Improving Quality for Onocoy Through Receiver Settings
The Onocoy quality scale is influenced not only by antenna placement but also by various receiver characteristics. While antenna positioning, multipath effects, Axial Ratio, and other RF-related factors are covered in detail in our blog, this section focuses on the simpler adjustments—receiver settings. For deeper context, we recommend reading the “Quality Scale” section in the Onocoy documentation.
Board Design
Poor PCB design can significantly degrade performance. Fortunately, this is rare and typically limited to DIY projects or boards from unknown manufacturers. So far, none of Onocoy’s partners have supplied poor-quality boards. For DIY builds, it’s recommended to carefully inspect the quality of the trace leading to the antenna input, and to check for possible interference entering via the antenna input or receiver power supply—especially noise from the processor or its clock circuitry.
Receiver Type
This plays a crucial role in performance. It’s not only about the number of satellite systems or signal bands supported. Onocoy’s Phase RMS scale directly correlates with the receiver's ADC resolution. Firmware updates can add signal support, but cannot change ADC bit depth.
Receiver Options
Septentrio refers to them as Permissions, while uBlox calls them Fuses. These are feature sets configured at the time of sale. For example, a cheap board with a Mosaic-X5 chip may lack base station mode. Always verify available permissions before purchase.
Receiver Firmware
Firmware can have a minor or major impact. It might enable new signals, fix bugs, or add features. Minimum and recommended versions are listed in “Checking the Receiver Firmware Version”. It's highly recommended to use the latest firmware, especially for Mosaic X5 and Bynav M10/M20, where firmware has significant influence.
Signal Support
Many base stations aren’t fully configured for CORS-level output. Surveying stations often limit signal output to save bandwidth, and the Mosaic-X5 is similarly conservative by default. Enable all signals using the commands:
setSignalTracking, all
setRTCMv3Formatting, 1, all
This can improve the quality score by as much as 0.200. One Onocoy partner failed to apply both commands, which led to severely degraded scores. If you hear claims that Mosaic-X5 is worse than UM980, it's likely due to incomplete configuration.
SBAS Signals
SBAS corrections are not considered by Onocoy, so on many receivers it’s sufficient to simply disable SBAS corrections. However, the Mosaic-X5 receiver has only 62 channels, and SBAS satellites can occupy up to 9 of them, which significantly limits the number of tracked satellites. Therefore, on the Mosaic-X5, it’s recommended to use the command setSatelliteTracking, -SBAS to disable SBAS satellites. On the Unicore UM980 receiver, we use the command CONFIG SBAS DISABLE for the same purpose
GPS L5 Signal
Until at least 24 GPS satellites transmitting the L5 signal are fully deployed in orbit (expected around 2027), this signal is typically marked as “unhealthy.” Single-frequency receivers relying solely on L5 will perform poorly. However, Onocoy still considers this signal valid in multi-frequency configurations.
Some receivers offer specific settings to enable or disable the use of the L5 signal. One Onocoy partner recommends enabling GPS L5 on Mosaic X5 using:
setHealthMask, Tracking, off
However, with the latest Mosaic X5 firmware, this step is unnecessary.
Unhealthy Satellites
Mosaic-X5’s setHealthMask, Tracking, off enables tracking of “unhealthy” satellites/signals. Onocoy excludes these from the quality score but includes them in “Sky Visibility” and “Code RMS” graphs. To avoid skewed metrics, disable Beidou-3 experimental satellites with:
setSatelliteTracking, -C31-C56-C57-C58
Dynamics Mode
Surprisingly, not all receivers automatically adjust their dynamic behavior—such as tightening code and phase tracking loops—when set to base station mode or assigned fixed coordinates. In the Mosaic X5 receiver, this behavior must be configured explicitly using the following command:
- setReceiverDynamics, Low, Static
This improves “Code RMS” and “Phase RMS”."
Multipath Mitigation
Multipath is one of the key factors that reduces a station’s reward by degrading the “Code RMS” and “Phase RMS” metrics. In Mosaic X5 receivers, the APME+ multipath mitigation technology is enabled by default. While effective, this feature may introduce a small amount of noise. For base stations with an excellent antenna placement—clear of reflective surfaces—you can disable this function using:
setMultipathMitigation, off, off
Unicore UM980 receivers feature a similar multipath mitigation system, which can be enabled with::
CONFIG MMP ENABLE
As with the Mosaic X5, this function can also be disabled in high-quality installations to reduce any unnecessary processing
Code Smoothing Using Carrier Phase
This improves the Code RMS metric. On Mosaic X5, we currently apply:
setSmoothingInterval, all, 60, 60
But using:
setSmoothingInterval, all, 300, 30
may yield better results. For other receivers, this function is planned to be implemented via software in future versions of ELT_RTKBase
Measurement Resync
Disabling this slightly improves measurement quality on UM980:
CONFIG RTCMCLOCKOFFSET DISABLE
Elevation Mask
One limitation of the Mosaic X5 receiver is its relatively small number of tracking channels. To prevent satellites from competing for limited channels, we reduce the elevation mask using the command:
- setElevationMask, Tracking, 5
This setting filters out low-elevation satellites, prioritizing those with higher elevation angles. If your receiver has enough available channels, you can lower the elevation mask to 1 or even 0.
According to Onocoy information, only satellites with an elevation above 10° are considered in the quality score calculation. However, it seems that all tracked satellites are shown in the visualization. Interestingly, tests show that reducing the mask can actually increase reward scores.
For receivers with a higher number of channels, it’s recommended to set the elevation mask to 0.
Unicore UM980: MASK 0
Bynav M20: ECUTOFF 0
Signal Strength Mask
According to Onocoy, GNSS signals with an SNR below 34 are excluded from quality scoring. However, limiting the minimum SNR threshold to 32+ has been shown to increase the quality score—possibly because weak signals are excluded in some metrics but still impact others. To set an SNR mask:
Mosaic X5:
setCN0Mask, all, 32
UM980:
MASK RTCMCN0 32
Bynav M20:
SNRCUTOFF 32
In addition, it’s recommended to raise the threshold for GLONASS signals on the Unicore UM980 to 36+, since weak GLONASS signals tend to degrade both the “Code RMS” and “Phase RMS” metrics. For this, use:
MASK RTCMCN0 36 GLO
Whether the Mosaic X5 would also benefit from a similar adjustment is currently unknown.
Credits
These recommendations are informed by documentation from ArduSimple and SparkFun. If you use this guide, please credit our efforts.
