A tip clearance measurement system (TCMS) comprising: a probe that both directs signals toward a turbine blade and receives signals reflected by the turbine blade ; circuitry comprising: a switch having a first state in which a main frequency signal having a main frequency is provided at an output of the switch , the main frequency selected so that the main frequency signal is not substantially reflected at an end surface of the probe , and a second state in which a reference frequency signal having a reference frequency is provided at an output of the switch , the reference frequency selected so that the reference frequency signal is substantially reflected at the end surface of the probe ; a first conditioning circuit that receives a frequency provided at the output of the switch and provides a conditioned frequency to the probe ; a second conditioning circuit that receives both the conditioned frequency provided by the first conditioning circuit and a reflected frequency received by the probe , and provides a conditioned output based on the conditioned frequency and reflected frequency; and a controller that selectively controls the state of the switch to apply either the main frequency or the reference frequency to the output of the switch , wherein the controller applies the main frequency to the output of the switch , and then subsequently applies the reference frequency to the output of the switch , stores the conditioned output provided by the second conditioning circuit for both the main and reference frequency reflections; and determines tip clearance (d) based on the stored conditioned outputs provided by the second conditioning circuit . a probe that both directs signals toward a turbine blade and receives signals reflected by the turbine blade ; circuitry comprising: a switch having a first state in which a main frequency signal having a main frequency is provided at an output of the switch , the main frequency selected so that the main frequency signal is not substantially reflected at an end surface of the probe , and a second state in which a reference frequency signal having a reference frequency is provided at an output of the switch , the reference frequency selected so that the reference frequency signal is substantially reflected at the end surface of the probe ; a first conditioning circuit that receives a frequency provided at the output of the switch and provides a conditioned frequency to the probe ; a second conditioning circuit that receives both the conditioned frequency provided by the first conditioning circuit and a reflected frequency received by the probe , and provides a conditioned output based on the conditioned frequency and reflected frequency; and a controller that selectively controls the state of the switch to apply either the main frequency or the reference frequency to the output of the switch , wherein the controller applies the main frequency to the output of the switch , and then subsequently applies the reference frequency to the output of the switch , stores the conditioned output provided by the second conditioning circuit for both the main and reference frequency reflections; and determines tip clearance (d) based on the stored conditioned outputs provided by the second conditioning circuit . <EOS>