Программа работы с бытовыми навигаторами в практике геодезиста

sklimkim

Sorry for speaking English but I got here with the help of online translation ! I see you are using a SiRF receiver, me too ! Which one is it ? I have an old Globalsat BT-338 that I downgraded to FW 3.02 with Phase patch to be able to use it with RTKPost or maybe even RTKNavi. I tried to use your Kinematic2_MobileApp tool but I get no phase data although it does appear to be there when I log to raw with SiRFDemo. Am I doing somethin wrong? Thank you !

 

So where is everyone ? ;-)

Anyway thanks to chnav who pointed to the latest version of Kinematic2 here https://geodesist.ru/threads/progra...-praktike-geodezista.5101/page-26#post-452197 that is able to produce Rinex files with phase data for my BT-338.

 

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I am sorry I have answered on the other forum. Glad you're able to collect RINEX data.

What region you're working in ? Though not about logging raw data but there is a problem in SiRF Star III firmware with SBAS. Most SBAS satellites pre-set in FW are out of service and replaced with new PRNs. I made a tool for myself to replace 8 PRNs in firmware files. If you are ready for experiments then I can patch your FW. You can always flash it back to original version.

 

Thank you for your kind offer, I'm in Europe and use this FW http://gps.0xdc.ru/static/sirf/device/GlobalSat BT-338/3.2.2/fw-carrier-phase/ on my BT-338
I did notice that it was not getting a SBAS fix although it was set for that.

I was able to do some PPK with the BT-338 but get quite a lot of "fake fixes" so overall accuracy seems to be around 20cm, which is good of course ! The internal GPS solution is not very good with 6+ meters 2D RMS, should be better with SBAS active !

 

Oh and I found an old BT-359 for which I'm using http://gps.0xdc.ru/static/sirf/device/GlobalSat BT-359/fw-carrier-phase/ BT821-GSW3.2.4_3.1.00.12-SDK003P1.00a.bin

 

Oh I am in Western Europe (France) if that matters !

This is interesting, where do you get a DGPS internet feed for RTKNavi though ? I know where to get RTK Internet feeds but not for DGPS.

Also I experimented with a uBlox M8N with SBAS on/off and did not see any significant difference in horizontal accuracy, only in vertical accuracy so I'm not sure sure how RTKNavi can achieve such accuracy ?!

 

Ещё раз читаем ВНИМАТЕЛЬНО:
Code measurements at all frequencies and for all living satellite systems, the presence of the Internet and the RTCM 3 stream from the base station can significantly improve the quality of the coordinate solution for the code measurements.

 

ok, do you have an example of an internet feed that broadcasts DGPS corrections ?

 

ИНТЕРНЕТ Вам в помощь:

НАПОМНЮ - RTKLIB не поддерживает режим расчета DGPS с данными RTSM версии 2 .
RTCM-3 version (и новее) still has no correcting messages, but only observation messages.

 

Забавно, все станции из списка не передают поправки для ГЛОНАСС. RTKLIB всё же разбирает диф. коррекции GPS, но действительно не применяет их. С помощью rtknavi можно подключиться к станции и посмотреть какие значения передаются. А для реализации в RTKLIB DGPS нужно добавить всего несколько строчек кода.

 

Have you had a chance to "cook" an updated "bt-338/3.2.2/fw-carrier-phase/" firmware ? Thanks !

 

Файлы прошивок для SiRFStar III с разлоченной фазой (спасибо Alexey Illarionov) и обновлённой таблицей спутников SBAS (см. скриншоты). Ничего другого не менялось.

Москва:


Европа (Париж):


Примечания к прошивкам.
BT338... и BT821... - прошивки для моделей Bluetooth-GPS. Все прошивки взаимозаменяемы в устройствах BT-821, BT-338, BT-368, BT-359. Их особенность - залоченая скорость порта 38400 (для Bluetooth-передатчика). Её можно безболезненно прошивать в любые приёмники, включая старые PDA и смартфоны, только надо учесть что скорость залочена.
BU353... - прошивка для USB-GPS, скорость порта по-умолчанию 4800, можно менять программно. Ни в коем случае нельзя прошивать её в блутус-приёмники т.к. получится кирпич. Подходит для PDA, PNA, смартфонов, CF-карты BC-337 и т.д.

 

Thank you very much! I'm going to flash the BT-338 right away.
Is there any reason to flash 3.2.2 or 3.2.4 to BT-338 / BT-359?
When doing testing with VisualGPS (NMEA single, not post-processed) I noticed that the BT-359 with 3.2.4 showed big drifts (15 meters +) that I didn't see on the BT-338 with 3.2.2. Could have been coincidences of course.

EDIT - Success ! Locked in to SBAS 136 (cyan color in SiRFDemo) and I will now log in VisualGPS to see the improvement in the scatter plot. Thanks again !

 

So I logged data for a bit less than 2 hours and unfortunately, the "drifting" is still there with SBAS, too bad

 

Here's a comparison I did between the BT338/SS3 with SBAS and the Navilock 8002/uBlox 8 over 5+ hours. Sadly it seems the once great SS3 chipset can't really compete anymore, well it's 15 years old after all ;-) Still better when it comes to Bluetooth since there's never been a "cheap" uBlux 8 (or 6/7/9) Bluetooth GPS receiver.

 

@chnav - have you seen similar drifting with your SiRFstarIII receivers ?

 

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I actually couldn't run SBAS mode d/t EGNOS is not suitable for Russia.

Regarding your tests. The FW v3.2.4 is pretty old.
FW v3.2.5 and - especially - v3.5.0 has significant improvements comparing to v3.2.4 but there is no FW with baudrate locked to 38400 and it 100% will brick bluetooth GPS device (mismatching baudrates). I will try to port v3.5.0 for Bluetooth devices but this is not my primary task. I want to run SBAS SDCM first.

 

Thank you, good to hear that 3.2.5 and 3.5.0 had improvements. I think I have an old Globalsat USB SSIII GPS somewhere (maybe the BU353 actually), I'll see if I can find it.

 

So I found my old BU353, upgraded it to 3.5.0, activated SBAS and ran a 3 hour session in VisualGPS and...the results were very poor as seen below, far worse than with the BT-338 not sure what's going on. I'll give it another try.

 

Я сейчас изучаю прошивку 3.5.0, напишу если будут результаты. В приложении файл с описанием прошивки 3.5.0, что в ней было улучшего по сравнению с 3.2.5.

Прошивку v3.2.5 не советую использовать т.к. у неё проблемы с GPS WNRO (Week Number Roll-over). Но если понадобится - в интернете есть обновление от TomTom, в котором устранён этот недостаток.

Пока что есть такое наблюдение - приёмник Sirf с внешней антенной Trimble Thunderbolt даёт сигнал примерно на 7-8 dB выше, чем BU-353. Я думал, что чем ближе антенна к приёмнику (т.е. встроенная как у BU-353), тем лучше (((