the transmit signal is too high, or if there is non-linear processing
in the sidetone path, sidetone breakthrough will occur, and the user
will hear the distorted audio described above. A sidetone generator
in the remote replaces the sidetone that has been removed by the
local echo canceller.
3.2 Interference
The CA12CD shares its frequency band with other radio products.
Sometimes interference occurs due to other products using the
same band. Interference may result in buzzing or pops in the talk or
listen audio, or irregular mutes of the talk or listen audio, or may
result in shortened range. The following steps may improve the
performance of a CA12CD that is experiencing interference:
•Repositioning the base
•Limiting the distance between the base and the headset
while in use
•Repositioning the interference source, if known
If the CA12CD base or remote is placed within a few inches of a
cellular phone, the CA12CD may experience interference.
Reposition the cellular phone or the CA12CD base or remote to
increase the separation if this problem occurs.
4Range and User Density
Range is as much as 100 feet. The effective limit to range is set by
the onset of audio artifacts as the user gets further away from the
base. Range can be reduced within a building by the obstruction of
interior walls, or by the presence of other equipment operating in
3Time Division Multiple Access

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the CA12CD’s frequency band, or by the presence of a large
number of other CA12CDs in the immediate area.
Range can be maximized by taking the following steps:
•Maximizing the amount of separation between the CA12CDs
•Placing the CA12CDs so that they are separated by items
such as cubicle walls and furniture
•Turning off all unused bases (and removing the batteries
from the remotes to prevent them from discharging)
•Insuring that no other equipment is operating in the same
frequency band as the CA12CD: Interference may come from
systems well outside the coverage area, as the range for
interference is greater than the coverage range
As a general guideline, maximum range will probably be realized
in a low-density installation of 5 units separated from each other by
at least 10 feet. In a high-density installation of 30 units at 18-inch
spacing, the range could be as little as 10 feet. The worst case for
these coverage limits will occur when a user is distant from their
own base but close to other bases or remotes.
In a high-density installation the CA12CD may take some time to
reestablish connectivity with its base when the user returns to the
coverage area after having been out of range. It normally takes a
few seconds for the remote to find the base’s signal as the user
reenters the coverage area, but this process can take a minute or so
in a high-density installation.
Regardless of the installation’s density, if the user has been out of
range for more than 10 minutes, the link will not be automatically
reestablished: In this case, the user will have to press the On/Off
button on the remote unit to reestablish the link.
Predicting the effective range and region of susceptibility to
interference for individual environments and building layouts is of
sufficient complexity as to be beyond the scope of this discussion.
The preceding information is provided as a reference for system
planning, and the performance of individual installations may
vary.
5Voice Privacy
The CA12CD provides excellent security against eavesdropping.
This security is achieved through frequency hopping and
encryption.

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5.1 Frequency Hopping
The CA12CD avoids two users sharing the same channel and
timeslot under normal circumstances because it chooses the best
available channel, and will change channels if the channel in use
experiences interference from another user. In the event of
operation in a high-density installation where no better channel
and timeslot is available, two users near each other and sharing the
same channel and timeslot will experience occasional mutes of the
receive or transmit audio and occasional audio distortion artifacts,
rather than intercepted audio.
The CA12CD uses fixed-rate adaptive frequency hopping during
the idle-locked state, which is when the base and the remote are in
range but audio is not enabled. This was done to ensure that the
base and the remote are compensating for changes in the radio
signal spectrum due to other users and the presence of interferers,
and thus to improve the reliability of the link, but it has the effect of
adding a layer of security. The hop sequence is random, on the
basis of the physical environment.
The CA12CD uses aperiodic adaptive frequency hopping when the
audio link is enabled. The system is aperiodic because in this mode,
rather than changing channels at a fixed interval of time, the system
hops channels whenever there is another user sharing the same
channel and producing interference. In an environment with many
users, this adds a layer of security because users change channels
from time-to-time, rather than staying in a fixed channel. This
adaptive approach offers improved security relative to other
systems which use a single, common and fixed hop sequence.
5.2 Encryption
The protection against deliberate eavesdropping is through user
authentication and 64-bit true digital encryption of voice data
according to the standard algorithm of EN 300 175-7. A description
of the public portion of this encryption algorithm is available
through the website of the European Telecommunications
Standards Institute (ETSI) at www.etsi.org. Individuals and
organizations having a credentialed need for more detail regarding
the encryption scheme should contact Plantronics Engineering
through the Technical Assistance Center. The CA12CD in particular
and the DECT standard in general are considered secure-enough
for commercial applications requiring voice privacy. This assurance
is based on the 64-bit digital encryption of speech and the
internationally-recognized and standardized encryption algorithm
used.

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6Subscription
The CA12CD remote and base are paired uniquely. The process by
which the remote and the base are paired is called, “subscription.”
Please see the User Guide for step-by-step instructions for
subscribing a base and a remote to each other.
The communications protocol permits audio exchange only
between a remote and a base that are paired. The user can
subscribe a new remote to an existing base to create a new pairing,
or an existing remote can be subscribed to a new base, but a base
can be paired with only one remote at a time, and a remote can be
paired with only one base at time. When a new pairing is
established, the old pairing is lost.