Motorola Atrix 4G :: Poor Signal Reception

Over the past two weeks I've tried three different Atrix phones and two different SIM cards, but I still have poor reception, especially indoors. The current signal strength readings are: -113 dB, ecno: -18, rat: 3g. At the AT&T store, which is right next to a cell tower, their demo Atrix has -52 dB signal, while mine varies between -62 dB and -88 dB. They tell me not to worry about the signal strength unless I'm dropping calls, but conversations are often unintelligible even though they're not dropped.