RTK GNSS Road Test: Log and Review a Drive with KALMIX Trace

KALMIX Trace turns one RTK GNSS road test into matched NMEA, RTCM3 and application-event records that can be checked against the drive timeline. This guide shows how to log the run, confirm that the record is usable and follow solution-state or correction-link changes to the intervals worth opening next.

KALMIX Trace reads the receiver's NMEA output, connects to an NTRIP service, forwards RTCM3 corrections and saves the resulting data streams. For automotive and off-highway GNSS testing, this preserves the run as a reviewable timeline instead of relying on what someone noticed on screen while the vehicle was moving.

Record the setup before driving

The Verified workflow card above identifies the setup used for this example. Before each run, record the details that can change from one vehicle, laptop or correction session to the next so the resulting files remain reproducible.

Make the run reproducible. Capture these four groups before the vehicle moves.

Receiver

Model, firmware and NMEA output rate.

Software & host

Trace version, Windows version, COM port, baud rate, local clock, time zone and sleep settings.

Corrections

NTRIP caster and mountpoint used. Keep credentials out of shared records.

Route & time context

Planned conditions, screen recording, forward road video and a visible synchronization cue.

Log the drive with Trace

Plan at least one open-sky baseline and the obstruction conditions that matter to the deployment. If two runs will be compared, keep route direction, speed range, correction setup and receiver configuration as consistent as practical.

1. 01

   Prepare the receiver, vehicle and laptop

   Mount the receiver securely with the best practical sky view, route the cable so vehicle movement cannot pull it loose, and prevent the laptop from sleeping during the run. Use a data-capable USB cable, confirm the assigned COM port, and check that the Windows clock and time zone are correct before starting any screen or road recording.

   

2. 02

   Enable all three logs before opening the serial port

   Select NMEA, raw RTCM3 and application-event logging before the receiver connection starts. This gives the three files one session prefix and preserves the start of the connection as well as the drive itself. Applying new Logging settings may begin a new timestamped file set, so make the selection before departure and keep all three files from the chosen session.

   

3. 03

   Open the serial port and start corrections

   Open the receiver's COM port with the configured baud rate, then start the NTRIP correction profile prepared while the vehicle is parked. Confirm that all three expected log files exist and are growing before departure. The NMEA count should keep increasing, RTCM received / forwarded should advance after the correction service connects, and correction age should be available. For the complete Windows connection sequence, see the Trace for Windows guide.

   

4. 04

   Drive the route and preserve time context

   Once the vehicle is moving, use Trace as a live health check rather than an analysis screen. Watch for continuous NMEA updates, advancing RTCM counters, correction age and changes in the receiver-reported solution state. Record the computer's local time or a visible synchronization cue, and preserve any change in the screen recording for review after the drive.

   Keep the driver focused on the road. A passenger should operate the laptop, or Trace should be left recording unattended when the driver is alone.

   

5. 05

   End the session and confirm the files

   When the vehicle is parked, disconnect the correction service, close the serial port and use Open folder to inspect the session. Confirm that the NMEA, RTCM3 and application-event files share the expected prefix and have plausible, nonzero sizes before unplugging the receiver or closing Trace.

Read the reported solution state

Trace displays the quality value reported in the GGA sentence together with a readable status. These states are useful markers in the test timeline: they show where the receiver's reported mode changed and where to begin a closer review.

Check whether the record is usable

By default, Trace writes logs to a logs folder next to KALMIX Trace.exe; if another folder was selected in Logging settings, use Open folder to open it. The Trace for Windows guide covers the complete folder and connection setup.

A usable road-test record has three matched session files, continuous GGA timestamps, a retained correction stream, and media or route notes that can be aligned to the computer's local clock. The NMEA log is the receiver's reported output; it is not a raw-observation file for post-processed positioning. Copy the originals into one test folder and keep their names unchanged. Work from copies, and remove precise coordinates, credentials or private connection details before sharing records outside the test team.

Example: turn one run into a review timeline

In this run, the first pass reduced roughly 27 minutes of driving to a small set of intervals worth opening alongside the Trace capture and road video. The figures came from the matched NMEA, RTCM3 and application-event files; displayed times use the Windows local clock. They illustrate the workflow rather than benchmark every route or receiver.

The CRC24Q result checks the integrity of the retained frames; the RTCM 3 frame and MSM reference explains the message structure behind that record.

Follow a flagged interval

A flagged interval gives the team a precise place to start. Review each longer Float or Standalone section in the same order:

1. Open the NMEA time range. Note when the state changed, how long it lasted and whether it recovered to Float or Fixed.
2. Check the correction link. Look at correction age, RTCM flow and application events for signs of an interruption or reconnect during the same period.
3. Compare the road context. Align the interval with the Trace capture, road video or route notes and look for canopy, elevated structures, tunnels or other changes in sky visibility.
4. Decide what to do with it. Keep the interval as a representative observation, exclude it if the record is incomplete or repeat the route when the project needs a cleaner comparison.

This sequence is especially useful when corrections become old or unavailable during motion. A rising or missing correction age, stalled RTCM counters and a correction-service event at the same time direct the review toward the NTRIP correction path; a state change while corrections continue to flow directs the next check toward the receiver record and road environment.

To move from a flagged interval to a scenario-level performance review, see RTK Accuracy Trap: Can a Datasheet Predict Field Performance? For a worked reference-trajectory process, use the K35E Ground Truth road-test record.

Connect the timeline to the road environment

The tree-lined-road and elevated-expressway images were aligned with longer flagged segments. The open-road image is a comparison from the same test material, but it is not assigned to a specific flagged interval. Together they show how Trace data and road context can guide the next engineering check.

Open road

The road view has a comparatively open sky, and the paired Trace capture reports RTK Fixed (4). Use it as a visual comparison for the more obstructed parts of the route, not as a performance benchmark.

Tree-lined road

This image corresponds to the long yellow RTK Float section on the trajectory. The canopy and roadside vegetation restrict the practical sky view, while Trace reports RTK Float (5). The state change is the useful marker for comparing this interval with correction availability and a later repeat run.

Beneath an elevated expressway

This image corresponds to the long blue Standalone section. The elevated structure heavily obstructs the sky view, while the paired Trace capture reports Standalone (1) and shows correction age as --. That makes this the first interval to open in the retained RTCM3 and application-event records.

Road-test logging checks

Frequently Asked Questions

Does KALMIX Trace calculate the RTK solution?

No. The connected GNSS receiver calculates and reports the position and solution state. Trace displays and records that output, manages the correction connection used in this workflow and preserves the related data streams for review.

Why record NMEA, RTCM3 and application events together?

The NMEA log provides receiver-reported positions and solution states, the RTCM3 log preserves the correction stream, and application events mark connection or reconnect activity. Their shared session prefix lets you review the same interval across all three.

What does correction age “--” mean in Trace?

It means Trace cannot calculate a current correction-age value from the data available at that moment. Treat it as a review flag: check whether the RTCM counters are still advancing, then inspect the retained RTCM3 and application-event records before deciding whether the correction stream stopped.

A repeatable vehicle-test workflow

KALMIX Trace turns a drive into a matched set of NMEA, RTCM3 and application-event records. With the hardware secured, logging started before connection and time references preserved, the team can confirm that the run is usable, locate longer Float or Standalone sections and review them against correction-link events and the road environment.

That makes the workflow useful for connection troubleshooting, test archiving and planning the next run. For a controlled repeat, change one variable at a time—such as antenna placement, cable or host, correction path, or receiver configuration—while keeping the remaining setup stable. When the project moves from first-pass review to quantitative position validation, add an independent reference trajectory through a dedicated ground-truth method.

Receivers for this workflow

SCOUT PRO RTK+DR is the receiver verified in this road test. SCOUT is a related dual-band RTK path that uses the same Trace host interface and NMEA logging workflow.

Tested in this road test

Kalmix SCOUT PRO

The SCOUT PRO RTK+DR used for this 20 Hz vehicle logging and review example.

View SCOUT PRO →

Same Trace interface

Kalmix SCOUT

A compact dual-band RTK receiver using the same USB-C host interface and NMEA logging path.

View SCOUT →

Need quantitative position validation rather than first-pass workflow review? Continue to the K35E Ground Truth road-test record.