Hi. My name is Jim and in this video I’m going to demonstrate some of the triggering
and gating capabilities of Agilent 53230A counter as they apply to time interval measurements.
If we take a look at the oscilloscope, you can see that currently we are measuring a
500 kHz square wave with a period of 2 micro seconds. If you look back at the counter,
you can see that we are also making that frequency measurement of 500 kHz. We can also make a
period measurement of that same signal by pressing the period softkey, and as you can
see, we have a much more accurate measurement using the counter, of the period of the input
signal. For the purposes of this demo, what we want to do is make a period measurement
in terms of a time interval measurement and emphasize the triggering and gating capabilities
of the counter to accurately make the measurement. The first thing we’re going to do is begin
by configuring the counter for a time interval measurement. We do that by first presetting
the instrument. Then after the preset is complete, we’ll go ahead and select the time interval
function using the time interval key. Followed by the time interval softkey. The time interval
channel selection. In this case we will select 1-1 because we want to make a single channel
time interval measurement. Once that is set, we want to look at the stop conditions on
the stop channel, which again is the same channel. You’ll notice that the stop slope
in this case has been set to negative due to the instrument preset. If we pan back over
and look at the scope, what this current condition will give us now is we will start a measurement
beginning on the rising edge, and stop on the negative, or falling edge. Which will
only give us measurement of half the period. We are interested in measuring the full period
or the time interval of one period of the input signal. To do that, going back to the
counter, I’m going to change the stop slop from negative to positive. Once my measurement
is set up, I can then go ahead and set my triggering and gating parameters. Triggering
– I will go ahead and press the trigger key. I will set the trigger source to manual.
This will suspend triggering until I issue a manual trigger by pressing the trigger key
again. To set up my gating parameters, I select the gate key. I will set my gate source to
advanced. In this case I’ll be interested in the stop menu. Note in the stop menu that
I have a gate hold-off of none. That means that the gate will go ahead and close once
the conditions of the input signal have been satisfied in order to close the gate. If I
go ahead and make a measurement now, you’ll see the impact of not holding off the gate
close. I’ll press trigger to make a single measurement. And as you can see, we’re making
a measurement that is much much shorter than the period of the input signal. Looking back
over at the oscilloscope, what we’re seeing is because the conditions and not having a
gate hold-off, we are both opening and closing the gate and making the measurement on the
same rising edge of the input signal. What we want to do is to be able to delay the gate
closing using a gate hold-off until we pick up the next rising edge of the signal. Therefore,
giving us a period measurement. To do that, I will go back and using the gate key and
the stop menu softkey, I will set a hold-off source to expressing it in terms of time.
I will go ahead and accept a 1 microsecond default time as a gate hold-off. Pressing
trigger again – and there is my accurate and correct measurement of 2 microseconds.
Again, if we pan back over to the scope, what we have done by setting the gate hold-off,
is we’ve prevented the gate from closing until the conditions of the close, which are
the positive edge have been satisfied. Those occurring on the next rising edge – therefore
giving us a measurement of the single period.