custom waveform

[Clint Eastwood]

Does LV8 have anyway of generating a custom waveform??  A guess it would be TTL.

I'm trying to generate a custom bit pattern.

The specs are:

A Logic 1 is 2 microsecs long with an amp of +5 vdc.  The rise & fall times ( which are critical!!) is no more than 0.6 microsecs.

A Logic 0 is 2 microsecs long with an amp of -5 vdc.  The rise & fall times ( which are critical!!) is no more than 0.6 microsecs.

Between a logic 1 and a logic 0 is about 2 microsecs.

Can you do this with an array of values?? Multiplying two waveforms together??  Is there  a shipping example just like this/

Thanks,

Clint

[johnsold]

Clint,

LabVIEW can specify the timing, but as software, it cannot generate the voltages. The voltages you list are NOT TTL! Nor are they any standard logic family that I have heard of.

Your specification is unclear on one point: You specify rise and fall times of 0.6 us and a time between logic 1 and logic 0 of 2 us. This seems inconsistent. What is the signal doing for the 1.4 us difference?

If your signal must swing from +5 V to -5 V in 0.6 us, then you will need an amplifier with a slew rate > 16.6 V/us. This is fast but many such amplifiers exist. How much current is required statically and dynamically?

Lynn

[Clint Eastwood]

Lynn,

I'm using a DAQ Card to actually generate the signal ( PXI 6259).

I would just like a VI that allows me to vary a signal's rise and fall times as well as make the signal bipolar.  I also think I may need to have control over the duty cycle.  I'm thinking this because I want to vary the time between the logic 1 occurance and a logic 0 or another logic 1.

Clint

[Sappster]

Hi Clint,

Your board supports what you want to do. you have a slew rate of 20V/us which will accomplish the 10V swing in .5us. As far as changing the rise/fall time, I don't believe you can control that unless you build it into your signal. For example, if instead of writing 0V then +5V (rise time = .25us) you can write 0V then 2.5V then 5V at the same sampling rate to double your rise time. As for the rest of it, I suggest you create your signal in an array and write it with hardware timing.

Mark