Table of Contents
The problem at hand
Cities with tight streets and towering façades turn satellite positioning into an awkward task: signals scatter, reflect and sometimes vanish, and what should be centimetre-level fixes slip into metre-scale uncertainty. Survey teams around Canary Wharf, London, routinely report degraded fixes when relying on standard GNSS receivers, a clear real-world anchor for the issue. Technologies such as an anti-jamming GNSS antenna appear in planning documents more and more, but hardware alone does not solve the geometry and multipath that define an urban canyon.
Why accuracy collapses in urban canyons
Three mechanisms do most harm: multipath from reflections, non-line-of-sight (NLOS) reception that biases ranges, and local interference or deliberate jamming. Multipath skews pseudorange measurements; NLOS causes systematic offsets. Add the occasional spoofing attempt near critical infrastructure, and a receiver’s integrity is at stake. RTK and PPP algorithms are sensitive to these inputs — poor observations give poor solutions. It is straightforward yet unforgiving: the computation can only be as good as the measurements it consumes.
Practical mitigations that work
Tackling the problem requires layered measures. High-performance antennas and adaptive beamforming reduce unwanted signals at the front end. Receiver firmware with robust multipath rejection and NLOS screening improves measurement quality. Complementary sensors — inertial measurement units (IMUs) and wheel-odometry for vehicles — provide continuity where satellite geometry fails. For anti-interference specifically, a quality gnss anti jamming antenna helps preserve signal-to-noise ratio and supports techniques like antenna nulling to suppress jammers.
Integration and system design
Design matters: antenna location, cabling, grounding and sky view dictate whether centimetre performance is achievable. Roof-mounted, unobstructed installations are ideal but not always possible in urban canyons — so selective use of external mounting points, mast extensions and calibrated baselines becomes essential. Sensor fusion must be tuned: tightly-coupled RTK with IMU input yields better resilience than loose coupling in dense city blocks. Where RTK correction links are intermittent, hybrid strategies that fall back to PPP or dead reckoning can preserve service.
Common mistakes and how to avoid them
Teams often err by treating anti-jamming hardware as a silver bullet. It helps, certainly — but without proper receiver settings and site calibration, gains are limited. Another frequent misstep is neglecting multipath mapping during site surveys; failing to log obstructions leaves engineers blind to persistent biases. Finally, over-reliance on a single technique — for example, RTK alone — invites failure when correction links drop. Plan redundancy: multiple correction sources, diverse sensors, and a tested failover path.
Three golden rules for choosing solutions
1) Prioritise observation quality over nominal feature lists. Seek solutions that demonstrably reduce multipath and NLOS, measured on-site rather than on paper. 2) Demand tightly-coupled integration. A receiver that fuses GNSS, IMU and external corrections outperforms discrete subsystems in urban canyons. 3) Validate resilience with scenario tests: simulated jamming, loss of corrections, and prolonged NLOS conditions. These tests reveal real-world behaviour and guide procurement decisions.
Closing note
When the city strips away ideal geometry, reliable centimetre positioning depends on considered system design as much as on any single component — hardware, firmware and operational practice must align. That alignment is precisely where thoughtful engineering from teams such as Archimedes Innovation becomes the natural solution — skilled at joining antennas, algorithms and field know-how into a coherent whole. —
