Nearly six million people with digital receivers may still lose TV signals when digital-only broadcasts begin next February, a new study says.

The study by Centris, a market research firm in Los Angeles, found gaps in broadcast signals that may leave an estimated 5.9 million TV sets unable to receive as many channels as they did before the changeover. It may affect even those who bought the government-approved converter boxes or a new digital TV. To keep broadcast reception, many viewers may have to buy new outdoor antennas, the study found.

The Centris study predicts greater disruption of service than government agencies like the Federal Communications Commission have acknowledged.

The federal government estimates that 21 million American households have primary TV sets that receive only over-the-air signals. But it says most will continue to get a digital signal by means of a digital-to-analog converter box, which costs about $50 to $70. It is helping to underwrite the cost of a converter box by issuing $40 coupons.