Starlink signals can be reverse-engineered to work like GPS

Re:Starlink signals can be reverse-engineered to work like GPS by Qqqwxs on Friday October 21, 2022 @10:51AM (#33288594)

> What the US government did was remove the bias from the CA code so it could be used for precise positioning. The military still uses P codes as well. I believe there is a small gain to be had but it’s due to frequencies.

The precision of positioning from the P code is 10 times greater than the C/A code (about 30cm vs 3m). This is due to the wavelength/'chip length' of the code signal which is modulated onto the carrier wave (10.23 Mhz / 29.31 m wavelength for P code, 1.023 Mhz / 293.1 m wavelength for C/A code). Positioning precision is limited to about ~1% of the chip length by signal processing.

[ Parent | on HN ]

Re:Starlink signals can be reverse-engineered to work like GPS by WJW on Friday October 21, 2022 @12:55PM (#33290274)

This is correct, but I'd like to add that at some point the errors from which frequency and code you use is no longer the dominant factor in the position error. Depending on where you are, either multipath errors (eg due to reflections from buildings or mountains) or athmospheric errors (ie due to the radio signal being distorted in the ionosphere) start to dominate.

[ Parent | on HN ]