[geocentrism] Re: MS illogic
- From: "philip madsen" <pma15027@xxxxxxxxxxxxxx>
- To: "geocentrism list" <geocentrism@xxxxxxxxxxxxx>
- Date: Sun, 29 Apr 2007 10:48:03 +1000
The distance between objects is invariant , since the difference in GC and HC
is just where you are standing.
So time delay on light paths can't be used to separate the systems.
No corrections..an A
Robert
Robert, I don't think you got my question.. I have to get graphic.. assume
the HC system.
Draw a circle around a point called Sol. It has a 90million mile radius
180million miles across.
Put a probe at the top of the page heading north towards alpha Centauri. and it
is say already 1000 million miles from the sun. If the earth was at position A
closest to the probe it would be 910 million miles away. At this time of the
year at this orbital position it would take 81 minutes for a command radio
signal to reach the probe, and another 81 minutes for the response to return..
a total delay of 162 minutes.
6 months later the earth is on the opposite side of the solar system and a
further 180 million miles from the probe (not counting in the extra distance
probe has travelled) . which will roughly add another 16 minutes each way or 32
minutes to the delay time ..
surely this anomaly would be noticed if it happened, especially when we went
full circle and found the delay coming back to shorter when we returned to the
starting point A.
Please reply...
Next question.
If we took measurements of the transmission frequency from the probe on the
other two quadrants when the distances were equal. If the earth was indeed
orbiting , then we would measure the doppler effect between when the earth was
receeding versus approaching the probe, factoring in of course, + or - the
probes expected velocity.
If there is no doppler frequency shift then the earth aint movin..
A rough, general figure for the Earth's mean orbital speed is 30 kilometers per
second (km/s), or 18½ miles per second (mi/s).
Thats 66,000 mph----there's a lot of doppler there.
Easy one... An interesting article on doppler effect by the radio amateurs
society.. Graph selected below for a car on 100kph.
Doppler shift is a phenomenon which is commonly observed by the lay person, yet
still confuses many amateur satellite operators. This page intends to
de-mystify Doppler and presents typical Doppler scenarios for low Earth
orbiting satellite operation.
http://www.qsl.net/vk3jed/doppler.html
Phil.
Firstly, the amount of Doppler shift for LEO at 800 km varies within these
ranges:
Band 15m 10m 2m 70cm 23cm 13cm 3cm
Freq. (MHz) 21.280 29.400 145.900 435.070 1269.000 2401.000 10250.000
Max Doppler +/- 477 Hz +/- 659 Hz +/- 3.27 kHz +/- 9.76 kHz +/- 28.5 kHz
+/- 53.8 kHz +/- 230 kHz
Table 1. Maximum Doppler Shift Vs Frequency for Popular Amateur Bands for an
LEO at 800km Altitude.
The table above shows how Doppler shift increases with frequency. For SSB/CW,
it should be obvious that Doppler will significantly impact operations on any
of the bands given, and must be compensated for. However, for FM, the Doppler
shift on 2 metres (3.27 kHz) is still small enough to be workable (with some
distortion) on a fixed frequency receiver. On 70cm, even FM receivers much be
retuned 3 or 4 times during a typical pass. By the time one gets to 10 GHz,
only wideband modes and/or computer controlled stations would be able to cope
with the severe Doppler shift one would encounter. However, 10 GHz isn't used
on any current LEOs, but will be active on Phase 3D, where the higher orbit and
slower satellite motion will mean the Doppler shift will be less in magnitude,
and less variable over a given short time period. Just for comparison, here's
typical Doppler shifts for a car travelling at 100 km/h. Hardly enough to keep
you reaching for the VFO dial, unless you operate on bands over 23cm, but 10
GHz mobile SSB would be interesting indeed! :-)
Band 15m 10m 2m 70cm 23cm 13cm 3cm
Freq. (MHz) 21.280 29.400 145.900 435.070 1269.000 2401.000 10250.000
Max Doppler +/- 1.76 Hz +/- 2.44 Hz +/- 12.1 Hz +/- 36.2 Hz +/- 105 Hz
+/- 199 Hz +/- 849 Hz
Table 2. Maximum Doppler Shift Vs Frequency for Popular Amateur Bands for a car
travelling at 100 km/h.
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