and STOP. If the sampled signal amplitude exceeds the defined trigger level at any
single sample within the defined frequency range, the trigger will occur and the
subsequent IQ data capture will proceed.
Figure 6
illustrates the association of the time domain and the frequency domain. The
internal frequency domain data lags the time domain data by 1024 samples at the rate of
125 MSa/s. After a trigger event is detected, the subsequent time domain IQ data is then
stored to memory.
Figure 6:
Association between Time and Frequency Domain
The measurable range of the input signal, and the corresponding allowable trigger level
range, varies depending on the selected center frequency, the calibrated reference level
and the attenuation setting. When the attenuation is in the circuit (:INPut:ATTenuator
ON), the maximum trigger level to use is -10dBm; and when the attenuation is out
(:INPut:ATTenuator OFF), the maximum is -30dBm. The threshold error is approximately
-3dBm or less when the trigger level is 20dBm above the noisefloor. When the level is
within 20dBm of the noisefloor, the threshold error increases as the signal gets closer to
the noisefloor.
Note:
The threshold error is relative to the measured input signal level, which is
dependent on the calibrated reference level. The reference levels could be custom
calibrated to best fit a user's application, see the “AppNote – How to calibrate RTSA7500”
document listed on the BNC website for more information.
See TRIGger Commands section (page
69
) or SWEep's trigger (page
80
) for further
details.
Periodic Triggering
Periodic triggering provides a means of capturing a defined amount of IQ data on a
periodic basis. Periodic triggering is typically used for statistical analysis of the captured
signal.
Commands related to this feature are not available in this release.
