FCC Chairman Kevin Martin said that that the federal government underestimated the number of over-the-air homes and could run out of funds for digital TV converter box vouchers, Broadcasting & Cable reports. Martin said the current funding was based on projections that didn’t anticipate that the percentage of people who requested coupons that actually redeemed them could increase in the coming months. Martin made the claims in a letter to the House Energy & Commerce Committee, B&C says.