A wheelchair clamp connects together a pair of wheelchairs situated side by side so that one attendant can move two wheelchair patients at the same time. The method may include transmitting a location data item identifying a location of an alerting apparatus to a remote server. The to-be-set switches are determined by starting with the first switch as a preceding switch, identifying the next switch for a path by simply changing the level number of a preceding switch in the path, and by changing a bit of the row number of the preceding switch, and repeating such acts with the just-identified switch as a preceding switch. Additional comparator circuitry, quantizers, and encoding circuitry can be part of the same integrated circuit as the array.