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Frequency of Multiple
Segment Waveforms
Setting the Output
Attenuation
Format
Appendix C
When two or four waveform segments make up the output waveform, the
waveform repetition frequency is 1/2 or 1/4 of the programmed frequency.
For example, if the RAM size is 8k, the waveforms in RAM 1 and RAM 2
comprise the output waveform. If the programmed frequency is 1 kHz, the
output frequency is 500 Hz. Similarly, if the RAM size is 16k, the
waveforms in RAM 0 through RAM 3 make up the output waveform. If the
programmed frequency is 1 kHz, the output frequency is 250 Hz. For 1 kHz,
you must either double or quadruple the programmed frequency.
The maximum output voltage is +5.1175V / -5.12V into 50 .
The amplitude is controlled by the 12-bit output attenuator. The attenuation
value written to the AFG is based on the desired amplitude (volts peak) and
the output load:
Amplitude > + 0.51175 into 50 :
Atten = (Ampl / 5.1175) * 2047
Amplitude < + 0.51175 into 50 :
Atten = (Ampl / 0.51175) * 2047
Amplitude > + 1.0235 into open circuit:
Atten = (Ampl / 10.235) * 2047
Amplitude < + 1.0235 into open circuit:
Atten = (Ampl / 1.0235) * 2047
Atten is the attenuation value set from the Parameter Register and
the desired output amplitude in volts peak.
The attenuation is a two-byte parameter whose bits are defined in Table
C-2. The attenuation value
8
A
*2
+A
1
2
As an example, to set 2 V
Atten = (2 / 5.1175) * 2047
= 03
20
16
= 3
32
+ 128
10
= 131
32
10
byte 1 byte 2
128 is added to set bit 7, which turns the 20 dB attenuator off.
HP E1340A Register-Based Programming 245
(no attenuation)
(20 dB attenuation)
(no attenuation)
(20 dB attenuation)
is converted to the form:
(Atten)
into 50 :
pk
Ampl
is
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