TECHNICAL
DATA PACKAGE
MODEL BP320
Portable Belt User Station
9300-3507-00
Rev
A
1/95
RTS
'"
(
/-
TABLE
)
PROPRI~ARYNOTICE
OF
CONTENTS
.....................................................
ii
COPYRIGHTNOTICE
PATENT NOTICE ii
UNPACKING
RETURNSHIPPINGINSTRUCTIONS
SECTION 1; DESCRIPTION AND SPECIFICATIONS
1.2 HEADSET REQUIREMENTS
1.3 BP320 SPECIFICATIONS
SECTION
2.1 ELECTRICAL INSTALLATION / GROUNDING
2.2 ELECTRICAL INSTALLATION / POWER
2.3 ELECTRICAL INSTALLATION
2.4 ELECTRICAL INSTALLATION
AND
2:
INSTALLATION
.....................................................
.........................................................
INSPECTION
................................................
............................................
.................................
..............................................
................................................
...............................................
...................................
......
.......................................
/
SIGNALS
1
CROSSTALK CONTROL
......................................
.............................
ii
1-2
1-4
1-4
2-1
2-1
2-1
2-1
2-2
ii
ii
2.5 ELECTRICAL INSTALLATION
2.6 ELECTRICAL INSTALLATION
2.7 USER STATION CONNECTIONS
SECTION
3.1 OPERATING CONTROLS
SECTION
3:
OPERATION
4:
LIST OF' DRAWINGS
/
/
.................................................
................................................
MOISTURE / CONTAMINATION PROTECTION
HUM
PREVENTION
...............................
...............
...........................................
............................................
2-2
2-2
2-2
3-1
3-1
4-1
Page
iii
SECTION
1.1
DESCRIPTION
1:
DESCRIPTION & SPECIFICATIONS
i-)
v
The Model BP320. a portable belt pack stereo user
is
station,
a component used in the
System. Each user station
is
a communications unit
TW
Intercom
along a multi-unit conference bus.
The System Concept Block Diagram, Figure
1-1,
illustrates a user station interconnection, and user
station connection to the system power supply. User
station interconnection can be:
1) Centrally wired, with each cable coming from a
central point or,
2) distributed, where all the user stations are
looped together from one to another, or
3) a combination of both.
The centrally wired interconnection not only reduces
interchannel crosstalk but also allows for easier
expansion into an assignable channel, multi-channel
system.
The BP320 Block Diagram, Figure 1-2, illustrates a
user station functional components, inputloutput
connections and controls.
The BP320 User Station has the following functional
components:
a microphone preamplifier with limiter,
an electronic microphone switch,
two electronic channel delegate switches
two "bilateral current source" line drivers,
two listen volume controls (dual concentric),
two headphone amplifiers,
a stereolmono switch and
a channel selectorltalk delgate switch.
The microphone preamplifierPimiter:
1)
converts the small microphone signal to a strong
line level signal,
2)
conditions the signal strength from loud and soft
talkers to be almost the same and
3) sends the signal to the line via the microphone
switch. The microphone switch transfers the
signal to the two electronic talk switches. These
two switches each drive a bilateral current source
for channels
1
and 2 respectively. A "bilateral
current source" adds signal to the line without
affecting any signals already
on
the line. The
channel selector switch selects on which
channel@) the user will talk and listen. The
BP320 has the capability to talk on either or both
channels without connecting the channels
together.
-
Each "bilateral current source* also
extracts the listen signal from its line and sends it
to the respective headphone amplifier and
volume control. Some of the user's own voice
signal ("sidetone") is also fed to the headphone
amplifier. Each headphone amplifier output
drives the user's headphones. The monaural
fed
switch allows a combined signal to be
to each
of the headphone amplifiers so that a single
earphone can hear both channels.
The user station voltage regulator takes power
from channel
1
regardless of the channel selector
switch setting (exception: local power option
units). The regulator not only supplies regulated
power to the user station, but also prevents
unwanted interaction between the user station
and the intercom line supplying power. The
BP320 call light option works in a special way:
Thr transmitted call light signal follows the
channel delegate switch and may appear on
either or both channels. A call light signal on
either channels triggers the
BP320 call light
receiver.
The
BP320 User Station has four inputloutput
connectors:
1) DYNamic MICrophone type HeaDSeT or
handset.
2) Line INPUT (ties the station to the intercom
line.)
LOOPEXTension (allows another station to
3)
access the line through the first station), (also
called loop-through).
4)
Accessories/External Controls allows:
1)
Remote mic switch (or foot switch)
2) Local powering, and
3) Stereo program input.
Page 1-2
The BP320 User Station has the following controls,
which are described in Section 3:
1) CHannel select switch
2)
A
latching-action MICrophone ON-OW toggle
switch.
3)
A
momentary-action MICrophone ON-OFF
pushbutton switch
4)
A
dual concentric headphone VOLUME
control.
5) CALL LIGHT switchJindicator (Call Light
Option).
1.2
HEADSET REQUIREMENTS
A
wide range of headset types may be used:
Dynamic microphone headset type:
50 to 1000 ohm microphone
25 to 1000 ohm headphone (s)
High efficiency headphones are recommended
because less line current is required from the power
supply. Use headphones with an impedance of 25
8
ohms or greater. Low impedance
ohm headphones
are not recommended. Headphones with good
acoustic isolation (20 to 40 dB) improve
communication in high ambient noise environments,
and allow the user to use the heaphones at a less
tiring lower volume.
In the headset connecting cable, prevent coupling
between the microphone and headphone leads by
using a shielded, twisted pair for the microphone,
and a separate, twisted pair for the headphones. Do
not allow headphone ground to contact microphone
ground or shield. Tie the shield to microphone
ground or
"mic lown. The headset cable can be made
longer when the microphone and headphone pairs
are physically separated. The wider the separation,
the longer the cable length which may be used.
Estimated maximum usable headphone cable lengths
are as follows:
-Single cable, two shielded twisted pair:
10 feet (3.05 m).
-Dual ribbed cable, two shielded twisted pair:
30 feet
(.I4 m).
-Separate cables, shielded twisted pair in each:
50 feet (15.24
m).
-Balanced microphone input:
up to 100 feet (30.48 m).
1.3
BP320 SPECIFICATIONS
Input DC voltage:
DC Current
Quiescent
Operating
Impedance across line:
Ambient Temperature Range
Noise contribution
to 200 ohm line:
Microphone Preamplifier
Input impedance
Source Impedance
Maximum Input Level
Voltage gain:
Frequency Response
20 to 35 volts DC, operating from -200 to +36 volts DC without
damage
40
10 to
milliamps
50 milliamps, typical (wn5 ohm headphones)
100 milliamps, typical(wJ8 ohm speaker)
75 miliamps typical
10,000 ohms typical, 2000 ohms worst case dynamic operation
Operating: 0°C to 60°C
Storage: -55°C to 125°C
One Unit: -75 dBu
Ten Unit: -67 dBu
470 ohms
200 ohms, nominal
150 millivolts
54 dB
100
Hz
to 10,000 Hz, +3dB
Page 1-4
SECTION
2.1
GROUNDING
All
chassis should be connected to earth ground or power
line safety ground, but the
circuit ground should not be directly connected to
"earth" or "chassis" ground. Each user station is
bypassed to its own chassis via a 0.1 microfarad
capacitor to prevent interference from radio stations.
The power supply has a bleeder resistor from circuit
ground to chassis ground (22 kilohms) to prevent
buildup of voltage across the system capacitance. If
the system has no RTS power supply, install a bleeder
resistor at a central point in the system.
2:
INSTALLATION
ELECTRICAL INSTALLATION/
console, rack and wall mounted user station
TW Intercom System
a
be necessary to overcome power losses by
increasing conductor size over long runs (over 1/2
mile (804.67 m).
one BP320 station is
normal #22 AWG conductor size; for a BP320-L,
3/4 mile (1.207
23
ELECTRICAL INSTALLATION/SIGNALS
The required number of conductors to interconnect
user stations is-as follows: (For standard, unbalanced
Typical
km).
operating distance for
1
mile (1.609
km)
using a
TW user stations)
There are two advantages to not "earth" grounding the
circuit ground:
1) The system continues to operate during an
accidental grounding since this can be tolerated by
the system until it can be cleared.
2) Earth currents from other equipment are
prevented from introducing noise into the
Intercom System.
Portable user stations should not arbitrarily be
taped or fastened to metal structures. Grounding
the case of the user station to an arbitrary
structure may introduce large noise voltages due
to local ground currents or the due to the
completion of a "ground loop antenna".
clear
all
earth grounds from the RTS
Intercom System circuit ground. The only ground
should be through the 22 kilohm resistor in the
power supply.
The BP320 receives electrical power from either:
1)
A
system power supply
connector pins
operation) or
2) A local power supply option (12 to 18 volts
A user station requires 18 to 33 volts to be
10,000 ohm bridging impedance across the
powering line, but the station
operate (as in the local power option) from 12 to
33 volts.
range from 20 to 50
mA.
communications signals share conductors, it may
Since, in
2
Model BP320 current requirements
(26
to 32 volts
(t)
and 1 (corn) (2 channel
DC
can
mA;
BP320-L, from 30 to 60
(I),
above, the power and
TW
Always
TW
on line
DC).
a
otherwise
Number of Channels
Use shielded cable to interconnect user stations in
areas of possible electrical interference, (areas such as
those near: digital equipment, high current primary
power conductors ("mains"), transformers,
transmitters and lamp dimmers).
Most two channel applications may use either
standard microphone cable (for convenience) or two-
twisted-pair cable (considerably less expensive than
microphone cable). Standard wire size for the
Intercom System is #22 gauge wire for
interconnection. For permanent installations it is
recommended that each channel should have
individually shielded twisted pair of at least #22 gauge
wire, such as Belden #8723 for 2 channels. For 3
channel installations using XLR type connectors, a
cable of
#8733 may be used (using the 3 drain wires as circuit
ground. For 3 channel installations using terminals
blocks or tag strips, a cable of 3 twisted shielded pairs
such Belden #8777 maybe used (using the 3 drain
wires and one each of the three pair as circuit
ground). This
maintain a low crosstalk figure between channel.
Connect the shield to system common
the shield to chassis, earth or connector shell
ground.
3
individually shielded wires such as Belden
will
Number of Conductors
TW
reduce interference and help
but do not tie
Page 2-1
Figure
3-1
Front Panel
Page
3-1
1
I
I
,
SECTION
RTS
Document
No.
-
4:
LIST
OF
DRAWINGS
AS1428
SD1431
Assembly Diagram, P.C.B CC-501 Layout
Schematic Diagram, Model BP501& BP320 User Stations3
SD1470 Servicing Diagram, Light Signalling Circuit, CC-18SL, Phase
3
Cod~guration
Page 4-1
=?:ST
~~se-!
F
c
->-r
I
sonr,~
P C €0213 ! SACK PA\?-
*->-*
I
Ib.
BP-320
IS
T#E
NEW
MODEL
15.
SEE
SHT
14.
SEE
13.
SEE
IZ.TH\S SLUEMATIC APPLIES TO
11.
ON
I5
Z
PAGE
4
PAGE
3-
PREVIOUS BOARDS, CC-501
CONNECTW
NO
TO
I2
V..
FOR
THE
AW
BP-SO1
1451 F(CC:SOIF).
E,
THIS POINT
SWITCH
TEST FREQUENCIES: ICO hr,lkHzASD lOkrlr
I
CZI
MYMIL.
i
SW
"I
SET LIMITER POT
AND FREQUENCY AT IkHr..VOLUME SAT M'N.
9.CALL
ME43JFLED
IO.OSE.TESTJ~~
.~.€~DI~FOR
VOLTM,E
-5
Z8V
B.CUTTAQLE
SHOWN:
QUIESCENT
DYNAMIC CURRENT: 40mA
6.
ALL
TEST VOLTAGES AND CURRENTS,
INPUT VOLTAGE RANGE AT EXTERNAL POWER
4
oINPUT, J4-I: AS SHOWN, STANDARO-FOR
VOLT INPUTS SUCH AS AUTOMOTIVE
DC
POWER; SPECIAL-LOW VOLTAGE WTTERY
CONF~GURAT~ON FOR
CUT TRACE
@
MINIMUM
ADD Re9 AND/OR
..
2.
CAPACITANCE VALUES ARE SHOWN:
I.
hLL RE5,STORS ARE CARBON
UNLESS OTHERWISE SPECIFIED:
NOTES:
c-."-
WITH
TEST
LWlTCrl
LlqHT OPT TEST DATX.
ATTHIS POINT. USETZSTJ14 IN NOTE.
CALL
~hl
TEST
DC
.SET
TRACES
WRRENT-AO~A;@~SL
AT^
VOLUM~
-
MICROFARADS/VOLTS
20.oM)-'O.IOOkHZATI~O\rpp
AND
TEST
SETUP
UGH? OPTION TESTS
POWEP
CHANNEL SELECT FOR CHANNEL
SUPPLY
(USED
FOR
to
IOOmA (V~51=YlOmVtol~V).
II
to
15VOLT INPUTS:
JUMPER API TO BPI.
OPTION:
R47
FILM,
I
.N
0.3 P05*TIOh,
FORVOLTAGE
BEWEEN
OPTIONS) ARE
=
400-v).
f.
AND
CUT
TRACE^),
~Vf&TT,iS'/.
(r3d8).
10%.
lt.84
AlRCRm
,SET
lav
mc
7..
.i
I
Loading...