Timeline for GPS taking long time to fix out in the open
Current License: CC BY-SA 4.0
16 events
| when toggle format | what | by | license | comment | |
|---|---|---|---|---|---|
| Sep 9, 2020 at 15:00 | history | tweeted | twitter.com/StackElectronix/status/1303709779102183431 | ||
| Sep 4, 2020 at 22:21 | comment | added | Swapnil Saha | The reason I chose this chip is because it's one of the smallest GPS modules with integrated antenna and consumes low power. | |
| Sep 4, 2020 at 22:21 | comment | added | Swapnil Saha | I designed my own PCB keeping these issues in mind. I will see if mine makes any difference but I doubt it will improve the performance. | |
| Sep 4, 2020 at 22:13 | comment | added | le_top | While it's an old module with IMHO a not so good chip, the host board could clearly be better as well. To check if the capacitors have an influence, I might have moved their location on the PCB, but it's difficult to do by hand here. The antipad seems to be missing (there seems to be a via there), the top ground area under the module should have been "separate" but seems joined with the top GND ("Avoid copper pour on the module side, keeping out the module minimum 3mm from the copper planes", "Decoupling capacitors might be placed in the keep out area as close as possible to the VCC pad.) | |
| Sep 4, 2020 at 21:59 | comment | added | le_top | Ok, I didn't notice this was a Module from Origin on a breakout. Already from 2014. It haseverything on board "Fully integrating: Low profile antenna element, Dual-stage LNA, SAW filter, TCXO, RTC crystal, GPS SoC, PMU, RF shield" and is based on a SiRFstarIV, something I haven't been a fan off. Host PCB recommendations are here: origingps.com/wp-content/uploads/2018/08/… . The decoupling capacitors on pin 4 near PWR have a poor GND return path and should have been connected directly to pin 5 without via. | |
| Sep 4, 2020 at 20:29 | comment | added | Swapnil Saha | Then it's the problem with the GPS module Origin designed itself instead of breakout manufacturers and us designing PCBs. I used other cheap GPS boards earlier which did not have such long subsequent cold starts. If they had properly designed the module properly then it wouldn't have issues. | |
| Sep 3, 2020 at 20:53 | comment | added | le_top | I tend to support Origin's feedback. The performance of a GPS greatly depends on the oscillator, and also on the RF input chain. The board should have a goot TCXO to start with. The required information is sent every 18 seconds, so if the first second is missed, the end of the following message is 35 seconds later. This delay is therefore achievable with Cold Start (no almanac, no known time, ...) if the GPS is well designed. Some GPS chips/modules are better than others and will still perform well even with a bad design. A battery backup helps, but you'll not notice with a good GPS. | |
| Sep 3, 2020 at 18:12 | comment | added | Swapnil Saha | Tech support was pointing out at non-plausible solutions (e.g. boards being sold in the market using their GPS module being improperly designed etc etc). The comment below provides more plausible answer. | |
| Sep 3, 2020 at 17:43 | comment | added | user57037 | Origin tech support should be able to help. | |
| Sep 3, 2020 at 16:45 | vote | accept | Swapnil Saha | ||
| Sep 3, 2020 at 16:26 | comment | added | Jörg W Mittag | It's obvious that every fix is a "first fix". The problem then points to the saved data from the first fix being lost. | |
| Sep 3, 2020 at 12:20 | history | became hot network question | |||
| Sep 3, 2020 at 9:46 | review | Close votes | |||
| Sep 9, 2020 at 3:09 | |||||
| Sep 3, 2020 at 7:54 | answer | added | Marko Buršič | timeline score: 26 | |
| Sep 3, 2020 at 5:05 | answer | added | tlfong01 | timeline score: 15 | |
| Sep 3, 2020 at 4:19 | history | asked | Swapnil Saha | CC BY-SA 4.0 |