GB/T 12857-1991

This standard specifies measurement methods for television broadcast receivers operating under signal conditions that deviate from standard broadcast parameters, such as non-standard modulation, frequency offsets, or impaired signal quality. It is applied in laboratory testing and quality evaluation contexts to assess receiver performance in real-world or adverse environments, including weak signal areas, interference-prone settings, or when using non-ideal transmission equipment. The standard ensures consistent testing procedures for manufacturers and engineers to verify receiver robustness and compliance with performance benchmarks beyond ideal broadcast conditions.