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Chapter 7. Typical Applications
7.1 Application Notes on Applying Hybrids:
•
All
Ametek/Pulsar
systems are designed to have their TX &
RX bridged directly together in 2-wire
mode without hybrids. (See Figures 7–4 &
7–5)
•
A Balanced Hybrid should always be used if
combining 2 Transmitters. Never use a
Skewed hybrid for this application. (See
Fig. 7-1)
•
A Skewed Hybrid will give 3 dB less TX
loss and thus a 3 dB improvement in signal
to noise ratio so it is the recommended
hybrid for combining a FSK carrier set TX
& RX together. (See Fig. 7-2)
•
Hybrids should be arranged with the lesser
losses in the transmitter path and the greater
losses in the receiver path to provide more
transmitter signal levels onto the power
line.
•
ON/OFF DCB Carrier systems should be
arranged with less losses than FSK systems
when combining together with hybrids
where possible, as they need higher
signal/noise ratios than FSK systems. (See
Fig. 7-5)
ON/OFF
Carrier
Copyright © AMETEK Power Instruments
•
If possible transmitters used for common
applications should be arranged for equal
attenuation. For example, it is ideal to have
Dual channel DTT Transmitters combined
through the same balanced hybrid. (See Fig.
7-3)
•
If required, to split signals instead of
combining, a balance transformer is used.
The balance transformer is equal to a
balanced hybrid in reverse. This is done to
split signals for phase-to-phase coupling to
two different phases of the power-line. (See
Fig 7-6)
•
For redundancy, where no single point of
failure is allowed in a phase-to-phase
coupled system, a balanced combiner
hybrid arrangement can be used where 4
balanced hybrids are interconnected. If any
one hybrid fails, at least one of the systems
(Primary or Backup) continues to work .
(See Fig. 7-7)
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