Paul Boven wrote:
Hi Tom, everyone,
Tom Van Baak wrote:
See: http://www.leapsecond.com/museum/pulsar for some
pulsar ADEV stability plots and links to many research papers
with all the details.
Your page starts with the question "if it was possible for an amateur to
receive pulsar signals?". Turns out you can, at least the particular
bunch of amateurs who have been restoring the 25m Dwingeloo radio
telescope (http://www.camras.nl).
This, and similar impressive accomplishments, has prompted some
lunchtime discussion at work (JPL).. One of us (N5BF) has been
contemplating what it would take to do an amateur EarthVenusEarth (after
some of his experiments doing EME with 5 watts)..
So, when talking about "amateur" accomplishments.. where do you draw the
line on using "big stuff". If you're an amateur who happens to have
access to Arecibo or to a DSN 70m dish, is that *really* an amateur
contact/event?
The same thing applies to timenuttery, to a certain extent.
So we thought.. if it's something that a single amateur can feasibly do
single handedly. Surely, no amateur is going to build Arecibo or a 70m
dish in their backyard.. but wait, what if you're Paul Allen building
the ATA at Hat Creek. Should happening to be wealthy enough to buy all
the toys exclude you.. after all, it's the "amateur" aspect, not the
"poverty" aspect.
Or, maybe it's the "fabrication" of the equipment that's the relevant
thing. I know I'd be more impressed by someone building a Cesium clock
from scratch in their garage more than just buying one off the shelf,
even if buying one is cheaper. Kind of like making your own vacuum tubes.
And, even, since those of us sitting around the lunch table do RF work
of one sort or another for a living, is *anything* we do with RF truly
amateur (leaving aside legalisms like pecuniary interests, etc.).
Maybe it's a sort of fuzzy definition.. you can fit it in a suburban
backyard (leaving out the 70m dishes, but not the EME array, as long as
you're not in the W5UN category)
Or time nuts wise, some aspect of self fabrication, whether it be
hardware, software, or even just an unusual configuration or kind of clock.
Could you do this with a more modest antenna? The lesser gain would need
to be compensated for by using as much bandwidth as possible (which
needs de-dispersion), and folding the signal by the pulsar period.
Folding in turn requires a stable clock, and compensating for the
doppler shift caused by the Earth's motions. I would say that receiving
the brightest pulsars is within reach of the bigger EME stations - but
still working on the calculations (and demonstration) to back this up.
This is kind of fascinating... When I got started in home time nut
territory, it was because I got a Z3801.. as a coworker put it, how
often do you have something accurate to way better than a part per
billion in your garage.
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