VSG60A Windows C API

Hello all,

I have a couple of questions regarding the Windows DLL API for the VSG60A. I’m using the latest version of the API (2020-01-06).

The vsgOutputWaveform, vsgRepeatWaveform, and vsgSubmitIQ functions all take input buffers of type ‘float *’. Is there some reason why this is not ‘const float *’? I’m assuming this is a small oversight and I can just pass in a (casted) buffer of const data, but I wanted to be sure. I can’t imagine why the implementation would need to modify the input buffer.

It looks like whenever I turn off RF output (via vsgSetRFOutputState), I can never get any output (using vsgRepeatWaveform or vsgOutputCW) when I turn it back on. The only way for me to get output again is to close the handle and establish a new connection. It’s as if the function can only turn off RF output and not turn it on. I understand that I can stop output via vsgAbort, but I liked the idea of completely gating RF output with that switch independently of current playback.

Any feedback would be greatly appreciated. Thanks for your time.

Mike.

[Andrew]

Hi Mike,

You are correct about the float* parameter. It should be const, and the data is not modified by the API. I will see about getting this in a future update. Yes, you are safe to cast.

I can’t reproduce the issue you are seeing regarding RF output on/off. I wrote a short script to attempt to reproduce. Maybe you could try to run this? If all else fails, maybe you could whip up a simple script I could try to run and reproduce? See code below.

This function simply turns on and off the RF output in 1 second intervals. I observed the power going on and off at these intervals.

void testRFOutput()
{
    int handle = -1;
    VsgStatus vsgSts = vsgOpenDevice(&handle);
    if(vsgSts != vsgNoError) {
        printf("Unable to open VSG\n");
        return;
    } 

    vsgSetFrequency(handle, 1.0e9);
    vsgSetLevel(handle, -40.0);

    while(true) {
        vsgSetRFOutputState(handle, vsgTrue);
        vsgOutputCW(handle);
        Sleep(1000);
        vsgSetRFOutputState(handle, vsgFalse);
        Sleep(1000);
    }
}

Look forward to your response.

Regards,
Andrew

• This reply was modified 5 years, 2 months ago by Andrew.

Hello Andrew,

Thank you for your quick reply. I can confirm that your sample code is running just fine, thank you. I modified your sample code to do what I was trying to do. In the code below, I see the output for a second and then never again.

void testRFOutput()
{
    int handle = -1;
    VsgStatus vsgSts = vsgOpenDevice(&handle);
    if(vsgSts != vsgNoError) {
        printf("Unable to open VSG\n");
        return;
    }

    vsgSetFrequency(handle, 1.0e9);
    vsgSetLevel(handle, -40.0);

    vsgSetRFOutputState(handle, vsgTrue);
    vsgOutputCW(handle);

    while(true) {
        Sleep(1000);
        vsgSetRFOutputState(handle, vsgFalse);
        Sleep(1000);
        vsgSetRFOutputState(handle, vsgTrue);
    }
}

I thought that the vsgSetRFOutputState was a function I could use to quickly gate the output without having to generate a new waveform, which could potentially be an expensive operation. At any rate, I think I have everything I need so thank you for the help!

Regards,
Mike.

Thanks for the follow up. I see how that could be confusing. Let me know if I can help with anything else.

[Author]

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