SME Digital Modulation
1038.6002.02 2.91 E-13
2.6.3.7 QPSK Modulation
Menu DIGITAL MOD - QPSK offers access to settings for QPSK modulation setting range of the bit
rate is 1.00 to 24.3 kbps and 27.0 to 48.6 kbps. In range 1.00 to 24.3 kbps the nonharmonic
suppression is reduced by aliasing products. The spurious products occur at the frequency spacing =
15
×
bit rate. The spurious level is shown in the diagram.
Spurios products [dBc]
-40
-50
-60
-70
-80
0 10 20 30 40 50
Bit rate [kps]
Menu selection DIGITAL MOD - QPSK
FREQUENCY
LEVEL
MODULATION
DIGITAL MOD
LF OUTPUT
SWEEP
LIST
MEM SEQ
UTILITIES
HELP
GMSK
GFSK
QPSK
FSK
4FSK
FFSK
FREQ
100. 000 000 0
MHz
L
E
V
EL
dBm
SOURCE
OFF EXT PRBS DATA
PRBS 9 15 20 21 23 Bit
CLOCK... POS / COUPLED / SYMBOL
LEVEL ATTENUATION MODE OFF NORM MAX
LEVEL ATTENUATION 0.0 dB
MODE AUTO SINGLE
SELECT STANDARD... CURRENT: NADC
MOD TYPE
π
/4DQPSK
BIT RATE 48.6k bps
FILTER...
√
COSINE/0.35
CODING... NADC
MOD POLARITY NORM INV
SELECT LIST... CURRENT: DLIST3
DELETE LIST...
FUNCTION FIIL INSERT DELETE EDIT/VIEV
CONFIG XMEM...
- 30.0
Fig. 2-43 Menu DIGITAL MOD - QPSK (preset setting), fitted with option SME-B11, DM coder
SOURCE
Selection of the modulation source for QPSK.
IEC-bus command :SOUR:DM:TYPE QPSK; SOUR EXT; STAT ON
PRBS
Selection of the Pseudo Random Binary Sequence.
IEC-bus command :SOUR:DM:PRBS 9
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