STM32DUİNO WİTH GPS

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mrburnette
Posts: 633
Joined: Thu Dec 19, 2019 1:23 am
Answers: 7

Re: STM32DUİNO WİTH GPS

Post by mrburnette »

ag123 wrote: Sat Sep 11, 2021 9:45 pm ...
In addition, GPS is normally 'quiet' unless it 'sees' satellites in the open sky. If they aren't there, maybe it'd just remain silent.
A new GPS that has never been powered-on may take many hours to work out the satellite constellation before sending valid NMEA (some units "jaber" garbage, some output nothing.) This is especially true for older GPS modules like NEO-6. Really, it is a rather complex math problem and proprietary algorithms are utilized to accelerate the "lock".
https://www.math.tamu.edu/~dallen/physics/gps/gps.htm

In testing in my lab in the 2015'ish time, I noted that after a successful "lock" and valid Lat/Lon data, the GPS could be off for several days and reestablish lock within about 15-20 minutes. I have a NEO-6 clock built around 2015 and it has been keeping perfect time year-on-year even though it is located in a basement office with no windows... Remarkable technology. Originally it used an Arduino mini and it was refurbished with a Maple Mini clone.

For first-time power-on, make certain that the GPS module has a very open view of the sky. The more satellites seen, the faster the sync process occurs.
1.2 Time mode
The following modes are available with LEA-6T modules.
1.2.1 Survey-in
If the position is known, the receiver can provide an accurate time solution by tracking only one satellite. For an
unknown position, the receiver needs a minimum of four satellites to calculate a position fix and to solve for a
timing solution. This is known as survey-in and can be chosen using the UBX-CFG-TMODE2 message.
It is recommended to use survey-in only for non-moving platform applications. For optimal performance
a known fixed position of the antenna should be used.
ag123
Posts: 1655
Joined: Thu Dec 19, 2019 5:30 am
Answers: 24

Re: STM32DUİNO WİTH GPS

Post by ag123 »

My 'android' phone GPS is apparently very sensitive, it gets a fix even indoors.
But accordingly GPS signals is below the noise floor of today's very noisy open radio waves environment congested by all that common radio signals today, Wi-Fi, phones, Bluetooth etc, GPS signals is possibly closer to the thermal noise floor. The GPS technology itself is already advanced prior this age, consider that the signals are around or below the thermal noise floor even without other interfering signals.

What I read somewhere once is, GPS requires a modestly good antenna and being exposed to a vast stretch of open sky. It takes 3-4 satellites to get a fix. Using a good antenna for GPS can possibly allow an indoor fix
hobbya
Posts: 49
Joined: Thu Dec 19, 2019 3:27 pm
Answers: 1

Re: STM32DUİNO WİTH GPS

Post by hobbya »

The cell phone downloads the ephemeris/timing information from the server to get the predicated orbits of the satellites. By this approach it no longer needs to acquire/search the satellites. It just need to do tracking according to the prediction. The difference of acquisition/tracking sensitivity can be 10~20dB so you can still get a fix indoors.
Kenjutsu
Posts: 27
Joined: Tue Apr 07, 2020 10:58 am
Answers: 2

Re: STM32DUİNO WİTH GPS

Post by Kenjutsu »

A while back I started a small project using a BluePill and a NEO-6M GPS module to display info on two SSD1306 I2C displays.

I connected the GPS module to the Serial2 hardware serial port of the BP. I am using the Official Core 2.0.0. and the TinyGPSPlus library

My Arduino settings are as follows:

ArduinoSettingsF103.png
ArduinoSettingsF103.png (69.4 KiB) Viewed 1529 times

I have attached a small test program to get the data from the GPS and display it on one I2C display and the serial port, just a quick and dirty working example. ;)

BP_TinyGPSPlus_SSD1306.zip
(1.83 KiB) Downloaded 155 times
Pieter

OSX: 11.6.8
Arduino IDE: 1.8.19
PlatformIO: 6.1.4
STM32 Core: 2.3.0
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