GPS and GNSS in embedded systems: modules, NMEA and accuracy

GNSS looks simple when a module returns latitude and longitude. It becomes engineering when the product has to work outdoors, indoors, in motion and for years.

This is an English DEV.to draft based on a Silicon LogiX technical article. The canonical source is linked at the end.

Why it matters

Positioning is a system problem. The receiver, antenna, firmware parser, power budget and mechanical enclosure all affect accuracy.

A robust design must consider fix time, multipath, sky visibility, interference and the required confidence level.

Architecture notes

• Most modules expose NMEA 0183 over UART, which is easy to parse but verbose and not always ideal for high-rate data.
• Binary protocols can provide better control over constellations, update rate, power modes and diagnostics.
• A-GNSS, SBAS, DGPS and RTK solve different problems. They are not interchangeable accuracy labels.
• Timing applications care about PPS stability as much as geographic position.

Practical checklist

• [ ] Choose antenna type and placement before freezing the enclosure.
• [ ] Log raw fix quality: satellites, HDOP, fix type, time to first fix and signal level.
• [ ] Validate behavior in the real environment, not only on a desk near a window.
• [ ] Use a non-blocking parser and handle partial or corrupted sentences.
• [ ] Budget power for acquisition peaks and backup supply if fast reacquisition matters.

Common mistakes

• Testing only in open sky and then deploying in urban or industrial environments.
• Assuming latitude and longitude are enough without quality metadata.
• Ignoring antenna ground plane and cable losses.

Final takeaway

GNSS integration is easy to prototype and easy to underestimate. Production quality comes from diagnostics, RF awareness and realistic field testing.

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Canonical source: GPS and GNSS in embedded systems: modules, NMEA and accuracy

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