Unclassified
Installation Procedure
3-5
3.8 INSTALLATION PROCEDURE – RADIO WITH PPS OPTION
3.8.1 PPS FUNCTIONS
The optional Preselector/Postselector, PPS-100 (referred to as PPS in this manual),
permits operation of collocated receivers and transmitters on frequencies separated by as
little as 10%. The PPS operating frequency range is 1.60 to 29.99 MHz. To use the PPS,
order the RM500/RM500R with option G65. The connections between an
RM500/RM500R with option G65 and the PPS are shown in Figure 5.
When the G65 option is installed, the PPS is controlled by the RM500/RM500R through a
serial port, and is automatically inserted by the RM500/RM500R in the signal path in
accordance with the operating mode:
In the receive mode, the PPS functions as a preselector, providing an additional front
end selectivity stage for the receive path of the RM500/RM500R. This reduces the
receiver desensitization and overload that would normally occur in the presence of
strong adjacent RF transmissions.
In the transmit mode, the PPS is used as a post selector. It attenuates spurious signals
and broadband noise in the driver transmit signal before it reaches the internal 500W
power amplifier, thereby reducing interference to neighbouring receivers.
In both modes, the PPS automatically tracks the RM500/RM500R operating frequency.
Rapid tuning makes the PPS suitable for Automatic Link Establishment (ALE) or
Adaptive Applications.
During self-test, the PPS automatically switches to the bypass mode: in this mode, RF
signals pass directly through the PPS, without filtering, and therefore the PPS does not
interfere with system operation. The PPS also switches to the bypass mode when the
RM500/RM500R frequency is outside the PPS operating range, 1.60 to 29.99 MHz.
In case excessive RF power is applied to the PPS, the PPS enters the RF overload
protection mode: in this mode, the PPS antenna port is disconnected, and the internal
antenna input is short-circuited to ground. This also protects the RM500/RM500R internal
transceiver against overload.
The PPS is housed in a 1U high (1.75 in.) case intended for 19 in. rack mounting.
Standard operation is from 115/230 VAC, 50/60 Hz, and can also be powered from 12 or
24 VDC DC sources.
3.8.1.1 PPS Installation Procedure
NOTE
The following procedure assumes that the basic
RM500/RM500R unit has already been installed, as
previously explained (page 16).
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