GENERAL INFORMATION
1-11
Amplitude modulation
For carrier frequencies up to
1 GHz:
Range
0 to 99.9%.
Selection
By keyboard entry of data. Variation by
Ø
/
×
keys and by rotary
control.
Resolution 0.1%
Indication
3 digits with annunciator.
Depth accuracy at 1 kHz
±
4% of setting
±
1%.
External AM 1 dB bandwidth
With modulation ALC off; DC to 30 kHz in DC coupled mode and
10 Hz to 30 kHz in AC coupled mode. Typical modulation bandwidth
exceeds 50 kHz.
Distortion
For a modulation rate of 1 kHz:
Less than 1% total harmonic distortion for AM depths up to 30%;
Less than 3% total harmonic distortion for AM depths up to 80%.
Modulation source
Internal LF generator or external via front panel connectors.
Digital modulation
In digital mode the instrument can be used over the carrier frequency
range 10 MHz to 2.7 GHz (to 1.35 GHz for 2050T) and accepts
internal or external data to modulate the RF output. The modulation
can be applied in common digital formats and the channel filter
characteristics specified.
Internal data
All '0's, '1's or selectable PN 2 to 7, 9 to 11 or 15 PRBS sequence.
Note that in GSM mode, PRBS is limited to PN9 or 15. All 0’s and 1’s
are available.
External data
Accepts data as a serial or parallel input from a 25-way AUXILIARY
D-type connector on the rear panel. Accepts symbols containing 1 to
8 data bits with internally or externally generated clock sources. In
GSM mode external input must be supplied as 8-bit parallel data.
All inputs and outputs are TTL/CMOS logic compatible.
Symbol rate
Modulation type
Filter type
Symbol rate (sym/s)
PSK / QAM
Nyquist / Root Nyquist
1900–34000
PSK / QAM
Gaussian
1900–25000
FSK / GMSK
Gaussian
512–25000
FSK
Nyquist / Root Nyquist
1900–25000
OQPSK All
filters 1900–16000
Symbol source can be internal or external (on rear panel connector).
Internal symbol rate is adjustable in 0.1 symbol/s steps.
Symbol rate must be within 2% of the external symbol rate to
maintain modulation accuracy.
Generic modulation types
Can select PSK, differential PSK, differential phase offset PSK
(
π
/4 DQPSK), time-offset QPSK, QAM, GMSK and FSK.
Number of bits per symbol can be selected from 1 to 3 for PSK
systems, 2 to 8 for QAM systems and 1 or 2 for FSK systems.
RF channel filters
Root raised cosine, raised cosine or Gaussian.
Filter bandwidth can be selected as follows:
Raised cosine or root raised cosine for
α
from 0.2 to 0.8 in 0.01
steps.
Gaussian 3 dB bandwidth from 0.4 of symbol rate (0.2 of symbol rate
as IQ baseband filter) up to a maximum of 22.6 kHz.