SME Digital Modulation
1038.6002.02 2.79 E-13
2.6.3.1 Data Generator
The data generator contains a memory for the data (DATA), for level switchover (LEV ATT) and for the
BURST output (BURST) each. The data generator can be programmed via the IEC bus or manually
using the list editor (cf. Fig. 2-37). The maximal memory capacity is 8192 bits. The data generator can
also be programmed for shorter sequences. The data of all three memories are combined in a list. Up
to 10 different lists can be stored in the instrument.
Option SME-B12, DM memory extension, increases the memory depth to 8 MBit (cf. Section 2.6.3.3,
DM memory extension, option SME-B12).
The DATA memory contains the modulation data bits.
The LEV-ATT memory contains the bits to control the level reduction. A logic "0" means the level
indicated in the header field. A logic "1" means a level reduction by the value indicated in the menu
under LEVEL ATTENUATION. For a constant carrier, either the bits of the LEV-ATT list or the
parameter LEVEL ATTENUATION must be set to 0.
The BURST memory contains the bits to control the BURST output. A logic "1" means level HIGH. A
logic "0" means level LOW.
What is to be observed is that the modulation generation is subject to a delay that must not be
neglected. In order to keep the level reduction or the BURST signal synchronous with the modulation,
these memories are to be programmed offset by the delay. The delays of the different modulations are
listed in table 2-5, radio network data (cf. Fig. 2-38, signal example with respect to DM delay as well).
Sockets DATA, CLOCK and BURST are switched to be an output if the data generator is switched on,
and the bit sequences can be tapped there. The BURST output can be used to control the pulse
modulator or to trigger the LIST mode, if there is an external cable connection from the PULSE input or
TRIGGER input at the rear of the unit.
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
SELECT LIST... CURRENT:DLIST1
FUNCTION FILL INSERT DELETE EDIT/VIEW
-NR- FREE 6942- LEN 1250 DATA LEV ATT BURST
0001 00100011 11100000 00011111
0009 01110110 00000000 11111111
0017 00110101 00000000 11111111
0025 11010010 00000000 11111111
0033 11010010 00000000 11111111
0041 11010010 00000000 11111111
0049 11010010 00000000 11111111
0057 11010010 00000000 11111111
LEVEL dBm
GMSK
- 30.0
Fig. 2-37 Menu DIGITAL MOD-GMSK, edit page
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