A wildlife-tracking receiver picks up frequency-modulated collar transmitters with…

PHYSICS · Subjective · Fermi University Physics · Electronics, Instrumentation & Communication · Communication systems and RF engineering · Communication systems and RF engineering

Electronics for Measurement, Ch Modulation, receivers and the link that carries the measurement

Problem

A wildlife-tracking receiver picks up frequency-modulated collar transmitters with peak deviation

f_{\rm dev}=3\,\mathrm{kHz}

and modulating frequency up to

f_m=1\,\mathrm{kHz}

; every collar transmits the same power with the same antenna gains, into free space with no other loss. The receiver's noise figure is

\mathrm{NF}=6\,\mathrm{dB}

referred to

T_0=290\,\mathrm{K}

, and its noise-equivalent bandwidth equals the Carson-rule transmitted bandwidth. A wanted collar

50\,\mathrm{km}

away produces a received power of

-102\,\mathrm{dBm}

. A second collar, from an animal that has wandered to within

5\,\mathrm{km}

of the receiver, transmits in the next frequency channel. Estimate how many decibels of adjacent-channel rejection the receiver's filter must provide so that the near collar's signal falls below the noise floor.

Browse the problem library