2078 Chaitra · 4 marks

Numerical: FDMA channels (12.5 MHz)

Short answer

Using N = (B_t - 2B_guard)/B_c with 12.5 MHz total, 10 kHz guard at each edge, and 30 kHz channels gives N = (12,500 - 20)/30 = 416 channels.

If total bandwidth is 12.5 MHz, guard bandwidth is 10 KHz and channel bandwidth is 30 KHz, find the number of channels available in an FDMA system.

In FDMA the total band is split into equal channels, with a guard band at each edge of the allocated spectrum.

N = (B_t − 2·B_guard) / B_c
  = (12.5 MHz − 2 × 10 kHz) / 30 kHz
  = (12 500 − 20) kHz / 30 kHz
  = 12 480 / 30
  = 416

where B_t = 12.5 MHz total bandwidth, B_guard = 10 kHz, B_c = 30 kHz.

This is the classic AMPS case: each operator in the US had 12.5 MHz in each direction, giving 416 simplex channels each way (416 duplex channel pairs).

Answer: 416 channels

✓ Answer checked by Claude Opus 5.5 (high effort)

Numerical: FDMA channels (12.8 MHz) · Wireless Communication, chapter 7 · asked 2×
Non-linear effect in FDMA; channels numerical · Wireless Communication, chapter 7
Numerical: 12-cell system capacity at 2% GOS · Wireless Communication, chapter 2
FM numerical: 10 kHz baseband, 100 MHz carrier, 75 kHz deviation · Communication Systems, chapter 3
FDM bandwidth for 10 voice channels · Data Communication, chapter 6
FM numerical: 5cos(18849.55t), 9 kHz/V, 25 V, 88.7 MHz (five parts) · Communication Systems, chapter 3 · asked 3×
FM numerical: 102.4 MHz carrier, 75 kHz deviation · Communication Systems, chapter 3

All Wireless Communication chapter 7 questions →

Numerical: FDMA channels (12.5 MHz)

Related questions