This article is intended for users of Android smartphones powered by Unisoc (紫光展锐) processors. In which it is possible to improve the performance of the GPS/A-GPS receiver through the system menu.

Entering the system menu of a smartphone on a Unisoc processor

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Default A-GPS settings

A-GPS is designed to help a smartphone find satellites.

CP and UP switching:User Plane.

AGPS Mode =MSB.

SGPS - A-GPS

• SLP Address = supl.qxwz.com
• SLP Port = 7275

IMSI.

SGPS - Information - Mode and System Config

• GPS+BD2+Galileo

1. Improved A-GPS settings

Run the ping command and determine which server has the highest speed of information exchange.

On a cellular operator in a 4G network, the result is as follows:

Conclusion- the shortest response time from supl.mts.ru and supl.google.com. The default value - supl.qxwz.com - is not optimal.

Server and port indicated:

SLP Address = supl.mts.ru
SLP Port = 7276

Abroad, the server supl.google.com will be optimal.

Port 7276- to protect TLS encryption.
TLS Enable.
Result: "cold start" and search for satellites after specifying

• supl.mts.ru
• 7276

With GPS+GLONASS+Galileo constellations, the TTF (Time To First Fix) satellite location time after turning on the smartphone is 33 seconds.

2. Selecting a combination of global positioning systems GPS/GLONASS/BeiDou/Galileo

The selection is made in the system menu in the SGPS - Information section.

My phone lists the options:

• GPS + BD2 + Galileo (mode No. 1)
• GPS + B1C + GLONASS (mode No. 2)
• GPS + B1C + Galileo (mode No. 3)

• GPS + GLONASS + Galileo (mode No. 4)
  *Custom

  sgps.png "SGPS"
  [/columns]

When choosing an option "Custom" A choice of system combinations is available when adding numbers:

For example, selecting the GPS + BD2 + Galileo menu item is equivalent to entering the numbers 1 + 2 + 16 = in the “Custom” menu 19.

2.1 Options for choosing global positioning systems

The numbers below are the values in the "Custom" menu.

1 - GPS

• advantage: quickly finding satellites - in 26 seconds. Simple calculations for a slow processor.
• disadvantage: there are few GPS satellites for a city where the horizon and sky are obscured by buildings.

2 - BeiDou BD2
doesn't work

3 - GPS+BD2

• advantage: works with one GPS
• disadvantage: cold start increased to 120 seconds.

4 - GLONASS

• dignity: no
  *disadvantage: few satellites to detect. There is no independent detection of coordinates.

5 - GPS+GLONASS

• advantage: there are enough satellites to find coordinates, quick location search, reliable satellite reception.
  *disadvantage: may not work if GPS signals are interfered with.

6 - GLONASS+BD2

• advantage: not sensitive to GPS interference, works.
• disadvantage: low accuracy: worse than 15 meters, coordinate search speed is 47-107 seconds.

7 - GPS+BD2+GLONASS
doesn't work

8 - BeiDou B1C
doesn't work

9 - GPS+B1C
Advantages and disadvantages as in paragraph 3.

10 - BD2+B1C
doesn't work

11 - GPS+BD2+B1C
doesn't work

12 - GLONASS+B1C

• advantage: not sensitive to GPS interference, works.
• disadvantage: loses satellites and finds them, no reliability.

13 - GPS+GLONASS+B1C (standard mode No. 2)

• advantage: the same as option 5 GPS+GLONASS, but catches more satellites (mode for cities with tall buildings).
• disadvantage: satellites do not participate in determining B1C coordinates, i.e. as if they were spare ones in case of poor sky visibility.

14 - GLONASS+BD2+B1C
doesn't work

15, 16 and 17 - not tested.

18 - BD2 + Galileo

• advantage: works
• disadvantage: loses satellites.

19 - GPS+BD2+Galileo (standard mode No. 1)

• advantage: works, high accuracy of coordinate determination: 4 meters.
• disadvantage: the same as point 3: it takes a long time to register - 120 seconds, often Galileo E1 satellites do not participate (because there are few of them in the sky)

20 - GLONASS+Galileo

• advantage: works
  *disadvantage: very long stay of satellites 319 seconds, low accuracy of 15 meters.

21 - GPS+GLONASS+Galileo (standard mode No. 4)

• advantage: the same as point 5 (confident and quick finding of satellites and determination of coordinates)
  *disadvantage: none.

22 - BD2+GLONASS+Galileo
doesn't work

23 - not tested.

24 - B1C+Galileo

• advantage: looking for companions.
• disadvantage: does not find them.

25 - GPS+B1C+Galileo (standard mode No. 3)

• advantage: fairly fast search of 66 seconds and high accuracy of 5m, the smartphone keeps the satellites stable.
• disadvantage: there are options with faster search - items 5, 13, 21, which include GLONASS.

26 - BD2+B1C+Galileo
doesn't work

27 - not tested

28 - GLONASS+B1C+Galileo
doesn't work

29 - GPS+GLONASS+B1C+Galileo
Doesn't work on my phone. In other smartphones with a Unisoc processor, searching for satellites takes a long time.

2.2 Conclusion: optimal options for satellite positioning systems for search speed

1) GPS+GLONASS+Galileo (standard mode No. 4 = number 21 in Custom Mode)
2) GPS+GLONASS+B1C (standard mode No. 2 = number 13 in Custom Mode)
3) GPS+B1C+Galileo (standard option No. 3 = number 25 in Custom Mode)
4) GPS+BD2+Galileo (standard mode No. 1 = number 19 in Custom Mode)

For weak smartphones, we can recommend the option of two systems:
5) GPS+GLONASS (number 5 in Custom Mode).

gps-glonass.png - GPS+GLONASS

GLONASS+BD2:

GPS+GLONASS+BeiDou_B1C:

GPS+GLONASS+Galileo: [/columns]

Illustrations: Free:
www.vecteezy.com - orbital-satellite-icon
www.magnific.com - gps-location-car-service

Source: https://cardvd.ru/problemy-s-gps (page now 404 - deleted).