A method of receiving data from a telemetry module, the data being modulated according to a quadrature amplitude modulation encoding scheme, in which a receiver has a carrier recovery circuit comprising a phase detector, a loop filter and a signal synthesiser generating an inphase and a quadrature demodulation signal, the method comprising the steps of: a) receiving a preamble sinusoidal signal representing a symbol; b) matching the phase of the inphase signal generated by the signal synthesiser to the phase of the received preamble signal; c) matching the phase of the quadrature signal generated by the signal synthesiser to be ninety degrees out of phase with the phase of the received preamble signal; d) determining whether the received preamble signal represents a symbol having positive inphase and quadrature components; and in the event the components are not both positive, adjusting the phase of the inphase and quadrature components by a fixed phase shift and repeating the step of determining whether the received preamble signal represents a symbol having positive inphase and quadrature components until the received preamble signal represents a symbol having positive inphase and quadrature components; e) determining the cross product of the received inphase and quadrature components and ideal inphase and quadrature components; f) indexing a look up table with said cross product to determine a phase adjustment; and g) adjusting the phase of the demodulation signals in accordance with said determined phase adjustment; the method further comprising receiving a data signal from the telemetry module, and adjusting for small phase rotations due to frequency fluctuations by: h) determining whether the received data signal represents a symbol having equal inphase and quadrature components; i) in the event the received data signal represents a symbol having equal inphase and quadrature components, updating a phase difference measure in dependence upon the difference between the magnitude of the inphase and quadrature components of the received data signal; and j) adjusting the phase of the signals generated by the signal synthesiser when said phase difference measure exceeds a predetermined threshold. a) receiving a preamble sinusoidal signal representing a symbol; b) matching the phase of the inphase signal generated by the signal synthesiser to the phase of the received preamble signal; c) matching the phase of the quadrature signal generated by the signal synthesiser to be ninety degrees out of phase with the phase of the received preamble signal; d) determining whether the received preamble signal represents a symbol having positive inphase and quadrature components; and in the event the components are not both positive, adjusting the phase of the inphase and quadrature components by a fixed phase shift and repeating the step of determining whether the received preamble signal represents a symbol having positive inphase and quadrature components until the received preamble signal represents a symbol having positive inphase and quadrature components; e) determining the cross product of the received inphase and quadrature components and ideal inphase and quadrature components; f) indexing a look up table with said cross product to determine a phase adjustment; and g) adjusting the phase of the demodulation signals in accordance with said determined phase adjustment; h) determining whether the received data signal represents a symbol having equal inphase and quadrature components; i) in the event the received data signal represents a symbol having equal inphase and quadrature components, updating a phase difference measure in dependence upon the difference between the magnitude of the inphase and quadrature components of the received data signal; and j) adjusting the phase of the signals generated by the signal synthesiser when said phase difference measure exceeds a predetermined threshold.