直放站由天線、射頻雙工器、低雜訊放大器、混頻器、電調衰減器、濾波器、功率放大器等元器件或模組組成，包括上、下行兩種放大鏈路。其工作的基本原理是：用前向天線（施主天線）將基站的下行信號接收進直放機，通過低噪放大器將有用信號放大，抑制信號中的雜訊信號，提高信噪比（S/N）；再經下變頻至中頻信號，經濾波器濾波，中頻放大，再移頻上變頻至射頻，經功率放大器放大，由後向天線（重發天線）發射到移動台；同時利用後向天線接收移動台上行信號，沿相反的路徑由上行放大鏈路處理：即經過低噪放大器、下變頻器、濾波器、中放、上變頻器、功率放大器再發射到基站。從而達到基站與移動台的雙向通信。

數位直放站，主要區別與類比直放站的是在中間處理環節和中繼環節採用了數位的處理方式，數位中頻、數位濾波等技術。

The repeater consists of antennas, radio frequency duplexers, low-noise amplifiers, mixers, ESC attenuators, filters, power amplifiers and other components or modules, including uplink and downlink amplification links. The basic principle of its work is: use the forward antenna (donor antenna) to receive the downlink signal of the base station into the repeater, amplify the useful signal through the low-noise amplifier, suppress the noise signal in the signal, and improve the signal-to-noise ratio (S/ N); then down-converted to intermediate frequency signal, filtered by filter, amplified at intermediate frequency, shifted and up-converted to radio frequency, amplified by power amplifier, transmitted from the backward antenna (retransmission antenna) to the mobile station; The backward antenna receives the mobile station's uplink signal, and is processed by the uplink amplification link along the opposite path: that is, it passes through the low-noise amplifier, down-converter, filter, intermediate amplifier, up-converter, and power amplifier and then transmits to the base station. So as to achieve two-way communication between the base station and the mobile station. 

The main difference between digital repeaters and analog repeaters is that they adopt digital processing methods, digital intermediate frequency, digital filtering and other technologies in the intermediate processing link and relay link.