Toa EXES-6000 Guide

TOA
EXES-6000
SYSTEM
TOA Corporation
KOBE, JAPAN

PREFACE
This booklet readily explains a working principle of the EXES-6000
system from a standpoint of the entire system and so, does not refer
to the details of the circuits, CPU's or IC's. It is compiled with an
emphasis placed on the descriptions of audio and dial signal flows that
are a base of the system, and the timing of their relative switches,
which are explained by using block diagrams of actual circuits. The
booklet is so compiled that the basic items considered necessary,
such as link, PAM, time division switching, etc. are first explained priot
to entering into the explanations of the actual systems with the aim of
making readers knowledgeable on the system by degrees.

TABLE OF CONTENTS
I. BASIC ITEMS
1. Hands-free System
1-1. Basic Principle of the Hands-free System
1-2. Voice Switch
2. Concept of Speech Link
2-1. Manual Exchange
2-2. Crossbar System
2-3. Space Division and Time Division Methods
3. Principle of Time Division
3-1. RAM (Pulse Amplitude Modulation) Signal
3-2. PAM Signal Generating Process
3-3. Demodulation of PAM Signal
3-4. Sampling Pulse
4. Principle of Time Division Multiplex
4-1. Time Division Multiplex
4-2. Access to Time Division Multiplex
4-3. Time Division Exchange
II. VOICE SIGNAL AND DIAL SIGNAL FLOWS
1. Voice Signal Flow
2. Dial Signal Flow
3. Dial Signal Receiving System
4. Line Memory and Signal Memory
III. VOICE SWITCH CIRCUIT
1. Operation Principle of the Voice Switch Circuit
1-1. Hands-free to Hands-free Mode
1-2. Handset to Hands-free Mode
1-3. Handset to Handset Mode
2. Performance Comparison between New and Old Voice Switches
2-1. Voice Switch Features of Duplex Line Unit for the EXES-5000, the EXES-1000 and the EX-16
2-2. Voice Switch Features of Duplex Link Unit for the EXES-6000
IV. PAGING SIGNAL FLOW
1. Paging System and Signal Flow
1-1. Paging by an External PA Amplifier (Zone Paging)
1-2. Station (Group) Paging
1-3. Block Diagram of Paging Interface (PI) Unit
1-4. Paging Signal Flow
2. Connection for Station Paging (Group Paging)
V. PRINCIPLE OF CONFERENCE FUNCTION
1. Example when One Station is in Conference
2. Example when Two Stations are in Conference
VI. TIE-LINE SYSTEM
1. Dial Signal Flow
2. Voice Signal Flow
VII. DATA TRANSMITTING AND RECEIVING SYSTEM
1. Function Setup
1-1. DIP Switch Setting for the Data Transmitting Unit
1-2. DIP Switch Setting for the Data Receiving Unit
2. Principle of Data Transmitting and Receiving System
VIII. TROUBLESHOOTING
GLOSSARY
Page
1~9
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6,7
8,9
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12
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25~30
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26,27
28-3 0
31~33
34, 35
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36~3 9
36, 37
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40~50
41~47
41~45
46,47
48~50
51~54
55~59
13~16

1. Hands-free System
1-1. Basic Principle of the Hands-free System
Fig. 1 shows a basic principle of the hands-free
system that permits duplex conversation to be
made between the calling and called parties
without using their hands to lift their station
handsets.
Feedback produced between the microphone and
the speaker by the following reasons, however,
makes it impossible for the system to be in actual
use:
a) Both the speaker and microphone are housed
in a small case, causing them to be located in
close proximity to each other.
b) Speaker audio output level is high.
c) Microphone is very sensitive.
Fig.1 Hands-free System
1-2. Voice Switch
To make the hands-free half-duplex conversation
possible by preventing occurrence of such
feedback problem, Toa EXES-6000 system uses
voice switch in its exchange that is able to detect
signal strength information from both lines and to
automatically select the speech line of higher
signal level, while disconnecting another speech
line of the lower signal level. See Fig. 2.
Fig.2 Principle of the Voice Switch
I. BASIC ITEMS

2. Concept of Speech Link
2-1. Manual Exchange
Fig.3 Manually Operated Exchange (8 lines/2 links)
Fig. 3 shows the simplest telephone system.
When an attendant connects between 2 stations
with a strap, speech path can be set up between
them. The strap represents a link, and the number
of links can be increased as the strap increases in
number. You may presume that the attendant
functions as switch in this system.
2-2. Crossbar System
Fig. 4 shows the crossbar method which corres-
ponds to space division method in the classifica-
tion of speech path. The space division method is
mentioned in the next section 2-3. This method,
however, has both the advantage and the dis-
advantage; the advantage is that all stations in a
system can participate in the conversation at the
same time, while the disadvantage is that an
increase in the number of stations will require
greater number of switches as is evidenced by an
example of the EXES-6000 system with 128
stations where the required number of switches
totals
128
2
– 128 = 16,256 pieces.
Fig.4 Crossbar System Exchange (8 lines/full links)
— 2 —

2-3. Space Division and Time Division Methods
a. Space Division Method
Fig.5 Space Division Method (8 lines/2 links)
The method employed in Toa EX-16 system. With
this method, the system can do with the relatively
small number of switches if it is the small system.
But if the system consists of many stations, more
switches are required than with the time division
method referred to in the next section. Supposing
the EXES-6000 system (128 stations/16 links) was
designed with this method, it would require (2 x
128) x (16 x 2) = 8192 switches in total.
b. Time Division Method
Fig.6 Time Division Method (8 lines/2 links)
The method adopted in the EXES-6000 system.
All stations are connected by one of each of
transmitting and receiving bus lines, we call
"highway", and the speech signals are multi-
plexed on the bus lines by means of pulses of
different timing. If we compare this method with
the space division method by taking the same
example of the EXES-6000 system (128 stations/
16 links), the required number of switches is 128
x 2 + 16 x 4 = 320 pieces (this is the actually
required number and not in agreement with a
calculation made from the above Figure. For
details refer to later explanations.), which is far
smaller than that required with the space division
method.
— 3 —

3. Principle of Time Division
3-1. PAM (Pulse Amplitude Modulation) Signal
In order to convert an analog signal such as
speech into a pulse stream, a circuit must sample
it at periodic intervals. The amplitude of the pulses
sampled is proportional to the amplitude of the
original signal at the sampling instant. This pro-
cess is called Pulse Amplitude Modulation or
simply PAM.
3-2. PAM Signal Generating Process
Fig.7 Waveforms for PAM Signal
After being modulated by the sampling pulses
having periodic intervals (Fig. 7-(b)), the analog
signal (Fig. 7-(a)) is converted into such PAM
signal as is shown in Fig. 7-(c). However, the real
pulse intervals are so short that the "spurious"
original analog signal in Fig. 7-(c) and the original
signal in Fig. 7-(a) are almost identical.
Fig. 8 shows the PAM signal generating process.
In its block diagram, the analog signal (Fig. 7-(a))
applied to the input is chopped by the ON and
OFF operation of the switch. The switching is
controlled by the sampling pulses with their high
level causing the switch on and their low level the
switch off. Through this process, the PAM signal
(Fig. 7-(c)) is delivered to the output.
Fig.8 PAM Signal Generating Process
— 4 —

3-3. Demodulation of PAM Signal
Both holding capacitor and lowpass filter are
necessary to demodulate the PAM signal.
(1) PAM signal potential of Fig. 9-(1) at each
sampling instant is held with the holding
capacitor.
(2) Sampling pulse elements contained in the
waveforms of Fig. 9-(2) are eliminated through
the lowpass filter.
(3) Through processes (1) and (2), the PAM signal
is demodulated into such a waveform as is
shown in Fig. 9-(3) which is identical with the
original analog signal.
3-4. Sampling Pulse
If a band-limited signal is sampled by pulses
having regular intervals of time and a frequency
equal to or higher than twice the highest signifi-
Fig.9 Demodulation of PAM Signal
cant frequency, then the sample contains all the
information of the original signal.
— 5 —

4. Principle of Time Division Multiplex
4-1. Time Division Multiplex
The time division multiplex is a method to divide
various signals by time and to place such ti-
me divided signals on a single common line called
highway.
Fig. 10 Time Division Multiplex
4-2. Access to Time Division Multiplex
In Fig. 11-(a) at the right hand side, consider just
how many lines are needed to transmit 4 different
signals A, B, C and D to the outputs 1, 2, 3 and 4,
respectively.
(1) The simplest way is to connect between them
as indicated by dotted lines in Fig. 11-(b) at the
right hand side. This method, however, in-
volves such problem as that the more diffe-
rent signals are used, the more grows the
number of lines.
Fig.11-(a)
Fig.11-(b)
— 6 —

(2) Another connection example like one in Fig.
11-(c) can be considered when you wish to
develop the previous connection in order to
reduce the number of lines. The idea of this
connection is that switches 1 and 2 are
synchronized with each other, through which
signals A to D are transmitted in this order to
each corresponding output. In this event, the
signals delivered to the outputs 1 through 4
are the RAM signal described in section 3-2.
(3) In the example of Fig. 11-(c), one switch has
many contact points, but an actual system
uses an analog switch as shown in Fig. 11-(d),
instead of each contact point so that an
individual pair of analog switches (x and y) is
sequenced in the following order:
When the analog switches x
1
and y
1
synchro-
nized with each other are on, the signal A is
allowed to go through to the output 1, and
likewise when x
2
and y
2
are on, the signal B is
delivered to its corresponding output 2. This
continues till the signal D is sent out to its
output 4, and is again repeated from the
beginning.
Here we show the timing of each switch used in
the system of Fig. 11-(d).
Fig.12 Timing Chart
In the above timing chart, 4 different PAM signals
of Fig. 11-(d) are on a highway (H W line), the state
of which is called "being time division multi-
plexed". In Fig. 11-(d), the signals are quadplexed.
Also, the frequencies (time intervals) of sampled
pulses (i) through (iv) are all the same, which are
the sampling frequency described in section 3-4.
Fig.11-(c)
Fig.11-(d)
— 7 —

4-3. Time Division Exchange
Fig.13 Time Division Exchange Block Diagram (4 lines/2 links)
Shown below is the timing of each analog switch
when a conversation is being made between
stations A and C using LINK No.1 in the above
Fig. 13. (Voice signal flow: Mic A
Fig.14 Timing Diagram
— 8 —
Speaker C,
Mic C
Speaker A)

Here we show the voice signal flow of Fig. 13
where stations A and B are conversing with each
other. For timing of each switch, refer to Fig. 14.
— Timing "1" —
(1) Switches Tx1and Ry1close at the timing "1"
1-4
and Rx
1-4 .
(Marked in red in the Figs. 13 and 14)
(2) The voice signal from the microphone of
station A is transmitted to LINK No. 1 via Tx
1
,
HW-T line and Ty1. The signal between Tx1
and Ty1is the PAM signal. Now that Rx2is left
open at this timing, the signal delivered to
LINK No. 1 will not go beyond this LINK where
the signal is held with a holding capacitor in
order to be demodulated into the original
voice signal. See section 3-3 "Demodulation
of PAM Signal".
— Timing "2" —
(3) Switches Tx
3
and Ry
3
close at this timing.
(Marked in green in the Figs. 13 and 14)
The signal from station A held at LINK No. 1 is
transmitted to the speaker of station C via
Rx
2
, HW-R and Ry
3
. The signal between Rx
2
and Ry3is the PAM signal. The signal from the
microphone of station C is, in the same
manner as described in (1) and (2) above,
delivered to LINK No. 1 and held there.
— Second Timing "1" —
(4) The signal from station C held at LINK No. 1 is
sent out to the speaker of station A in the
same manner as in (3) above.
Since the timings "3" and "4" have no
relations with LINK No. 1, they are omitted
from this example.
— 9 —
among the timings of Ty

1. Voice Signal Flow
Fig. 15 Voice Signal Flow
— 10 —
II. VOICE SIGNAL AND DIAL SIGNAL FLOWS

Assume that stations No. 200 and No. 202 are in
the conversation mode through link No. 1.
a) In this event, voice signal flows from station
No. 200 to station No. 202 as follows:
The voice signal is transmitted to the LM unit
after being frequency-modulated in station
No. 200 ..... demodulated into the original
analog signal in the PLL circuit (analog switch-
es Tx
1
, Ty
1
, Rx
1
and Ry
1
close at the same
timing) ..... passes through Tx
1
..... enters the
DL unit through highway HW-T (in link No. 1,
b) The timing chart below shows actual switch
timings and PAM signal wave forms on HW-T
and HW-R in EXES-6000 systems when the
cross-connection is made between Ty
1
and Rx
2
and between Ty2and Rx1) ..... because Rx2stays
open, the voice signal does not pass through
highway HW-R and is held in the link by a holding
capacitor ..... At the next timing Tx1, Ty1 , Rx1, and
Ry
1
open, and Tx
3
, Ty
2
, Rx
2
, Ry
3
close ..... the
voice signal held in the link passes through Rx
2
..... enters the LM unit through HW-R ..... passes
through Ry
3
, the only switch that remains closed
among ones connected to HW-R ..... sent out to
station No. 202 connected in base frequency band
after being amplified in the LM unit ..... can be
heard from the speaker of station No. 202
simultaneous conversation is being made be-
tween stations No. 200 and No. 202.
Fig. 16 Timing Chart in Conversation Between
Stations No.200 and No.202
— 11 —

2. Dial Signal Flow
Fig. 17 Dial Signal Flow
Station dialing operations cause the pulse stream
corresponding to each key depressed to be
generated in the dial pulse generator, which
The am-
is sent out to the LM
unit of the exchange.
The dial streams are demodulated into the original
pulses with a dial pulse detector in the LM unit,
and then transmitted to the CP unit through the
dial data bus line.
amplitude-modulates the FM carrier
plitude-modulated signal
— 12 —

3. Dial Signal Receiving System
Fig. 18 Dial Signal Receiving System
Let's assume that 202 (station number) is dialed
at station No. 200. The dial pulse detector located
in the LM unit and intended for station No. 200, as
explained just before, delivers the following dial
pulses to the output.
These pulse streams comprising "2", "10" and
in the above Figure, and are
"2" pulses enter
inverted by a transistor. They then pass through
the dial data bus line, and go into Input Port (IP)
No. 0 of the CP unit. The CP unit is cyclically
sending from its Output Port (OP) the scan strobe
signals to each of the 16 LM units in a serial
manner (LM1 through LM16, again LM1 through
LM16 ...... this is repeated), and reads dial data of
8 stations contained in each LM unit in a fraction
of second simultaneously with the transmission
of the scan strobe signals.
— 13 —

The serial pulse streams that went into IP No. 0
are transmitted to both the OC unit and HC unit
after being converted into parallel codes. In the
HC unit, the data from the CP unit is written into
both the line memory and signal memory accord-
ing to the address specified by the OC unit.
Station numbers of the stations in converstations
and the status of each link are written in the line
memory, of which contents become the control
signals for the analog switches of the LM unit.
Signal codes, PIT or non-PTT mode and the
status of each link are written in the signal
memory, of which contents become the control
signals for the analog switches of the SG unit.
— 14 —

— 15 —
Fig. 19 Voice and Dial Signal Flows
— 16 —

4. Line Memory and Signal Memory
Line memory is a 32 words by 8 bits memory
formed from 4 RAM's of 16 words by 4 bits. In
this line memory, station numbers of the
stations engaged in coversations are written
into the addresses that correspond to the link
to be used in the order of a calling side (T) and
called side (R). The data is accessed and read
cyclically word byword in synchronization with
the link change-over switches (Ty
1-
Ty
32
, Rx
1-
Rx
32
) in the DL unit and controls the corres-
ponding time division switch in the LM unit
according to the contents of the data.
Signal memory is a 16 words by 4 bits RAM, in
which signal codes or PTT/non-PTT mode each
link uses are written. Signal switches (Sy
1-
Sy
32
)
of the DL unit's links and time division switch-
es (Sx1-Sx8) in the SG unit are controlled with
the data read out in the same manner as that of
the line memory.
Memory maps of the line memory and signal
memory are as follows:
— 17 —

Contents of the line memory when stations No.
200 and No. 202 are engaged in a conversation
using link No. 1.
Table of Service Signal Tones
— 18 —
T
R
R
T
Duplex
Calling tone
Privacy tone
Busy tone
Dial tone
Zone paging preannounce-
ment tone
All-call paging prean-
nouncement tone
Priority
Holding tone/
Confirmation tone