modification of frequency sweep.vi

[kwanghyun92]

Hello.

I am trying to measure frequency sweep data using function generator(agilent 33250A) and oscilloscope(DSO-X-4024A).

But I have some difficulties making frequency sweep when I use "configure frequency sweep.vi".

The difficulty is that frequency sweep is repeated automatically until I will stop the program.

Before describing my problem, Let me explain "configure frequency sweep.vi".

I should give some data to "configure frequency sweep.vi", 'start frequency', 'stop frequency', 'sweep time', to use this vi.

For example, If I start the "configure frequency sweep.vi" with 3700Hz(start frequency), 3800Hz(stop frequency), 100s(sweep time), the program will be repeated automatically after the frequency reach the stop frequency.

Let me describing my problem.

I want to make the frequency signal will be held when the frequency sweep reach a stop frequency that I set.

For example, If the frequency reaches the stop frequency(3800Hz), the function generator will emit the signals(3800Hz) until I stop. 

I want to discuss this problem with you.

I attach a block diagram of "configure frequency sweep.vi". 

[jamiva]

This is from the manual. It looks like you need an external trigger to do what you want.

[kwanghyun92]

Thanks for your replying.

I knew the fact.

but the external trigger provides only 1 time frequency sweep and output will be not held after 1 time frequency sweep.

[jamiva]

I don't have an Agilent 33250A. Quickly looking at the manual, I think you have a hardware limitation with that SigGen model.

I do have a slightly newer model (Agilent 33521A) and it has two additional sweep parameters: "hold time" and "return time". I was able to easily create your waveform. Probably time to either redefine your test waveform, or find other hardware that meets your needs.

[jamiva]

I was thinking that you may have another option:

It looks like you want to scan from 3700Hz to 3800Hz over a 100 sec sweep time. That's a 100 Hz delta over 100 seconds, or a sweep rate of 1 Hz/sec

You could programmatically create a loop to update the frequency by 1 Hz every 1 sec. That is if you can live with the discontinuities of a stepped sine wave. Also, the hardware will not switch frequencies at exactly 1 sec intervals. It take a finite amount of time to send the command, process the command, and for the waveform to settle. However, the advantage of doing it this way is that you could synchronize/trigger the o'scope to capture a CW waveform during that 1 second interval.

[kwanghyun92]

After reading your replying, I check the manual of Agilent 33250A.

Unfortunately, this model doesn't have the function("hold time" and return time".)

[kwanghyun92]

Actually, I made the program as you said above(prgrammatically repeat a loop to update the frequency by 1 Hz every 1 sec.

But, I want to make the frequency increase with continuously data.

I mean that there will be so many data between 3700Hz and 3701Hz.

(3700Hz, 3700.0001Hz....3700.9999Hz)

But the program that create a loop to update the frequency creates only point of signal.

(3700Hz, 3701Hz)

So I am trying to make a program using "configure frequency sweep.vi".