1. A system comprising: a field recorder configured to: capture content from a plurality of transmission sources during transmission of the content to users; generate a computer readable representation of the content; an end-user device configured to: receive particular content from a particular transmission source of the plurality of transmission sources; generate an output of the particular content in a human perceptible format; generate a computer readable representation of the particular content; a channel identification server coupled to the field recorder and the end-user device via a communications network, the channel identification server configured to: receive the computer readable representation of the content from the field recorder; receive the computer readable representation of the particular content from the end-user device; compare the computer readable representation of the content from the field recorder to the computer readable representation of the particular content from the end-user device to generate a comparison result; and identify the particular transmission source based on the comparison result.