What Is a Bandwidth Cap?
The frequency spectrum contained in a signal can be observed from the signal spectrogram. The difference between the highest frequency and the lowest frequency of a signal contained in a signal, that is, the frequency range possessed by the signal, is defined as the bandwidth of the signal. Therefore, it can be said that the larger the frequency range of the signal, the wider the signal bandwidth. [1]
- 3dB bandwidth
- 3dB bandwidth usually refers to
- (1) Measurement of signal bandwidth by monitoring stations
- Since the measurement of the emission at the monitoring station is performed under actual conditions, the signal passes through a certain propagation path, and the monitoring result will be subject to fluctuations in measurement values, interference,
- The receiving equipment in the monitoring station suitable for measuring the occupied bandwidth must meet the following conditions:
- 1) The frequency characteristics in the passband are flat within the range of the measured transmission spectrum, and the fluctuation range is within ± 0.5dB;
- 2) The frequency selection performance is sufficient to distinguish out-of-band noise and interference, while the edge of the passband level introduced relative to the middle of the passband does not exceed 2dB;
- 3) In order to adapt to the possible field strength change of the measured transmission, the receiving equipment must have a good linear change to the input change of at least 60dB. ,
- When using a spectrum analyzer to determine the signal bandwidth in accordance with the "x-dB" method, the maximum hold mode of operation is required. The ideal spectrum analyzer has a high resolution, which can accurately display the spectrum of the signal under test to meet the measurement of narrowband signals. To measure the bandwidth of a wideband signal, you can use the spectrum analyzer with a complete receiver and Purpose-designed receivers are used together. Some modern spectrum analyzers include firmware functions to estimate the bandwidth occupied by the signal under test. [3]