Raw Messaging w/ L2 and nav data

Q&A forumCategory: QuestionsRaw Messaging w/ L2 and nav data
K2Logics asked 10 months ago

Hello…I almost exclusively do PPK work against U.S. CORS stations. 
I have the F9 up and running on a custom RPi 2 data logger I built.  I am successfully getting raw data into a ubx file, however, I am not getting any nav data or L2 data. 
Before I log the receiver on the RPi, I configure in U-center and have RWM-RAWX and SBRFX going out over USB.  I also have NMEA turned off when I go the RPi (and not using U-center any longer).  I can see nav and L2 signals in Receiver Manager, btw when running in U-center. 
Scratching my head on what I am missing here.  Firmware update to allow L2 output, perhaps?

goingup2000 replied 8 months ago

i am new to this rpi stuff and a jump start would be great to get me going in the right direction – i am really excited about this new board that ardusimple is coming out with the timestamp built into the board – i am looking a the zero w as the recording platform for a light weight version and the pi3 b+ for the base configuration and have been told that both platforms perform similarly. any info that you can provide would be excellent – i found this really great document here and thought i could share it just in case you were still tweeking your layout

http://www.denshi.e.kaiyodai.ac.jp/gnss_tutor/pdf/kit_01.pdf

thanks again

mike s

K2Logics replied 8 months ago

I may good use of that guide. Some more information here:

https://rtklibexplorer.wordpress.com/2016/11/04/pi-zero-based-gps-data-logger/

It is a fairly straightforward build if you follow those tow sources. Best to jump right in. I used a water tight box found here:

https://www.amazon.com/gp/product/B005UPAN0W/ref=oh_aui_search_asin_title?ie=UTF8&psc=1

I mounted pi and screen to the underside of the lid.

The gps unit, antenna jack and battery went in the base.

Battery:
https://www.amazon.com/gp/product/B078S6LH8L/ref=oh_aui_search_asin_title?ie=UTF8&psc=1

And for external charging, I cut the cord and re-soldered a usb connection to this guy:
https://www.amazon.com/gp/product/B01N66N1JK/ref=oh_aui_search_asin_title?ie=UTF8&psc=1

You’ll need an SMA jumper:
https://www.amazon.com/gp/product/B077BMJ8JH/ref=oh_aui_search_asin_title?ie=UTF8&psc=1

I run my two units each with Talisman 6200’s for some pretty amazing accuracy.

Happy to help

2 Answers
K2Logics answered 10 months ago

ok, I seem to have already made a bit of progress.  I am indeed getting L2 and nav data into my ubx file.  The problem appears to be a RTKLib/RTKCONV issue.
After getting a stray NMEA message turned off, I can convert and get Rinex .obs and .nav file, however, the .obs data still has only single frequency data.
Any suggestions on how to generate a Rinex file with dual frequency data from the native ubx file would be much appreciated!
 

Jim replied 10 months ago

http://rtkexplorer.com/downloads/rtklib-code/ Use this version of RTKLIB to get dual frquency RINEX from ZED f9p .ubx files.

Jim replied 10 months ago

RTKCONV ver:demo5 b31 – remember to check L1 & L2 in the options

RINEX Header
3.03 OBSERVATION DATA M: Mixed RINEX VERSION / TYPE
RTKCONV demo5 b31 20190110 213218 UTC PGM / RUN BY / DATE
log: E:\DroneProject\Z9Ublox\Dec27\COM12_190110_212328.ubx COMMENT
format: u-blox COMMENT
MARKER NAME
MARKER NUMBER
MARKER TYPE
OBSERVER / AGENCY
REC # / TYPE / VERS
ANT # / TYPE
0.0000 0.0000 0.0000 APPROX POSITION XYZ
0.0000 0.0000 0.0000 ANTENNA: DELTA H/E/N
G 8 C1C L1C D1C S1C C2L L2L D2L S2L SYS / # / OBS TYPES
R 8 C1C L1C D1C S1C C2C L2C D2C S2C SYS / # / OBS TYPES
E 4 C1C L1C D1C S1C SYS / # / OBS TYPES
C 4 C2I L2I D2I S2I SYS / # / OBS TYPES

K2Logics answered 10 months ago

@ Jim – I am using the Demo 5 version and that is a must for Z9 users – thanks!
 
I am up and running now with good data and PPK solutions in RTKLib.  One important key in RTKConv is to make sure the option is set to scan for data types.  It will not grab L2 data without checking this option.