Glenayre Electronics Inc. GL-T8600-CN Manuel D’Utilisation
Glenayre Document Number: 9110.00172
DSP Exciter
Issue 1, Rev. I: 01/15/97
OPTIONS
Print Date: 02/19/97
Copyright © 1997 Glenayre
Page: 10-9
dsps
ec10
10.3.3 I20 Interface Conversion Functions
Many of the signals exchanged between the controller and the exciter originate with a
format, voltage, or requirement incompatible with their destination. The I20 interface
performs any signal conversions necessary to provide compatibility between the controller
and the exciter. The following text describes any signal conversions made by the controller
interface.
format, voltage, or requirement incompatible with their destination. The I20 interface
performs any signal conversions necessary to provide compatibility between the controller
and the exciter. The following text describes any signal conversions made by the controller
interface.
10.3.3.1 Analog-Mode A/D Conversion
The exciter DSP modulator circuit reads synchronized serial data for its analog mode input
signal, but the transmitter controller provides an analog signal. The controller interface
converts the analog to the appropriate data form for the DSP. The analog (FLAT AUDIO
+,-) terminates across a balanced input circuit that also provides a level adjustment. The
adjustment, when properly set by the AUDIO INPUT ADJUST pot through the exciter
cover, provides analog to an A/D converter at the optimum zero-dBm level. The A/D
converts the analog into serial data, which is applied to the DSP through a synchronous data
link. A synchronous data link is characterized by an exchange of pulse streams for timing
purposes. The A/D converter is clocked by a pulse generator circuit driven by the ten-MHz
reference circuit.
signal, but the transmitter controller provides an analog signal. The controller interface
converts the analog to the appropriate data form for the DSP. The analog (FLAT AUDIO
+,-) terminates across a balanced input circuit that also provides a level adjustment. The
adjustment, when properly set by the AUDIO INPUT ADJUST pot through the exciter
cover, provides analog to an A/D converter at the optimum zero-dBm level. The A/D
converts the analog into serial data, which is applied to the DSP through a synchronous data
link. A synchronous data link is characterized by an exchange of pulse streams for timing
purposes. The A/D converter is clocked by a pulse generator circuit driven by the ten-MHz
reference circuit.
10.3.3.2 FSK-Data-Bit Strapping
The exciter DSP modulator circuit can read up to four bits for its digital FSK mode input
signal, but the controller provides two active bits 1 and 2 (DATA1, DATA2). This allows
transmitter operation in the two-level or four-level mode.
signal, but the controller provides two active bits 1 and 2 (DATA1, DATA2). This allows
transmitter operation in the two-level or four-level mode.
10.3.3.3 Channel-Select-Bit Strapping
The exciter MCU control circuit reads three bits to determine the remotely selected
channel, and the transmitter controller provides bits 1, 2, and 3 (CH SEL 1,2,3). As a result,
the transmitter controller can command all eight of the possible channels. Table 10-3
defines the transmitter operating channel resulting from the channel select inputs.
channel, and the transmitter controller provides bits 1, 2, and 3 (CH SEL 1,2,3). As a result,
the transmitter controller can command all eight of the possible channels. Table 10-3
defines the transmitter operating channel resulting from the channel select inputs.
10.3.3.4 Mode-Select-Bit Strapping
The exciter MCU control circuit reads two bits to determine the remotely selected mode,
and the transmitter controller provides two bits (MODE SELECT 1, MODE SELECT 2).
As a result, the transmitter controller can command three of the transmitter’s four possible
modes. Table 10-4 defines the transmitter operating mode resulting from the model select
input.
and the transmitter controller provides two bits (MODE SELECT 1, MODE SELECT 2).
As a result, the transmitter controller can command three of the transmitter’s four possible
modes. Table 10-4 defines the transmitter operating mode resulting from the model select
input.
10.3.3.5 Power Sample D/A Conversion
The transmitter controller reads two 0-to-2.5-volt voltages for its forward and reflected
power sample inputs, but these power values are stored as data within the exciter’s MCU
control circuit. The controller interface converts the data to voltages of the appropriate
range for the transmitter controller. Data from the MCU representing the forward and
reflected powers is written into a dual D/A converter. The D/A converts the data into two
power sample inputs, but these power values are stored as data within the exciter’s MCU
control circuit. The controller interface converts the data to voltages of the appropriate
range for the transmitter controller. Data from the MCU representing the forward and
reflected powers is written into a dual D/A converter. The D/A converts the data into two