Frequency dependent group transit time distortion - in carrier-frequency channel is monitored by transmitting AM carrier during TV signal blanking period

摘要

The monitoring system is used for measuring frequency-dependent group transit-time distortion in a carrier-frequency transmission channel, and transmits a HF carrier which is amplitude modulated by a split frequency signal. The split signal is retrieved at the receiver and it is compared with a reference signal. A vestigial sideband (VSB) television signal is transmitted over the channel and the AM carrier is transmitted in the vacant lines during the vertical blanking period of the VSB television signal. The advantage of the monitoring or measuring system lies in its speed and in avoiding known problems. The split frequency reference signal is obtained by frequency division. The transmitted signal covers the band (fT-fsp) to (fT+fsp).