Delayed Voltage and Delayed RMS Power are functions that allow the receiver to make measurements precisely in time relative to a trigger point. In addition this allows profiling of repetitive RF phenomena using an undersampling technique. In Receiver Revision 7322I and above the Delayed Voltage measurement is available and in Revision 7322J and above receivers, both the Delayed Voltage and the Delayed RMS Power are available.
In this case the receiver is making 101 measurements, 1 per each of 101 pulses, all pulses 10uSec in width, With the measurement occurring between 2 and 9 uSec after each trigger event. ** Note: The last item in the pre-measure is a sequence delay. This sequence delay must be set to be slightly longer than the longest delay, enabling the receiver to finish its measurement before the test panel captures it.
In the following case we want to measure the rise time of a power amplifier by synchronizing the Delayed Voltage measurement to the power amp's enable pin (driven from Db 13). The receiver is again making 101 measurements, 1 per each repetition of 101 enables. With the measurement occurring between 0 and 20 uSec after each trigger event. ** Note: The last item in the pre-measure is again a sequence delay. This sequence delay must be set to be slightly longer than the longest delay, enabling the receiver to finish its measurement before the test panel captures it.
Example 2 results
This measurement yields the following graph from which we can determine Rise Time as well as determine if any overshoot or ringing may occur:
Note that, when measuring absolute delays, the tester may have internal delays as much as +/-3 us. These internal delays will vary, depending on the items in the test panel. However, they are consistent from tester-tester, and therefore can be mathematically removed.