I’ve been trying to find GPS chips or devices that receive L1 and L2C and from a quick google search they seem to be very professional equipment, very bulky with huge antennas.

This makes me wonder how much power do they need, does it really take that much effort to calculate for the ionospheric interference?

At what rate would the GPS need to receive from 1Hz to 50Hz to calculate for the ionospheric delay that the use of L2C is so limited in 2018, even the Chinese phone got second frequency, L5, which is useless as it’s not even deployed yet, but second frequency nonetheless, on a pocket device.

Yet the most we get is L1 + SBAS + maybe pointless DGPS that works if we have a ground station nearby which helps guide ships with cm precision. This setup is BadElf Surveyor. Instead of adding L2C they added Glonass which doesn’t do anything for accuracy..


1 Answer 1


How much computing power ... ?

I am not able to quantify exactly in terms of FLOPS, but it is very cheap.

An example algorithm for a dual frequency user is described in chapter of the User Interface specification IS-GPS-200. The usage of ionospheric data from subframe 4 page 18 for a single frequency user is described in chapter I would guess that the computations for the ionospheric model are slightly more expensive than the dual frequency approach.

At what rate would the GPS need to receive ... ?

The position update rate is irrelevant. A receiver can measure ionospheric refraction without ever computing a position solution.

Dual frequency is not a panacea to enhance position accuracy. In fact, it does not help much until you

  • use a multipath supressing antenna
  • use a wideband RF frontend and a high IF sample rate
  • take coherent measurements on two frequencies (cheap chipsets only allow to switch back and forth)

There is no mass market for these solutions, so they remain expensive. Smartphones need chips that perform in urban canyons and indoors, not centimeter accuracy.


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