Frequency Modulation
Frequency modulation, or FM, is an analog modulation scheme that encodes information by changing the frequency of a carrier wave.
FM is commonly used in
- FM Radio stations to transmit music and speech
- Pager standards such as POCSAG
- Weather satellites sending pictures using Automatic Picture Transmission (APT)
- Handheld radio transceivers using Narrow FM (NFM)
Implementation in Python
import math
RATE = 32_000
# Phase accumulator
ph = 0
for s in samples:
ph += 2 * math.pi * s / RATE
i = math.sin(ph)
q = math.cos(ph)
write(i, q)