Frequency conversion in a touch sensor

A touch sensitive device comprising:

• touch interface comprising rows and columns;
• signal generator for generating a plurality of unique orthogonal signals on at least a plurality of the rows, respectively, the plurality of unique orthogonal signals being in a first range of frequencies and having a first frequency spacing;
• heterodyning frequency mixer configured:
• to receive
• a column signal present on each of the columns, the column signals comprising signals within the first range of frequencies and having the first frequency spacing, and
• an oscillating signal, and
• to output
• a heterodyned signal for each column, each heterodyned signal based upon one of the column signals and the oscillating signal, the heterodyned signals each comprising signals within a second range of frequencies at the first frequency spacing;
• touch processor configured to identify touch on the touch interface based at least in part on the heterodyned signals.