A verification system that injects a inaudible identification code into a broadcast advertisement immediately prior to its radio frequency transmission is disclosed. An amplitude modulated sample sequence called a "digital artifact" containing, for example, a date and time code, is generated and inserted into the audio or video or composite audio and video data stream called a content "carrier." The combined data signal is converted from a digital stream to an analog signal and processed by standard broadcast transmission and transmitted in the radio frequency spectrum in the conventional manner. A radio frequency spectrum radio or television receiver receives the broadcast signal and converts to a digital data stream. A decoder processes the transmitted content carrier and extracts the digital artifact from the data stream. The derived information is evaluated, quantified, and transmitted to a central control point where it is compared with original reference and identification data.