Poor Joe,
Aren't you aware these items are no longer of concern. All of the
newest products are NGDS .. next generation defined software. Forget to
decouple the USB power -- no problem. The latest software version will
switch in a proper 'software generated' components.
Oh yeah, no need to adjust anything. The software will properly detect
any connections and settings for any rig. You don't even have to call
CQ - NGDS will do that, make contacts, create an ADIF log and submit
it for you. No silly operator intervention is necessary.
<grin>
PS. Of course the software can also generate a winning certificate.
Now if it could only frame and hang it ???
73 de Phil - N8PS
Quoting "Joe Subich, W4TV" <lists@subich.com>:
It's not like simple AFSK, where you just need to follow the
manufacturer's instructions.
Only follow the manufacturers instructions if the manufacturer knows
how to give valid instructions - unlike some PhDs who think they can
increase the speed of light by almost 50% at will.
Manufacturers who skip the chipmaker's recommended regulator for the
sound ADC, who fail to properly decouple (filter) the USB power, who
fail to regulate the V/2 reference for their op-amps and who fail to
adequately decouple their power distribution bus certainly can't be
trusted to know what they're doing when it comes to instructions
about setting AFSK levels.
73,
... Joe, W4TV
On 3/15/2014 7:30 AM, Kai wrote:
You're quite right Chen. At the risk of annoy the moderator with
off-topic discussions, time-of-flight is not all that needs to be
measured, but it is necessary to a certain precision. The probe signal
is quite a bit more sophisticated. The signal bends in three dimensions,
separates into counter rotating waves of circular polarization that
travel different paths and at different propagation velocities, possibly
reflects and diffracts from the gray line region and Auroral oval
boundaries. It is subjected to multipath and ISI, and so on. It's a
digital signal designer's heaven (and a propagation weenie's heaven)!
Competing theories predict different paths, as well as different
multipath, and differing propagation velocities. The ionosphere is
complex, and then you add the Earth magnetic field, and things get
really interesting in a hurry (think CRT). It's not like simple AFSK,
where you just need to follow the manufacturer's instructions.
73,
Kai, KE4PT
On 3/15/2014 12:23 AM, Kok Chen wrote:
On Mar 14, 2014, at 8:49 PM, Kai wrote:
We do however want to measure the propagation speed of signals in the
ionosphere...
There are more unknowns than measurables, Kai, if all you are
measuring is the path transit time. The problem is not the "baud
rate" (we know for example that it is easy to measure transit time to
much more precise than T, using a pulse whose width is T).
Think of a similar experiment where you use total internal reflection
of a prism in a reflex light path to measure the speed of a laser
beam. You don't know the size of the prism, nor the distance of the
laser to the prism, and you don't know the refractive index of the
glass used to construct the prism. All you can do is to measure the
transit time as precisely as possible. With that alone, you cannot
determine the refractive index of the prism.
Now imagine the prism to be a simple model of the ionosphere. (In the
case of the ionosphere, the density is not even constant.)
73
Chen, W7AY
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