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1000x freq. upscaler

I asked a similar question a while ago, but received no usable replies. I'll try again, in case anyone different is looking in. Apologies to all others.

I want to generate repetitve test signals using a software frequency generator and sound card output.Theset may incorporate simple AM or FM modulation and/or an arbitray waveshape.

The problem is the upper bandwidth of the soundcard is limited to around 20KHz at best.

My idea is to use some kind of marker (short pulse, voltage threshold, etc.) to denote the desired beginning and end of the generated wave cycle. Then to have an external device that will sample the data between these markers and play it paly repetiively at 1000 times the original sample rate. The software I use can sample as low as 6000 bps.

IOW if the PC outputs a 20KHz sinewave, the upscaler would convert it to 2MHz. That is the highest frequency I would need.

This is a bit out of my field so I need tom learn a bit. But I need a starting point. Can anyone advise me on the most relevant design consdierations for this project and how they might be best applied?

Thank you,

Lou Dremer

Reply to
Lou Dremer
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x1000 is 20MHz. You would need an FPGA driving a high speed D2A.

Reply to
linnix

As i was reading your request, i immediately thought of using MIDI (note on, note off, etc) for commanding a generator that will generate what you need. Not exactly what you mentioned, but a possible approach. However, one could make a "recorder" that is controllable (record on, record off, play) that always "multiplies" the input at a given rate, then any memory that acts like a shift register will do for the recorder; just alter the clock rate between input and output rates. Then you could change that output rate as you might need in the future.

Reply to
Robert Baer

You indicate that the signals will have modulation. Scaling the frequency by

100 in this manner will alter the characteristics of your modulation. e.g. if you AM a 1 kHz tone onto a 10 kHz carrier, then speed the whole thing up by 100, a demodulator will extract a 100 kHz tone from the 1 MHz carrier. Is this what you intend?

If you want the modulation to remain constant while the carrier frequency changes, you need a mixer, not a multiplier.

Or do you plan to adjust ("slow down") the modulation before applying it to the signal?

Steve

Reply to
Steve

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