A system for automatically monitoring the programs broadcast by network affiliated broadcasting stations includes a plurality of remote monitoring sites and a central office for periodically interrogating the remote monitoring sites. Each remote monitoring site contains apparatus for monitoring time varying program identifying data, and for storing the data in a change format when the time varying data changes in an unexpected manner. An elapsed time clock in each remote monitoring unit generates a record of the elapsed time between the unexpected changes.
Each remote unit includes a minicomputer having a read-only memory and a random-access memory. The data in the read-only memory serves to establish communications with the central office and permits the central office to access the random-access memory. After the random-access memory has been accessed, it may be reprogrammed to alter the operation of the remote monitoring unit to accommodate different data formats or different information.