A device may include a primary antenna configured to be located external to a subject and at least one processor in electrical communication with the primary antenna. The at least one processor may be configured to cause transmission of a primary signal from the primary antenna to an implantable device, wherein the implantable device includes at least one pair of modulation electrodes. The at least one processor may be further configured to adjust one or more characteristics of the primary signal to generate a sub-modulation control signal adapted so as not to cause a neuromuscular modulation inducing current at the at least one pair of modulation electrodes when received by the implantable device and to generate a modulation control signal adapted so as to cause a neuromuscular modulation inducing current at the at least one pair of modulation electrodes when received by the implantable device.