Glenayre Electronics Inc. GL-T8600-CN Manual Do Utilizador
DSP Exciter
Glenayre Document Number: 9110.00172
THEORY OF OPERATION
Issue 1, Rev. I: 01/15/97
Page: 6-14
Copyright © 1997 Glenayre
Print Date: 02/19/97
6.5.5
VSWR-Fault Detector
The exciter receives a VSWR signal from the PA through connector J7. This signal is a
rectified dc voltage sample generated by the isolator. The voltage sample is monitored by
the MCU to provide the value for the total reflected-power indication. The voltage sample
is also monitored by a fault circuit in the exciter. If a factory-preset voltage is exceeded, the
fault circuit shuts down the transmitter by an interrupt to the MCU.
rectified dc voltage sample generated by the isolator. The voltage sample is monitored by
the MCU to provide the value for the total reflected-power indication. The voltage sample
is also monitored by a fault circuit in the exciter. If a factory-preset voltage is exceeded, the
fault circuit shuts down the transmitter by an interrupt to the MCU.
6.5.6
Alarm Data-to-Logic Conversion
The transmitter controller reads logic alarm inputs; most of these alarms are stored as data
in the MCU control circuit. If the controller interface converts the data to individual logic
signals for the controller, data from MCU control representing the alarms is clocked into a
pair of latches. The latches convert the data into continuous logic signals. These signals and
others control a bank of NPN switching transistors that supply the actual logic signal to the
controller. Control logic gates convert chip controls from the MCU into a clock input for
the latches.
in the MCU control circuit. If the controller interface converts the data to individual logic
signals for the controller, data from MCU control representing the alarms is clocked into a
pair of latches. The latches convert the data into continuous logic signals. These signals and
others control a bank of NPN switching transistors that supply the actual logic signal to the
controller. Control logic gates convert chip controls from the MCU into a clock input for
the latches.
6.6
RF Assemblies
6.6.1
RF Stage Location
Refer to
, to locate the
assembly. The RF stage circuits are located on two circuit boards, both housed within the
exciter chassis.The exciter/control board is the main circuit board and the VCO/RF
amplifier board is a selected option. The exciter/control board connects to the VCO/RF
amplifier board through three connector pairs: J4/P4, J9/P9, and J10/P10. The VCO/RF
amplifier board also contains BNC connector J3, which extends through the rear panel of
the exciter. This board contains most of the RF stage components inside an RF shield. A
hole in the shield and the front panel provide access to an RF stage adjustment, which is
marked
exciter chassis.The exciter/control board is the main circuit board and the VCO/RF
amplifier board is a selected option. The exciter/control board connects to the VCO/RF
amplifier board through three connector pairs: J4/P4, J9/P9, and J10/P10. The VCO/RF
amplifier board also contains BNC connector J3, which extends through the rear panel of
the exciter. This board contains most of the RF stage components inside an RF shield. A
hole in the shield and the front panel provide access to an RF stage adjustment, which is
marked
VCO ADJ
on the front panel.
6.6.2
RF Assemblies
6.6.2.1
RF Stage Description
The RF stage is the portion of exciter circuitry between the IF stage and RF out and is the
final major functional circuit, the RF stage determines the transmitter RF output frequency,
and dictates the highest and lowest possible RF output frequencies (RF band). The trans-
mitter can be operated at several RF bands, depending on the RF stage circuitry installed in
the exciter.
final major functional circuit, the RF stage determines the transmitter RF output frequency,
and dictates the highest and lowest possible RF output frequencies (RF band). The trans-
mitter can be operated at several RF bands, depending on the RF stage circuitry installed in
the exciter.
6.6.2.2
RF Stage Bands
The selected VCO/RF amplifier board determines the RF band of the transmitter.
, lists the RF bands and the part number
of the board with that RF band.