Украина будет развивать ГЛОНАСС (2/2) / Навігація, маршрути, дороги

Если откинуть в сторону аппаратные отличия и попытаться их скопировать:
так а что писать, если спецификации по закрытой части отсутствуют? Одно дело когда huawei копировало прошивки доступных коммерческих продуктов cisco, снабженные комментариями и информацией изнутри компании, другое дело - когда нужно получить спецификации чипов, которые распространяются только в ограниченном количестве ведомств - МОб, ЦРУ, ФБР, АНБ, пожалуй всё.

Вот информация от USNO:

The Standard Positioning Service (SPS) is a positioning and timing service
which will be available to all GPS users on a continuous, worldwide basis
with no direct charge. SPS will be provided on the GPS L1 frequency which
contains a coarse acquisition (C/A) code and a navigation data message.
SPS provides a predictable positioning accuracy of 13 meters (95 percent)
horizontally and 22 meters (95 percent) vertically and time transfer
accuracy to UTC within 40 nanoseconds (95 percent).

The Precise Positioning Service (PPS) is a highly accurate military
positioning, velocity and timing service which is available on a worldwide
basis only to users authorized by the U.S. PPS data is transmitted on GPS
via the P(y) code on both L1 and L2 frequencies. PPS was designed primarily
for U.S. military use. It will be denied to unauthorized users by the use of
cryptography. PPS is made available to U.S. military and Federal agencies,
and to selected allied militaries and governments.

GPS SIGNAL CHARACTERISTICS
==========================
The satellites transmit on two L-band frequencies: L1 = 1575.42 MHz and
L2 = 1227.6 MHz. Three pseudo-random noise (PRN) ranging codes are in use.
The coarse/acquisition (C/A) code has a 1.023 MHz chip rate, a period of
one millisecond (MS) and is used primarily to acquire the P-code. The
precision (P) code has a 10.23 MHz rate, a period of seven days and is the
principle navigation ranging code. The Y-code is used in place of the
P-code whenever the anti-spoofing (A-S) mode of operation is activated.
The C/A code is available on the L1 frequency and the P-code is available
on both L1 and L2. The various satellites all transmit on the same
frequencies, L1 and L2, but with individual code assignments. Due to the
spread spectrum characteristic of the signals, the system provides a large
margin of resistance to interference. Each satellite transmits a
navigation message containing its orbital elements, clock behavior, system
time and status messages. In addition, an almanac is also provided which
gives the approximate data for each active satellite. This allows the
user set to find all satellites once the first has been acquired.

Future coded civil signals include a second signal L2C at the L2 frequency
and a third for safety-of-life applications L5 at 1176.45 MHz. There is
also an M code for military use to be broadcasted on L1 and L2.