Back in July, I got an RCA DTC-100 (real cheap), but the nearest DTV station then was 70 miles away. Recently, two stations within 50 miles have begun onair DTV testing and I can receive them sometimes late at night with a rooftop CM 4248. During the day and at other times when I can't receive the stations, the DTC-100 shows a fluctuating signal strength within the 22 to 25 or 30 to 35 range. What do these strength values mean on the DTC-100? S/N rations, percentage of maximum possible value, or what? When the strength reaches 45 to 50 the picture begin to display.