A detection apparatus includes a tuner tuned to the program and a meter
coupled to the tuner and arranged to detect content ancillary information
from the program tuned by the tuner. The content ancillary information
may be a media link, closed captioning information, or the like. The
meter may also be arranged to extract a broadcast signature from the
program. A comparator compares the broadcast signature to a reference
signature selected from a library of reference signatures based upon the
content ancillary information. Broadcast signatures from unknown programs
may be clustered at least partially on the basis of the content ancillary
information.