The E2000 has been adapted to
provide the standard paging system as a data stream for the satellite
based Hutchison paging system. This system services rural communities
via a broadcast satellite link to remote paging stations.
Traditionally the output of the E2000 has been
analogue modem tones in combination with the PURC station control tone
set.
(see Intra-system Configuration) The satellite system most resembles
the Adelaide, Canberra systems where two frequency channels are combined
and switched in a simplex pattern onto a single carrier or bearer link.
In the Melbourne, Sydney, Brisbane networks the two frequencies are
independent operating over two carrier or bearer links. The diagram
below shows a typical Adelaide and Canberra configuration.
Note the audio is combined as a single 600 ohm
-10dbm output.
The
satellite system instead, simply provides a data stream in a digital
format which can be easily transported through traditional serial
transmission based bearer services. In this case a 9600 baud
asynchronous data stream over a satellite service.
The E2000 has kept all of its normal TNPP packet
processing, batching, monitoring and message queuing. The FSK continues
to request the network and the Encoder formats the POCSAG data as
described previously. The reason for this is the satellite operates on
two frequencies and the E2000 must content for these two subsystems.
Sydney 2010 full production design
The production system installed in 2010 is a
standard E2000 configured as a PPE in a switching network configuration.
The only difference is the replacement of the E2004 by the E2005 Encoder
card and the removal of the E2019 FSK card. The new E2005 design handles
the network handshake which the E2019 was providing in the prototype.
The production system will allow the PPE to run priority ports again on
the input to the system thereby retaining the original PPE priority port
design.
The data is sent to the network connector on the
E2052 as normal however instead of the analogue modem output pins there
is a separate RS232 data pins. Jumpers J1301 and J1304 are selected to
apply the RS232 signals to the connector.
Network Output
The satellite data appears as RS232 data on the
Network Output connectors. The feed into both Network Output 1 and
Network Output 2 is the same so either socket can be used.
RS232 Data is on pin 3 of the RJ12 connector
RS232 Ground is on pin 2 of the RJ12 connector
Front Panel
The satellite system has 2 cards plus the power
supply. The Encoder is the new E2005 which replaces the E2004. The main
processor is the normal E2050.
The diagram below is a mimic of the front panel.
On the Encoder the three LEDS are
-
CTS This indicates the system has been given the clear to transmit from
the contention processor on the E2052 on the back plane.
-
RTS
This is raised from the Encoder when the E2050 Processor has data to
transmit and has requested the Encoder to acquire the network.
-
Data This LED is the asynchronous data being pumped out the serial port
to the E2052 backplane.
On the Power Supply the three LEDS are
-
AC-DC
This is the AC to DC converter. It produces the standard 13.8 volts
-
Common
This is the power common to both systems. Both power supplies feed
into this power rail. Common LED will be lit whenever one supply is
connected and switched on by the internal switch on the card.
-
On-Line
This LED indicates the AC-DC is switched to the common rail and is
therefore on line. Turning off the card switch will extinguish the
LED.
On the Main Processor there are 6 six sets
of LEDS each set is a serial port on the processor. Green is the
transmission from the processor, red is receive. The 6 ports are
-
Monitor Port
This is the data to and from the PPEViewer program. Note the
transmit LED will flash even if the PPEViewer is not connected.
-
Port B TNPP
This is the main input for TNPP packets and is Port B on the E2052.
This will flash when paging data is sent to the system.
-
Bus Port C
This is the bus between the Encoder and the Main Processor. It runs
at 38.4kBits/second. This flashes constantly.
-
Port D TNPP
This is the dedicated TNPP packet priority input. Any packet sent to
this port has priority over all other packets. This port appears on
the rear back plane.
-
Port E Intersys
This port is the receive from the other system. Paging packets are
received from the other system, for this system. It is also used to
send inter-system messages. This port appears on the rear back
plane.
-
Port F Intersys
This port is the opposite to port E. This port appears on the rear
back plane. Port E and F are interconnected on the rear E2052 panel
with crossover cables.
Satellite asynchronous serial protocol
The satellite data is structured and delivered on a
time based packet in sync with the normal Encoder bus processing. i.e.
32 bits of data are delivered in 4 bytes in sync with the real POCSAG
transmission. In this way the broadcast data stream is delivered over
the satellite without burdening the remote site decoder with too much
buffering.
The data stream
is also modified to provide a header which gives the remote site
information on which frequency and baud rate the data stream is to be
retransmitted.
The format
of the data stream for the Sydney October design is shown below.
In the production design the 700mSecond gap is
reduced to a period dependent of the bit rate. This is because there is no transmission key-up
overhead from the PURC control cards as in the prototype design.
