image unclear on my cb radio?

Hi, when i turn on my CB in my Jeep all i hear is mad static, which is probably becuase noone is on that channel. but the times when i can hear ppl talking i cannot tell what they are saying due to mad static. i heard somewhere that you need to calibrate your antennae and radio to make the image clearer, also the squelch-gain dial doesnt help much at all either. ive got a cobra dx iv. just wondering what you guy think about this and if you have any helpful hint. p.s. i dont think my radio was vcalibrated i bought ther car used and it came with it. thanks! ( my antenna is set about 2 feet above the top of my car