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: 6-4
Copyright © 1997 Glenayre
Print Date: 02/19/97
6.2.2.3
Channel-Select-Bit Strapping
The MCU control circuit reads three bits to determine the remotely selected channel. If the
controller provides only bits 1 and 2 (CH SEL 1, 2), the controller can command only four
channels. The operation of bit 3 is a function of the controller interface. Refer to Section 10.
controller provides only bits 1 and 2 (CH SEL 1, 2), the controller can command only four
channels. The operation of bit 3 is a function of the controller interface. Refer to Section 10.
6.2.2.4
Mode-Select-Bit Strapping
The MCU control circuit reads two bits to determine the remotely selected mode. If the
controller provides only bit 1 (MODE CONTROL), the controller can command only two
transmitter modes. The operation of bit 2 is a function of the controller interface. Refer to
Section 10. If the controller interface does not use bit 2, it straps it to ground (low).
controller provides only bit 1 (MODE CONTROL), the controller can command only two
transmitter modes. The operation of bit 2 is a function of the controller interface. Refer to
Section 10. If the controller interface does not use bit 2, it straps it to ground (low).
6.2.2.5
Power Sample D/A Conversion
The controller reads sample voltages for its forward and reflected power sample inputs,
which are stored as data in the MCU control circuit. In some cases the controller interface
converts the data to voltages of the appropriate range for the controller. Data from the MCU
representing the forward and reflected powers is written into a dual D/A converter, which
converts the data into two proportional dc voltages, which are applied to the controller.
Control logic gates ensure that data is written to the proper half of the D/A converter.
which are stored as data in the MCU control circuit. In some cases the controller interface
converts the data to voltages of the appropriate range for the controller. Data from the MCU
representing the forward and reflected powers is written into a dual D/A converter, which
converts the data into two proportional dc voltages, which are applied to the controller.
Control logic gates ensure that data is written to the proper half of the D/A converter.
6.3
DSP Modulator
6.3.1
General
The DSP modulator circuit converts the data into the first IF signal, which is fully modu-
lated. The IF stage circuit converts the first IF signal into the second IF signal. The RF stage
circuit converts the second IF signal into the RF output. Ten MHz is used as frequency
reference by each conversion stage. The DSP modulator is the portion of exciter circuitry
between the controller interface and the IF stage. The DSP modulator uses digital signal
processing to modulate and up-convert the paging information into the first IF signal. The
modulation type depends on the transmitter operating mode. The IF stage is the portion of
exciter circuitry between the DSP modulator and the RF stage. The IF stage uses hetero-
dyne mixing to generate the optimum second IF signal frequency, which depends on the
requirement of the VCO/RF amplifier board installed. The MCU control circuit is the
command and control hub of the transmitter. The type of control software depends on the
transmitter frequency and power output. The following text describes main exciter circuitry
that works for all software programs, modulation schemes, and IF signal frequencies.
lated. The IF stage circuit converts the first IF signal into the second IF signal. The RF stage
circuit converts the second IF signal into the RF output. Ten MHz is used as frequency
reference by each conversion stage. The DSP modulator is the portion of exciter circuitry
between the controller interface and the IF stage. The DSP modulator uses digital signal
processing to modulate and up-convert the paging information into the first IF signal. The
modulation type depends on the transmitter operating mode. The IF stage is the portion of
exciter circuitry between the DSP modulator and the RF stage. The IF stage uses hetero-
dyne mixing to generate the optimum second IF signal frequency, which depends on the
requirement of the VCO/RF amplifier board installed. The MCU control circuit is the
command and control hub of the transmitter. The type of control software depends on the
transmitter frequency and power output. The following text describes main exciter circuitry
that works for all software programs, modulation schemes, and IF signal frequencies.
6.3.2
DSP Modulator Signal Flow
, in the following
discussion. The inputs that provide the paging information to the DSP modulator circuit are
digitized audio and FSK data, supplied by the controller interface circuit through connector
pair P1/J1. Digitized audio arrives as serial data. FSK data arrives as parallel data. The DSP
modulator circuit processes the digitized audio in the analog mode or the FSK data in the
digital mode. The result of this processing is the exciter’s first IF signal, which is applied
digitized audio and FSK data, supplied by the controller interface circuit through connector
pair P1/J1. Digitized audio arrives as serial data. FSK data arrives as parallel data. The DSP
modulator circuit processes the digitized audio in the analog mode or the FSK data in the
digital mode. The result of this processing is the exciter’s first IF signal, which is applied