[time-nuts] Slightly OT: inexpensiveUSB analog-digitalconverter?

[Ulrich Bangert]

Darrel,

I just found your homepage

http://www.dlharmon.com

WOW! What a project!

73 de Ulrich, DF6JB

> -----Ursprungliche Nachricht-----
> Von: time-nuts-bounces at febo.com 
> [mailto:time-nuts-bounces at febo.com] Im Auftrag von Darrell Harmon
> Gesendet: Donnerstag, 17. Januar 2008 05:11
> An: Discussion of precise time and frequency measurement
> Betreff: Re: [time-nuts] Slightly OT: inexpensiveUSB 
> analog-digitalconverter?
> 
> 
> John Miles wrote:
> > Is it just me, or is there a huge hole in the DAQ marketplace for a 
> > high-resolution, low-noise, low-to-moderate cost, _medium_-speed 
> > acquisition dongle?
> >
> > I've been planning to build a 100+ dB 24-bit USB DAQ 
> interface around 
> > the AD7760 for some time now, which would be good from DC-1 
> MHz.  That 
> > would be something like having a high-end sound card input with a 
> > 2.5-megasample ADC instead of an audio ADC.
> >
> > The only thing that's stopped me so far is the FPGA and USB 
> > interfacing work...
> >
> > -- john, KE5FX
> >   
> I would certainly consider building one if you designed it and made 
> gerber files or boards available.
> 
> I am currently finishing up a project with a 125 MHz 16 bit 
> ADC and an 
> FPGA digital down converter. The output rate is similar to what you 
> would have (32 bit IQ at 500 kHz, so 4 MB/s). This does not seem very 
> difficult with USB 2.0, but actually is quite difficult. I did 3 
> revisions of my board. The ADC and FPGA worked perfectly on the first 
> revision, and the second two revisions were due to USB interface 
> problems. I tried the Cypress FX2 and had nothing but 
> problems with it. 
> I am now using a Blackfin DSP and PLX NET2272 USB chip as the PC 
> interface. It works well. I have written a spectrum analyzer 
> application 
> for it and plan on doing some software defined radio work 
> with it soon.
> 
> Whatever you do, it would be best if the sampling rate could 
> be locked 
> to an external 10 MHz input. I did that with my board and expect to 
> write software in the next few months for frequency measurement.
> 
> Darrell Harmon, KI4MVK
> 
> 
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