Abstract : This paper focuses on the application of digital satellite communication in television stations. Through discussions of indicators such as noise, gain, local oscillator frequency stability, phase, noise, and input voltage VSWR, it elucidates the selection of low-noise downconverters (LNBs). Keywords : Digital satellite receiving system, downconverter application. Television stations are increasingly using digital satellite communication. Liaoning Television, for example, broadcasts over 100 satellite live programs annually, plus recording over 10 hours of footage daily, totaling nearly 40 programs. The utilization rate of the satellite system is extremely high. Therefore, ensuring the reliability and stability of the digital satellite receiving system has become a crucial issue that engineers must carefully consider. Low-noise downconverters (LNBs) play a vital role in fully realizing the superior performance and effectiveness of satellite digital systems. Their perfect compatibility with the signal transmission characteristics of the digital system is essential to achieve optimal transmission and minimize bit error rate; therefore, selecting an LNB compatible with the system is crucial. There are approximately 50 technical indicators used to measure the quality of an LNB, such as RF leakage, out-of-band rejection, in-band noise, out-of-band noise, aging phenomena, vibration damping, corrosion resistance, connector types, anti-static properties, intermodulation, operating dynamic range, resistance to external environments, reliability, and others. Here, we will discuss a few key indicators. 1. Noise LNB noise can be interpreted as the LNB's sensitivity or its inherent noise added to the received signal. Therefore, the lower the LNB's noise, the more sensitive it is to receiving weak signals. The standard frequency range for C-band LNBs is 3.4–4.2 GHz, and noise is expressed in Kelvin (K). Kelvin is a unit of measurement related to the amount of molecular motion at a given temperature. Many people believe that Kelvin is the same as C-band noise, which is technically incorrect because Kelvin is a unit of measurement, not a temperature value. At zero Kelvin (0°K), molecular motion is completely at rest, or there is no noise present in a system. Noise levels at 15°K for C-band LNBs are already quite low; typical LNBs have noise levels above 30°K. [align=center][b]For more details, please click: Application Selection of Low-Noise Down-Inverters (LNBs)[/b][/align]