On 08/21/2013 03:51 AM, Ed Palmer wrote: > Adrian, > > I used Timelab to assess the reaction of the DTS-2077 to different > sine wave inputs. The differences in the noise floor are surprising. > The attached picture was made by taking the output of an HP 8647A > Synthesized Generator through a splitter, and then through different > lengths of cables to the inputs of the DTS-2077. The combination of > splitter and cable loss meant I couldn't get +7 dbm @ 1 GHz. If I > could have, the 1 GHz line might have been lower than it was. This is not very surprising. As you increase frequency, the slew-rate changes, and as slewrate increases, it convert noise to jitter to a lesser degree. Formula for slew-rate:
S = A*2*pi*f where A is the amplitude and f is the frequency Formula for jitter T = e_n / S where e_n is the noise RMS amplitude, S the slew-rate and T the timing jitter RMS. As you get closer to the instruments internal jitter, which forms a floor, the increased slew-rate does not improve as quickly as you would think. Cheers, Magnus _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
