This guide covers two things: how to obtain a high-accuracy coordinate for your local base station, and how to add that base station to a capture inside the Looq app once you're ready to process. For general best practices on base placement, sky visibility, and RINEX file requirements, see Base Station Field Setup: Tips & Tricks - Looq.ai.

Step 1: Get an Accurate Coordinate for Your Base Station

Before you can use a local base station in Looq, you need its true, high-accuracy coordinate. This is the single most important input for absolute accuracy — if the base coordinate is wrong, every point in your processed dataset will be shifted by the same amount.

Do not use the following to determine your base coordinate:

• Google Earth or any satellite-imagery-based coordinate lookup
• Your cellphone's built-in GPS
• Any consumer-grade or navigation-grade device

These sources are only accurate to several meters at best, which is far outside what's usable for survey-grade processing. Looq needs a coordinate accurate to the centimeter level.

There are two acceptable ways to get an accurate coordinate:

Option A: Submit Your Base File to a PPP Processing Service

If you don't have a known, published point to set up over, you can log your base station on an arbitrary stable point and then send the raw observation file to a free or paid PPP (Precise Point Positioning) service, such as:

• NRCan's CSRS-PPP (The service is free, but you will need to register here: Sign in)
• NGS OPUS (OPUS: the Online Positioning User Service, process your GNSS data in the National Spatial Reference System)
• AUSPOS (AUSPOS - Online GPS Processing Service | Geoscience Australia)

These services process your base file against global reference networks and return a precise coordinate for where your antenna was actually located — typically accurate to a few centimeters. Once you have that coordinate, it becomes the value you'll enter for your base station in Looq.

Note: The PPP service's coordinate output already accounts for your antenna height, since the height was included in the file you submitted. This means the height correction is already resolved before you bring the coordinate into Looq — you don't need to re-apply it there.

Option B: Set Up Over a Known Point

If you have access to a monument, benchmark, or survey point with previously published, high-accuracy coordinates, you can set your base station up directly over that point. As long as the point's published coordinates are accurate and you're confident in your setup (centering and antenna height), you can use those coordinates directly, or use your own survey software to process and confirm them.

Either way — PPP output, a known monument, or your own processing software — the coordinate you bring into Looq must come from a high-accuracy source. Anything else will introduce an offset into your entire dataset.

Step 2: Add the Local Base Station to a Capture in Looq

Once you have your high-accuracy base coordinate ready (or your PPP-processed RINEX file), you can attach the base station to your capture.

1. Wait for the capture to appear in your notifications after it has finished uploading.

   

2. Create a new site (New Site - Looq.ai), or add the capture to an existing site.
3. In the "Start Processing for Capture" window, select "Local Base." 

   

4. Click "Add Base Station" if you do not have one already imported. If you do, you can select it from the drop down menu. 

   

    

5. In the Add Base Station window:
   • Name the base station (use something identifiable — site name, date, or point ID works well if you'll be reusing this base later).
   • Upload your RINEX observation file for the base station. 

     

6. Choose how you want to provide the base coordinate:
   • Use the RINEX header — if the header coordinate already reflects a high-accuracy source (for example, it was written in by your receiver after PPP processing, or the file came from a CORS/vendor network with a published, accurate position).
   • Manually enter the coordinates — if you're supplying the coordinate yourself from a PPP result, a known point, or your own processing software. 

     

A Note on Antenna Height

If your coordinate came from a PPP service, the antenna height was already included in the file you submitted, and the PPP-derived coordinate reflects the true ground/monument position — not the antenna's phase center. That means the height error has already been resolved before the coordinate reaches the Looq app, and you don't need to enter or adjust for antenna height again during this step.

If the RINEX Header and Manually Entered Coordinates Don't Match

Some receivers write a coordinate into the RINEX header automatically — often an autonomous, low-accuracy position rather than a true surveyed one. If you choose to manually enter coordinates instead of using the header, it's possible for the two values to disagree, sometimes by a significant amount.

To avoid confusion or an incorrect result:

• Always confirm which coordinate you intend Looq to use before starting processing. Don't assume the app will automatically prefer the more accurate value.
• Double-check your entry against your source (PPP report, known point record, or your own processing output) any time you manually enter coordinates, rather than relying on the RINEX header being correct by default.
• If you're not sure which value the app is using, treat this as a step worth confirming with your processing lead or by cross-checking the result against your known base coordinate — a mismatch here can shift your entire dataset.
• When in doubt, manually entering the coordinate from your high-accuracy source is the safer choice, since header values are not guaranteed to reflect survey-grade accuracy.

Base Station Time Coverage Requirement

Your base station must be logging for the entire duration of the qCam capture, with a buffer on both ends:

• Start the base station recording at least 5 minutes before the qCam capture begins.
• Keep the base station recording for at least 5 minutes after the qCam capture ends.

This buffer ensures there's overlapping data at the very start and end of the capture window, which the processing needs to resolve corrections cleanly across the full capture — not just the middle portion. If the base station's recording window is shorter than the capture (or doesn't fully contain it), the processing may fail or produce degraded accuracy at the edges of your dataset.

Before you leave the site: confirm the base station was started before the qCam and is still running after it — don't rely on memory. If you're logging capture start/end times, log the base's start/end times alongside them.

Quick Reference