Re: [time-nuts] Re Danjon Astrolabe

Brooke Clarke wrote: Hi Bruce: I'm interested in automatically measuring the earth's period by looking close to straight up with a fixed telescope. There are automatic star trackers that can "see" stars in the day time so the only time you would not see the star is when there's cloud cover.

[time-nuts] Fiber propagation delay tempco

Hal in July you asked > >/ With the fibre-based two-way time transfer. For shorter distances you > />/ can do well on coax, but for the distance range you require you really > />/ want to go fibre. That world is a bit different but can be made sense > />/ off. > / > How do I setup 2 clocks so the

Re: [time-nuts] Re Danjon Astrolabe

Poul-Henning Kamp wrote: > In message <[EMAIL PROTECTED]>, Brooke Clarke writes: > > >> A telescope and PIN diode might be the best way to get precise timings. >> If a fixed scope is used with a reticule where the star crosses twice or >> more then a plot of brightness vs. time will have a fl

[time-nuts] HP8505A programming info

Does any one have any programs written relating to frequency measurements of any type for the HP 8505A Network analyzer? Better yet, a programming manual for it. Chuck Norton Frequency Standards & Services 2727 E. Palmer Park Blvd. Ste 100 Colorado Springs, CO. 80909-5068 719-228-0540 voice 71

Re: [time-nuts] Re Danjon Astrolabe

In message <[EMAIL PROTECTED]>, Brooke Clarke writes: >A telescope and PIN diode might be the best way to get precise timings. >If a fixed scope is used with a reticule where the star crosses twice or >more then a plot of brightness vs. time will have a flat top pulse for >each line crossed.

Re: [time-nuts] Re Danjon Astrolabe

Hi Bill: When C-Band satellite TV first started the dish I used came from a Mills Cross array at Stanford consisting of maybe 16 each 10' diameter spun aluminum dishes used to study the features of the Sun at about 2.something GHz. This took up some number of acres of land. The hour angle of

Re: [time-nuts] Re Danjon Astrolabe

I wonder if it is possible to use radio astronomy. You'd have to find an object that doesn't require a very large antenna to acquire its signal. Collins Radio once built a sun tracker for the Navy that used microwave radiation from the sun. The antenna was driven by a servo that maximized the sign

Re: [time-nuts] Re Danjon Astrolabe

Hi Bruce: I'm interested in automatically measuring the earth's period by looking close to straight up with a fixed telescope. There are automatic star trackers that can "see" stars in the day time so the only time you would not see the star is when there's cloud cover. By using a reticule it sh

[time-nuts] Re Danjon Astrolabe

> > In article <44D8C0BB.1030608 at pacific.net > >, Brooke Clarke > > writes > >/Hi Geoff: > />/ > />/Thanks for the reference to "Geodesy". Do you know if the first edition > />/h

Re: [time-nuts] Minimising effective divider propagation delay

Dr Bruce Griffiths wrote: > Brian O'Connor <[1]vk4gtw at bigpond.com> wrote: > >> I note that Shera's QST article refers to using the 1 MHz >> output from a HP5328A. Is there any degradation of >> performance or increased thermal sensitivity due to the use >> of a HP marked 7490 (ripple counter

Re: [time-nuts] Time interval interpolation by sampling a pair of sinewaves in quadrature.

Dr Bruce Griffiths <[EMAIL PROTECTED]> wrote: > Yet another high resolution time interval interpolation technique is to > sample a pair of quadrature sinewaves at the leading edge of the pulse > to be time stamped. These are all variants of what I (because of my high-energy physics background!)

Re: [time-nuts] Minimising effective divider propagation delay

Dr Bruce Griffiths wrote: > Brian O'Connor <[1]vk4gtw at bigpond.com> wrote: > >> I note that Shera's QST article refers to using the 1 MHz >> output from a HP5328A. Is there any degradation of >> performance or increased thermal sensitivity due to the use >> of a HP marked 7490 (ripple counter

[time-nuts] Minimising effective divider propagation delay

Brian O'Connor <[1]vk4gtw at bigpond.com> wrote: > I note that Shera's QST article refers to using the 1 MHz > output from a HP5328A. Is there any degradation of > performance or increased thermal sensitivity due to the use > of a HP marked 7490 (ripple counter) to divide down to 1 MHz? > Would u

[time-nuts] Time interval interpolation by sampling a pair of sinewaves in quadrature.

Yet another high resolution time interval interpolation technique is to sample a pair of quadrature sinewaves at the leading edge of the pulse to be time stamped. When sampling a pair of 10MHz sinewaves in quadrature with a 12 bit ADC a timing resolution of better than 50 picosec is possible. Wi

[time-nuts] Centroid pulse timing

Another way of determining the the arrival time of a pulse with high resolution is to use centroid timing techniques. The input pulse is converted to a short pulse using a delay line timed monostable then the resultant pulse is low pass filtered by a discrete component RLC Gaussian low pass filt

Re: [time-nuts] Time interval counters

Hal Murray wrote: Suitable TDC chips are available from [1]http://www.acam.de/ [2] In particular the TDC-GP1 has a resolution of better than 250picosec with a range of 200 millisec, which should be more than adequate for measuring the time delay between GPS and local standard derived PPS p