Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > sci.electronics.design > #518562

Re: really bad oscillators

Show all headers | View raw

John Larkin wrote
>A timestamper is a circuit that latches the time of arrival of a pulse
>edge. We use a clock and a binary counter as MC, the master counter
>definition of time. We extend those MC bits down into picoseconds with
>a time interpolator, adding 8 to 12 bits below the counter LSB.
>
>One way to test a time stamper is to stamp pulses that are random in
>time, and then histogram/analyze the codes. That can catch all sorts
>of nasties, like stuck or shorted bits or interpolator problems; we've
>done the math on that. In the test set that I'm designing, I want a
>simple but really bad pulse generator, maybe around 1 MHz with tons of
>period jitter, to get good statistics and never alias against the
>master clock. Aliasing can make really weird histograms.
>
>https://www.dropbox.com/s/vv6dqeffxrkmca3/Timestamp_Noisy_Osc.jpg?raw=1
>
>The single inverting schmitt oscillator is probably good enough, but
>it's fun to consider other really nasty oscillators. A bad power
>supply will only help.
>
>We have an FPGA, so I guess we could build a pseudorandom bit stream,
>filter that a little, and use that to confuse a schmitt oscillator.
>The kids might enjoy programming that.

74HC4046 with the VCO input connected to noise source?
Radioactive decay, noise diode...
?

Back to sci.electronics.design | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

really bad oscillators John Larkin <jjlarkin@highlandtechnology.com> - 2018-10-06 10:33 -0700
  Re: really bad oscillators "Tim Williams" <tiwill@seventransistorlabs.com> - 2018-10-06 12:51 -0500
    Re: really bad oscillators whit3rd <whit3rd@gmail.com> - 2018-10-06 15:16 -0700
      Re: really bad oscillators John Larkin <jjlarkin@highlandtechnology.com> - 2018-10-06 15:52 -0700
      Re: really bad oscillators "Tim Williams" <tiwill@seventransistorlabs.com> - 2018-10-06 22:55 -0500
  Re: really bad oscillators George Herold <gherold@teachspin.com> - 2018-10-06 11:33 -0700
  Re: really bad oscillators John Larkin <jjlarkin@highlandtechnology.com> - 2018-10-06 11:35 -0700
  Re: really bad oscillators <698839253X6D445TD@nospam.org> - 2018-10-06 18:49 +0000
  Re: really bad oscillators Steve Wilson <9fe142ac@gmail.com> - 2018-10-06 11:50 -0700
  Re: really bad oscillators bloggs.fredbloggs.fred@gmail.com - 2018-10-06 12:13 -0700
    Re: really bad oscillators John Larkin <jjlarkin@highlandtechnology.com> - 2018-10-06 15:55 -0700
  Re: really bad oscillators Gerhard Hoffmann <ghf@hoffmann-hochfrequenz.de> - 2018-10-06 21:28 +0200
    Re: really bad oscillators Gerhard Hoffmann <ghf@hoffmann-hochfrequenz.de> - 2018-10-06 21:35 +0200
    Re: really bad oscillators John Larkin <jjlarkin@highlandtechnology.com> - 2018-10-06 16:01 -0700
  Re: really bad oscillators bitrex <user@example.net> - 2018-10-06 21:59 -0400
    Re: really bad oscillators John Larkin <jjlarkin@highlandtechnology.com> - 2018-10-07 08:05 -0700
      Re: really bad oscillators bitrex <user@example.net> - 2018-10-07 23:04 -0400
        Re: really bad oscillators John Larkin <jjlarkin@highlandtechnology.com> - 2018-10-07 21:10 -0700
      Re: really bad oscillators bitrex <user@example.net> - 2018-10-07 23:12 -0400

csiph-web