If both scanners are being used in a stationary environment, like at home, program in only one site at at time in your surrounding area. Give it a day or so, monitor the reception, once you're satisfied with the results, remove that site's programming and try another and so on until you find which site(s) give you the best reception and go from there. If you're mobile, then I would apply what Tvengr mentioned above. Also, try different locations around the house, different antennas or an outside antenna with a solid length of cable: RG6 or better. Don't use RG58/59 for distances over 6 or so feet to the antenna. It's going to take some trial and error to get the results you want.