  Specific low-bitrate coding strategies are examined through their effect on
LQ control performance. By limiting the subject to these methods, we are able
to identify principles underlying coding for control; a subject of significant
recent interest but few tangible results. In particular, we consider coding the
quantized output signal deploying period-two codes of differing
delay-versus-accuracy tradeoff. The quantification of coding performance is via
the LQ control cost. The feedback control system comprises the coder-decoder in
the path between the output and the state estimator, which is followed by
linear state-variable feedback, as is optimal in the memoryless case. The
quantizer is treated as the functional composition of an infinitely-long linear
staircase function and a saturation. This permits the analysis to subdivide
into estimator computations, seemingly independent of the control performance
criterion, and an escape time evaluation, which ties the control back into the
choice of quantizer saturation bound. An example is studied which illustrates
the role of the control objective in determining the efficacy of coding using
these schemes. The results mesh well with those observed in signal coding.
However, the introduction of a realization-based escape time is a novelty
departing significantly from mean square computations.
