Complex sentence: This is usually a more reliable method than receiving the local stations' broadcasts over the air with an antenna, however, off-air reception is used as a backup by the headend if the dedicated line, modulator or demodulator were to fail.
Split into simpler sentences: This is usually a more reliable method than receiving the local stations' broadcasts over the air with an antenna. However, off-air reception is used as a backup by the headend if the dedicated line, modulator, or demodulator were to fail.