Digital television signal monitoring/surveillance technique having prime/secondary distribution with surveillance signal/digital signal multiplexed and distributed with up link return anomalies monitored.

摘要

The digital transmission surveillance network has a central station (STC) connected to secondary stations with down channels broadcasting digital words and up link channels broadcasting and collecting digital signals. Digital surveillance signals (SSD) are broadcast (1,2) and multiplexed with first digital word signals (TVD) towards the secondary stations, transmitting a modified signal and identification signal. The returned uplink signals are analysed (3) in the uplink channel to detect signal anomalies.