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Table 1 Table of notations

From: High precision hybrid RF and ultrasonic chirp-based ranging for low-power IoT nodes

Notation Description
Δftx Frequency swing of the transmitted audio chirp, nominal chirp bandwidth.
Δfrx,x Frequency swing of the recorded audio chirp at mobile node x.
Λ linear increasing and decreasing triangle function.
τrx Awake time of the receiving mobile nodes.
τtx Audio signal broadcast duration of the transmitting beacon.
τ − 3 dB bandwidth of the cardinal sine.
A Amplitude of the rectangle window function.
f0 Carrier frequency of the transmitted audio chirp at the beacon.
mRF(t) RF signal to wake up the mobile nodes simultaneously.
ma(t) Audio signal broadcast by the beacon.
sc,sc〉(t) Autocorrelation result of the linear chirps.
TA Wake up time of the mobile nodes.
T0 Starting time of the audio signal broadcast.
vs Speed of sound (340 m/s).
xz Distance between the beacon and mobile node z.