@Keith Bryant yeah urban canyons are genuinely the hardest test for any GNSS module, and you're right that cheaper single-constellation receivers basically give up in that environment — they're locked to GPS only, so when half the sky is blocked by buildings you might have 3-4 satellites visible and the geometry is terrible.
The MultiNav Pro+ handles this better than most at this price point because it's multi-constellation — pulling from GPS, GLONASS, Galileo, and BeiDou simultaneously. In a narrow street where a GPS bird is blocked to the east, there's often a GLONASS or Galileo satellite at a different orbital angle that fills the gap. More satellites from more directions means the position solution stays more stable even when your sky view is cut to 30-40%.
That said, I won't pretend any module is magic in a genuine urban canyon. You'll still see some accuracy degradation — 1.5m open sky might become 4-8m in a really tight corridor, and multipath (signals bouncing off building faces before hitting the antenna) is something no receiver fully eliminates. The 18Hz fix rate actually helps here though, because it means position errors tend to be short-lived spikes rather than long stretches of bad data — your tracking algorithm can smooth over them more easily.
For a bike tracker specifically, pairing the GNSS data with the onboard accelerometer and gyro from the Sensors Module would help a lot in dead zones — you get IMU-assisted position bridging when satellite geometry goes bad, which is basically what automotive-grade navigation chips do. Worth considering if you want robust city performance.
