  We design a custom spectrum sensing network, called RadioHound, capable of
tuning from 25 MHz to 6 GHz, which covers nearly all widely-deployed wireless
activity. We describe the system hardware and network infrastructure in detail
with a view towards driving the cost, size, and power usage of the sensors as
low as possible. The system estimates the spatial variation of radio-frequency
power from an unknown random number of sources. System performance is measured
by computing the mean square error against a simulated radio-frequency
environment. We find that the system performance depends heavily on the
deployment density of the sensors. Consequently, we derive an expression for
the sensor density as a function of environmental characteristics and
confidence in measurement quality.
