> The reason is that UHF TV stations radiate energy at between 470 and 854
> Mhz at power levels up to 1000kW ERP. Their siting on high ground means
> we might be flying level with the antenna and therefore in the area of
> most intense energy. An inevitable consequence of radio frequency
> generation and amplification is the production of harmonic energy which
> is normally suppressed by filtration yet can still be of a high enough
> level to disturb GPS receivers. The highly sensitive front end of
> satellite receivers will be overwhelmed by the offending RF energy
> swamping the ephemeris data and timing information necessary for
> position and velocity calculations.
Thank You.
That would explain my problem south of Auckland. The offending
television mast is on a hill at an altitude of 3510 feet AMSL and I regularly
transit past it between 2500 and 3500 feet. You can guarantee that it
knocks out GPS coverage every time.
And before you wonder, the hill goes straight up from 100 feet AMSL
and is part of a 60 mile long ridge - great for ridge soaring or
exercising your feet when flying a 172! Roll on the glider wings.
Now, what does a Navaid wing leveller that is GPS coordinated do when it
loses coverage?
Tony
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