What is your definition of low noise / purity ? DDS and low noise take some pretty good engineering.
What is the min frequency ? What is the step size ? As to PTS's it took me around an hour to make a cable write the C code to convert to its interface needs. If I had not lost the documentation I'd send it to you. If your looking for new, look on the web a Microwave Journal's web site http://www.microwavejournal.com/ and a couple of the military mags http://www.militaryaerospace.com/index.html for example. How many steps in a test run ? An 8645A can do 4K step at a time. But alas it is a pretty old instrument, Kesight recommends the E8257D but starting price is over $33K On Tue, Oct 7, 2014 at 10:32 AM, Magnus Danielson < mag...@rubidium.dyndns.org> wrote: > You should be able to use DDS test-boards and by timing your last write, > you should be able to time the frequency jump. > > The STEL-1173 takes 6 bytes, but writing the last one latches all 6 bytes > over to a single 48 bit word. I expect that other DDSes have the same > distinct transfer-phase if you only look in the datasheet for the details. > > Some of the modern DDSes can take 10 MHz directly and step it up > internally before hitting the DDS core, but it may be that you need to > synthesize a higher clock from the 10 MHz first. > > Cheers, > Magnus > > On 10/07/2014 07:02 PM, Jim Lux wrote: > >> >> At work, I'm putting together a multichannel stepped frequency CW radar >> breadboard, and I'm looking for something to serve as a source that I >> can step quickly. >> I'm looking at stepping every millisecond or so. Right now, I use a >> Ardunino type microcontroller driving a serial DAC driving a VCO, but >> that's a bit wonky and noisy, although it's easy to get the step timing >> right on. The spectral purity is, shall we say, downright ugly. >> >> Since I'm going to be doing precision ranging with this, the spectral >> purity has to be reasonably good (not 1E-15 at 1000 seconds good, >> fortunately).. >> >> I was thinking about a PTS synthesizers (beloved of time-nuts for all >> kinds of reason), and they're nice because they are quiet, and switch >> really fast (microseconds). However, they all seem to have BCD or GPIB >> interfaces (only). Sure, I can code up something on an Arduino or other >> microcontroller to drive the BCD on the PTS, but maybe there's something >> else out there that might work as well? And is already off the shelf. >> >> >> I could hook a Prologix on the back of a PTS with GPIB, and hit it over >> the ethernet, but I'm not sure I'd be able to get the steps to occur >> when I want them (ethernet and determinism do not go well together). >> >> Maybe some DDS in a box product? That will take my nice clean 10 MHz >> reference? >> >> Ultimately, I'm looking at output frequencies in single digit GHz, but >> something that can be mixed/multiplied up will work just fine. >> >> I'm looking for something that is off the shelf-ey as much as possible. >> Using surplus gear is ok, because I really only need 3 or 4 channels and >> that might be scroungeable, but spending hours wiring up weird adapters >> or locating connectors that haven't been made since 1943 is something >> I'd like to avoid. >> >> >> _______________________________________________ >> time-nuts mailing list -- time-nuts@febo.com >> To unsubscribe, go to >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> and follow the instructions there. >> > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/ > mailman/listinfo/time-nuts > and follow the instructions there. > _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.