Question: Can we duplicate or fake a pulsar? If so, could we mess up people's
navigation? Could we interfere with signals from a pulsar? Or cancel them via
some form of interference?
Question: When establishing our own space beacons (SPS
- GPS in space), would we use some sort of
pulsar like signal, but with more uniqueness?
Apology/Rebuttal:
Bob,
Normally I don't respond to allegations*[1] of veiled US bashing, but in this
case I must make an exception. I am aware the US owns, built, and (AFAIK)
entirely paid for the GPS satellite constellation. I am aware of the limits of
the accuracy and several techniques of getting around (or attempting to) the
inaccuracies that can be introduced into the data feed. Anyone who uses this
system other than the Americans (and maybe a Redcoat or two) are in the 'buyer
beware' (and given you paid nothing, that's a capital B in beware!).
You did not, in fairness, mention that the US can also (you did build, and did
pay for, and do
own - AFAIK - the constellation) turn off the
feeds from some satellites entirely or probably even deactivate the whole
shebang if it really wants to black out an area.
None of this is a statement of anything other than the facts as I know them. I
don't believe there was any conclusion suggested herein.
FWIW, the 'veiled US bashing' was extremely veiled, as I, the author of the
comment, totally failed to perceive it. I am not the type to take veiled shots
at anyone.... it is not in my nature. I'll come out and say what I think in
plain language. I understand the desire to defend ones country, although I'm a
little offended that you'd think I'd stoop to petty sniping at the
US.*[2]
However, perhaps it is the quintessential Canadian lurking inside, but I will
apologize for causing any unintended harm and for phrasing my factual comments
in such a way as they might seem to be US bashing if one was apparently more
sensitive than I was to that possibility. My apologies.
And my thanks to Brian for succinctly defending me. <tips hat>
And let me conclude by saying that I'm very glad to be on the same continent
as the USA (as opposed to any number of other options), I expect to enjoy
beating and being beaten by Americans at ECC next weekend, also that I'm very
glad to have so many good American friends (Bob among them), and I'm very
proud to be Canadian! These things are in no way mutually exclusive!
Tomb
[1] Alleged because there was neither intention,
nor I believe with a dispassionate review, evidence to support such an
allegation wthout a
fair degree of speculation as to some (non-
existent) context or agenda behind the comments rather than from the meat of
the comments themselves.
[2] Now, US Bashing was what went on when I
sent Jon Davis a jibe about our Women's Hockey Team winning.... but that did
include a number of smileys! All in good fun and merely a preamble to me
beating Jon at Formula De in Lancaster! *as Tomb utters famous last words* And
US Bashing as it pertains to Hockey is NOT petty sniping at the US. It's
HOCKEY we're
talking about.....!!!!! ;)
Tom:
> Can we duplicate or fake a pulsar?
About the time we can build a Dyson sphere, I'd imagine.
> And US Bashing as it pertains to Hockey is NOT
<grin> So from a Canadian's point of view, it's sniping at *religion*.
> On Sat, Feb 23, 2002 at 10:52:47AM -0500, Thomas Barclay wrote:
Unlikely. A pulsar is a rather powerful star flashing rather quickly. Blocking
it would require at least a stellar sized
object. Interference /could/ be possible - plonk a blackhole between
the star and the ship and bend the light away from the ship?
Kind of tricky to organise...
> Question:
Pulsars are a) VERY bright and b) very unique. Their flash rates are VERY
precise. From bearings on half a dozen you could fix position reasonably well.
Knowing a rough position (like: which system you're in) you could take fixes
on nearer stars and get positions down fairly
well. That's how the Hubble orients itself - it knows about "key"
stars and fixes on them - obviously you need to know the rough
apparent magnitude of them before you can identify them in the sky to take
bearings. Pulsar light comes with the encoded flashing to tell them apart.
> Normally I don't respond to allegations*[1] of
ISTR the precise timing information for sub-100m positioning comes in
a secondary databand which was (until recently) encrypted. It's the
unencrypting of this band that's made GPS as a traffic navigation aid
Tomb,
Well I will publicly apologize for seeing what was not there in your
statements. Maybe I am just getting paranoid. <G>.
Thank you for the reply and once again I am glad to be a member of this list
where we can behave in a civilized manner.
In mitigation I will say that this is during a LosCon
and I have been working on 3-4 hours of sleep for a
couple of days <G>.
Take Care,
Bob
Sorry to the rest of the list for leaving most of Tom's post. I cannot see a
good place to cut it that would maximize "face" for us both. <G>
> --- Thomas Barclay <kaladorn@magma.ca> wrote:
On Sun, 24 Feb 2002 04:37:42 -0800 (PST) Robert Makowsky
> <rmakowsky@yahoo.com> writes:
There is a fine line sometimes between paranoid enough and too paranoid
[although I have coworkers who prefer. "I know I'm being paranoid but am
I being paranoid enough?" All tounge in cheek (I think... hope...)]
> Thank you for the reply and once again I am glad to be
Yeah, life is good on this list.
> In mitigation I will say that this is during a LosCon
A bit jealous here, we had to cancel the local convention in March (long
story.)
> Take Care,
Here, let me. <grin, snip>
Gracias,
> On 23-Feb-02 at 11:29, Thomas Barclay (kaladorn@magma.ca) wrote:
Well, you could fake it if you want to go back into the past 50 years or so
and beam your fake to where your opponents will be.:)
> When establishing our own space beacons (SPS
Who is going to put in beacons that will only be good after the signal gets
across some large number of (light) years?
> You did not, in fairness, mention that the US can
We would have to shut down commercial air traffic to do this. They are relying
fairly heavily on it. For that matter they are placing GPS units in large
automated farm machines now. What I don't understand is how they are claiming
accuracy within inches when GPS is within a meter. The discussion on Science
Friday on NPR claimed increased yields by making the automatic weeding closer
to the plants.
Oh, and as for the bashing. Either:
1. It's true, and we should either fix it or shut up about it.
2. It's false and not worth getting upset about.
> What I don't understand is how they are claiming accuracy within
I believe they're using ground stations which have a beacon. That helps to
reduce the error down to very small amounts.
> > What I don't understand is how they are claiming accuracy within
There are three grades of GPS unit - civilian, commercial and military
-
accuracy does vary depending on the category - and will vary within the
category depending on the quality and the age of the unit in question.
Civilian units will give you a potential accuracy of 1 metre with an average
accuracy of 5 metres - Commercial airlines use better units with a
greater level of refinement that was more important when the dither factor was
still
active - Military units can give potential accuracy of centimetres with
an average accuracy depending on the number of satellites "overhead" of about
30-50 centimetres. I have worked with all three types and found that
military units were great but generally unavailable to the public and
commercial models can cost more than military units....
> I believe they're using ground stations which have a beacon. That
Differential beacons are in use in many countries but have limited range
-
usually 250-300 km - (not much use in the middle of a desert or the
ocean)
and are generally confined to major cities and heavy air routes - the
expansion of the DGPS network in most countries has stalled due to the
dropping of the dither factor for civilian use.
Quoting Roger Books <books@jumpspace.net>:
> On 23-Feb-02 at 11:29, Thomas Barclay (kaladorn@magma.ca) wrote:
Erm. Us?
We have sent out messages that are unlikely to be read inside the next 50,000
years. Sometimes people can be long-term about things...
> > You did not, in fairness, mention that the US can
I don't know about in the US, but in Europe I was under the impression that we
> On 25-Feb-02 at 09:01, katie@fysh.org (katie@fysh.org) wrote:
That was a short term relatively inexpensive publicity stunt. The costs to put
out something that will have enough power to be a "space GPS" in normal space
requires a huge investment that will come into affect after the builders and
politicians have retired.
Quoting Roger Books <books@jumpspace.net>:
> On 25-Feb-02 at 09:01, katie@fysh.org (katie@fysh.org) wrote:
I dunno. I've met a few humans. At the point where we /can/ put out
stellar energies, I'm inclined to think someone will.
"Nike logo at 156 mark 7, Coca-cola at 034 mark 23, AOL logos at 234
mark -2,
Roger Books
> > Who is going to put in beacons that will only be good
Katy:
> Erm. Us?
Roger:
> That was a short term relatively inexpensive publicity stunt. The
Might want to change that to "may require" and "might not come into
effect"--kind of hard to be sure whether it'll be economical in 150+
years. If we put in a beacon at a number of stars, they'll be usable after
just a few years--how many years depends on how many stars, of course.
[quoted original message omitted]
katie@fysh.org schrieb:
> It still represents a long term investment - not everyone
Indeed, there are projects like the 10,000 year clock:
http://www.wired.com/wired/archive/6.05/hillis.html?person=marvin_mins
ky&topic_set=wiredpeople
Greetings