The logging for OPUS tutorial shows the logging interval set to 30 seconds and under Satellite Systems only GPS is checked. Would it yield better results / accuracy if the interval was set for 1 second and all of the satellite systems were checked?
In the GNSS settings, I have the positioning mode set to STATIC, all of the GNSS systems are checked, and the update rate is set to 1Hz. Do these even matter if I’m logging for OPUS?
No. Not necessarily. Opus will only take in 30 second interval Rinex Files. In other words, if you observe at one second and submit it, it will down sample to a 30 second interval. there is also a chance that it would fail based on the file size or.
Before surveying your point if it’s a planned observation, you should use
https://www.gnssplanning.com/#/settings
This will help to optimize ideal observations for the point, especially using just GPS. When starting your observation before recording, let the receiver sit for about a minute or two to gather broadcast almanac/clock info. Then start your observation.
At about 34° N latitude late in the day, most of the GPS vehicles are generally in the mid to southern sky. Of course this changes throughout the year. I’ve noticed this since the early days of the system. If you try to get a fix at these times, you’ll notice it will take longer just using GPS.
You can also look here to observe the collection data/status of the surrounding CORS
https://geodesy.noaa.gov/UFCORS/
Many times a user or OPUS selects adjoining stations not realizing that the station is not working or has bad data for whatever reason. If I’m using OPUS (not very often), I’ll check the surrounding stations and manual pick those for the processing instead of letting OPUS automatically pick. Also if you are manually picking your adjoining stations, try to use short baselines if possible.
Good point Bryan! I love that tool. I have been using that off and on for a decade.
Ok, so I clicked on the link and ended up on the Trimble GNSS Planning page. I dropped a pin on the approximate location where I placed my RS2+. The coordinates automatically populated in the Lat / Long fields. I don’t know what to enter in the height and elevation cut off fields? Is this the height above the ground that my Reach was set at? Or the elevation of the spot above sea level? My receiver rod is 2m so the RS2+ height would be 2.134m. What should I enter in the elevation cut off field? I entered the date & time I started my observation and its duration, plus my time zone. Then I hit apply.
I’m not sure how I’m supposed to use the results?
You can enter a rough position, horizontal and vertical. It doesn’t have to be that accurate.
You can play around with the settings, usually elevation cut off is 10° from the horizon. This blocks the sats that are low in the horizon from atmosphere distortion of the signals.
Once you’ve set day, time of day and location, it will give a table/graphic of sky view that shows available sats. During your time of observation, you’ll want as many sats as possible.
It’s pretty self explanatory once you play around with it.
Hi Eric,
We’ve recently tested the log with all GNSS satellites for OPUS and it doesn’t affect its output anyhow. OPUS doesn’t consider any satellite constellations other than GPS, so using the preset is recommended.
Regarding the GNSS settings, they affect the RTK calculation, not the logging. RINEX logging is configured by presets or manually, while the UBX log contains “pure” raw data without any exclusions.
Hi Eric,
Sorry for misleading you in the last paragraph of my comment above. If you disable particular satellite constellations in GNSS settings, the receiver stops tracking them at all. Hence, the raw data log won’t include their observations, even if they’re enabled in the Logging configuration.
However, other settings such as Elevation mask and SNR mask don’t affect the logging. The update rate will be the same for logging if the Full rate is selected.
