Duplex
Understanding Duplex
Full duplex operation requires isolation between transmit and receive paths, typically achieved using diplexers, circulators, or separate antennas. Frequency Division Duplex (FDD) uses different frequencies for uplink and downlink, while Time Division Duplex (TDD) alternates between transmit and receive on the same frequency.
The duplex spacing in FDD systems must be sufficient to allow the diplexer to provide adequate isolation, preventing transmitter noise from desensitizing the receiver. Typical duplex spacing ranges from 20 MHz to several hundred MHz.
Frequently Asked Questions
What is the difference between FDD and TDD?
FDD uses separate frequencies for uplink and downlink simultaneously, while TDD uses the same frequency but alternates between transmit and receive in time.
What is duplex isolation?
Duplex isolation is the attenuation between the transmit and receive ports of a duplexer, typically 50-80 dB, preventing the transmitter from interfering with the receiver.