of the dibit encoding is shown fig3 with a having a dibit of 1 and 1 and with b having a dibit of 1 and u2212 1 the complement can also be encoded namely d a dibit of u2212 1 and u2212 1 as the complement for a and c a dibit of u2212 1 1 as the complement for b in general as shown in fig3 this provides four possible coding states although the carrier frequency is not shown the carrier frequency can be the same for each device with the dibit adding to the number a surface acoustic wave devices that can be used in a wireless multi tag system as an example if each bit is implemented as a bragg reflector on an ofc device with a in channel 1 and b in channel 2 then the sum and differences and the on and off states can be used for device encoding further let 39 s assume in channel 2 which uses dibit b there is an external switch that can be used to engage on or disengage off channel 2 further the outputs after any switch are summed if channel 2 is off then the output will simply be a code 1 1 in the adjacent bits with a normalized amplitude of 1 and a length 2 u00b7 t bit when the switch is on the sum of the dibits will be a 1 0 in adjacent bits with a normalized amplitude of 2 and length t bit the energy in both of the received coded information will be the same the autocorrelation of.