Digital Modulation SME
1038.6002.02 2.80 E-13
IEC-bus commands for programming the data generator::
:DM:DATA:SEL "DLIST1"
:DM:DATA:DATA 0,0,1,0,0,0,1,1,0,1,1,1,0,1,1,0
:DM:DATA:ATT 1,1,1,0,0,0,0,0,0,0,0,0,0,0,0,0
:DM:DATA:BURS 0,0,0,1,1,1,1,1,1,1,1,1,1,1,1,1
DATA
bit 1
bit 2
bit 3
bit 4
bit 5
bit 6
bit 1
bit 2
bit 3
bit 4
bit 5
bit 6
bit 1
bit 2
bit 3
bit n
delay of level
control
DM delay
(cf. table 2-5)
LEV-ATT
RF
approx. 1 µs
approx. 2µs
Fig. 2-38 Signal example with respect to DM delay and delays of level control
2.6.3.2 PRBS Generator
The PRBS generator (Pseudo Random Binary Sequence) supplies pseudo random bit sequences with
sequence lengths of
2
9
-1 = 511 ( 9 bit),
2
15
-1 = 32767 (15 bit),
2
20
-1 = 1048575 (20 bit),
2
21
-1 = 2097151 (21 bit) or
2
23
-1 = 8388607 (23 bit)
If the PRBS generator is switched on, the PRBS bit sequence replaces the data bit sequence of the
data generator. The programming of the level reduction and the BURST output remains valid even if
the PRBS generator is switched on. For a constant carrier, either the bits of the LEV-ATT list or
parameter LEVEL ATTENUATION must hence be set to 0.
Sockets DATA, CLOCK and BURST are switched to be an output if the PRBS generator is switched on,
and the bit sequences can be tapped there.
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