qeek you should stop the deceit or maybe it's just ignorance? TV GPS radar all work off High Frequency waves now. You don't need satellites for Skywave, Groundwave or Line of Sight transmissions. Put the Kool-aid down and come join us in this brave new world that was discovered in 1921....
https://en.wikipedia.org/wiki/Skywave
Good grief - you really do think we RE'ers are stupid don't you? Don't you imagine that we occasionally look stuff up?
Yes we do...and 3 minutes of googling reveals that "skywave" transmissions send a signal up from the ground - it bounces off of this layer in the atmosphere called "The Ionosphere" and thereby gets picked up on the ground...for 100% sure, that works.
HOWEVER: For navigation, you need to measure your distance from at least three sources. Right? If you want to know your position accurate to the 3 to 10 meters that GPS is accurate over - then you have to know how far the radio signal travelled...to within at least that precision.
With satellites - you know their position VERY accurately - they orbit at precise altitudes.
But with a "skywave" system, the distance the radio wave travelled is the distance from the transmitter to the ionosphere plus the distance from the ionosphere back to the receiver.
So for us to use skywave as a navigational system, we'd need to know the height of the ionosphere above the ground to a precision of better than 1.5 to 5 meters.
OK so how accurately do we know the height of the ionosphere?
Well, the D-layer (which is responsible for this 'skywave' refraction phenomenon) is described here:
https://scied.ucar.edu/ionosphere "The D region is the lowest, starting about 60 or 70 km (37 or 43 miles) above the ground and extending upward to about 90 km (56 miles)."
Oh..."about"?!? No! "about" isn't good enough. We need the distance accurate to a meter or so! It could be anywhere from 60 to 70km? Well that could change the distance that the radio waves travel by as much as 20km! So if GPS worked the way you fondly imagine it might - then it would only be just barely accurate enough to tell you which city you're in...not which lane of the freeway you're on!
Worse still - this kind of communication only works in the HF band - which has wavelengths in the ten to one hundred metres range. That means that to receive it, you'd need a 5 to 50 meter antenna.
Just how big *IS* your cellphone?
GPS signals are in the 1.5GHz range - (UHF) which allows for a 5 centimeter antenna...which fits handily into phones and satnavs. But UHF signals don't bounce off of the ionosphere...they go right through it like it wasn't even there.
You also pointed out that VHF signals can also bounce - but only at certain times of the day and year...that's hardly useful for 24/7 GPS uses is it? Also, TV signals are VHF - and have you seen the size of antenna you need to get decent reception? Yeah - about a half meter to a meter...still not fitting into a cellphone!
(Maybe your cellphone came with a pair of "rabbit ear" antennas?)
So - GPS cannot POSSIBLY use HF, so it doesn't bounce off the ionosphere. It uses UHF, which very notably DOES NOT bounce off of the ionosphere - and cannot go "over the horizon". The refraction of the radio waves is fairly minimal, and high quality GPS units have software to estimate the degree of refraction in order to get slightly more precise positioning.
Old-school GPS's like my old Garmin sport-trac actually showed you which satellites it had found - and every few minutes, one would disappear over the horizon and a new one come up to replace it. That doesn't work for balloons or tall towers or signals bouncing around in the atmosphere.
So no - you are COMPLETELY wrong - and for two entirely different and easily checkable reasons.
Why not check things like this before you post? The information is ridiculously easy to find. The people you're talking to here are SMART PEOPLE. We're going to look stuff up and think about it - you really can't just guess at answers without being called out and made to look pretty stupid.