A2538-003/01 March 2020
SEMCO Proprietary Information
28
3.2.5 Using an External Data Source
Touching the
Modulation Data Source
window and
External
(Figure 3-34) allows the user to provide
either an external TTL modulation input via the Data Input BNC or DB Input I/O. Table 3-1 provides the
external signal input characteristics per modulation format. Table 3-2 provides information regarding
minimum and maximum external input signal levels.
Figure 3-34
External Modulation Data Source Selection
Table 3-1
External Modulation Source Requirements
Mode
I IN
Q IN
PCM/FM
TTL Data
Not Used
BPSK
TTL Data
Not Used
QPSK
TTL Data
TTL Data
SOQPSK, CPM
TTL Data*
TTL Clock
*Data is latched on falling edge of Digital Clock.
Table 3-2
External Modulation TTL Signal Level and Impedance
Input Logic
Minimum Signal Level
Maximum Signal Level
Impedance
VIH
1.7 V
75 ohms
VOH
0.7 V
75 ohms
3.2.6 Bit Synchronizer Control Panel
Figure 3-35 depicts the Bit Synchronizer (
Bit Sync
) Control Panel, which provides a green
Lock
or
Unlock
status display,
Decoder Code
and
Encoder Code
selection,
Encoder Data Polarity
,
PN
Data Pattern (Gen Pattern)
selection,
De-Randomizer
ON/OFF
,
Loop Bandwidth (Loop BW)
selection and
HI/LO Input Impedance
(
Input Z
) selection. Each of these controls are briefly described
in the following paragraphs.