The military expects to introduce a tablet prototype of its combat translation system by the end of the year, officials said Wednesday. Troops have depended on translators in Iraq and Afghanistan for the past decade. The Pentagon’s researching arm the Defense Advanced Research Projects Agency, has also offered translation services that allows troops to speak into a device that immediately translates the phrase for the local population. It is part of the Broad Operation Language Translation program that was intended to allow “real-time interactive translation between two people” in a range of languages.