Joseph, I took a look at the instrument instruction manual to see what is going on. In typical todayspeak, Symmetricom doesn't say how the gadget works. I make it what used to be called a Costas direct-conversion receiver. The test signal is connected to two mixers; the reference oscillator is connected to the other mixer inputs in quadrature. The mixer outputs are digitized and filtered, the Q signal is shifted 90 degrees from the I signal and combinted. The result is a baseband SSB dignal which is then Fourier transformed for display. Is this what you have in mind?
Dave Joseph Gwinn wrote: > In article <[EMAIL PROTECTED]>, > Joseph Gwinn <[EMAIL PROTECTED]> wrote: > > >>I may need a Dual Mixer Time Difference (DMTD) instrument, to measure >>picosecond changes in electrical length in a coax plus amplifier time >>reference signal distribution system with total delays in the hundreds >>of nanoseconds, currently operating at 10 MHz (sinewave), but with 100 >>MHz likely at some future date. >> >>What DMTD instruments are commercially available? A google search was >>not successful - all noise no detectable signal, probably because DMTD >>instruments are not that common, and many people build their own. > > > The silence, the silence. I have not found too many commercial DMTF > units, but I have found one, although the maker does not market it a > such: > > The Symmetricom 5120 > <http://www.symmttm.com/products_pn_adev_test_sets_5120A.asp> is at > heart a digital DMTD instrument, and will make all the usual DMTD > measurements, although it is marketed primarily as a phase noise test > set. > > What else is available? > > > Joe Gwinn _______________________________________________ questions mailing list [email protected] https://lists.ntp.org/mailman/listinfo/questions
