User's Manual

COMPANY CONFIDENTIAL
RF-TWACS Based AMR System DCSI CUSTOMER PRODUCT SPECIFICATION
May 30, 2003 Application Notes – Rev. 1 9
As can be seen, EMTRs never request a link; they are always acceptor transceivers. By
contrast, RMTRs never grant a link; they are always requestor transceivers. The HHTR,
since it must be able to communicate with both EMTRs and RMTRs, can act as either an
acceptor transceiver (with an RMTR) or a requestor transceiver (with an EMTR).
The reason this distinction is important is that the acceptor transceiver always controls
the channels hop sequence. This means that an EMTR always controls the hop sequence.
An HHTR controls the sequence when communicating with an RMTR. An RMTR never
controls the hop sequence.
Bear in mind that this distinction between acceptor and requestor transceivers is strictly
operational. It is not a functional difference because the same RF transceiver and RF
engine code are used on all transceivers.
The RMTR is a battery powered device. In order to maximize battery life, the RMTR is
powered off as much as possible. The requirement to maximize battery life drives a
number of other factors in the system. One implication of this is that the normal
Master/Slave relationship, evident throughout the design, which begins at the CCE, now
ends at the EMTR. The EMTR cannot wake up the RMTR to establish a session, but can
take control of a session once it is established by the RMTR.
The RMTR is designed to wake up once an hour and create a session with an EMTR.
Any unknown data is uploaded at that time from the RMTR to the EMTR. At any given
time, the EMTR knows nearly everything the RMTR knows, plus it maintains
engineering data to describe the quality of the radio link. The CCE may access this data
upon demand.
The EMTR maintains an “acquisition list” table. Each RMTR is categorized as belonging
to a certain type of service. The various types are: Electric, Water, Gas, and Propane. A
number of ports are supported for each service type. The CCE reads data from the
appropriate port in order to obtain information.
4.2 RF Hardware Specifications, Installation, Operations & Maintenance
4.2.1 Centron Meter
In addition to supporting TWACS communication, the EMT-3C-MP module hosts the
LCD and the metering components from Schlumberger. The EMA also supports the
connection to the EMTR board which is housed under the same canopy, this is shown in
Figure 7. Figure 8 shows the EMT-3C-MP transponder integrated with an Schlumberger
solid state Centron electric meter.