Phone test tool replicates city

The NIST techniques could also simulate complex real-world environments for design and test of other wireless equipment.

The researchers conducted tests in an area of Denver, Colorado, to measure precisely the clustering of signal reflections from radio waves bouncing off one or more multi-storey buildings multiple times before reaching a distant receiver.

The researchers replicated this environment indoors using a ’reverberation chamber’, a room with highly reflective surfaces and a big, slowly rotating paddle that automatically alters signal paths.

To do this, the researchers fed a wireless transmitter’s signal into a fading simulator, which is adjusted to recreate the timing and strength of the reflections of an outdoor urban area.

The output is fed into the reverberation chamber, where signal reflections decay exponentially over time, creating a cluster of signals similar to that observed in the field tests.

Industry certification of mobile phones currently requires tests of parameters such as total radiated power using the opposite of a reverberation chamber, a room called an anechoic chamber that is lined with materials that absorb radio waves and reflect as little as possible.