A system for monitoring cellular communications including a passive sensor device, processors, and memory devices. The memory devices having instructions that cause the processors to identify active downlink channels using a first radio to monitor each channel in a cellular spectrum and store downlink channel information, including configuration data, for each of the identified active downlink channels. The processors identify active uplink channels using a second radio to monitor each channel in the cellular spectrum and store uplink channel information for each of the identified active uplink channels. The processors correlate one of the active uplink channels with a corresponding active downlink channel and tune a third radio to the active uplink channel using the configuration data for the corresponding active downlink channel. The processors also tune a fourth radio to the active downlink channel corresponding to the at least one active uplink channel using the corresponding configuration data.