A method of synchronizing signals, comprising: using a clock tracking system to convert a future event target time specified in a time base of a master device into the local unsynchronized time bases of one or more slave devices; and generating, by the or each slave device, an event signal at the converted time, such that a coordinated delivery of synchronized signals is achieved; wherein the step of converting a future event target time is based on an estimation algorithm, the estimation algorithm providing a conversion which maps time values between the master device time base and a slave device time base, the method further comprising determining the conversion at the or each slave device from a plurality of clock calibration messages received at a respective slave device from the master device by a process including: receiving the plurality of clock calibration messages with respective transmission timestamps indicating transmission times of respective clock calibration message in the time base of the master device, determining respective reception timestamps for each clock calibration message in the slave device's time base indicating a time of reception of the calibration message, and providing the transmission and reception time stamps from the clock calibration messages as input to the estimation algorithm after modifying either the transmission timestamp(s) or the reception timestamp(s) based on a time-of-flight, TOF, value indicating a time for a clock calibration message to travel from the master device to the slave device; and wherein the step of converting the future event target time is performed using the state of the estimation algorithm as updated using the processed clock calibration messages. using a clock tracking system to convert a future event target time specified in a time base of a master device into the local unsynchronized time bases of one or more slave devices; and generating, by the or each slave device, an event signal at the converted time, such that a coordinated delivery of synchronized signals is achieved; wherein the step of converting a future event target time is based on an estimation algorithm, the estimation algorithm providing a conversion which maps time values between the master device time base and a slave device time base, the method further comprising determining the conversion at the or each slave device from a plurality of clock calibration messages received at a respective slave device from the master device by a process including: receiving the plurality of clock calibration messages with respective transmission timestamps indicating transmission times of respective clock calibration message in the time base of the master device, determining respective reception timestamps for each clock calibration message in the slave device's time base indicating a time of reception of the calibration message, and providing the transmission and reception time stamps from the clock calibration messages as input to the estimation algorithm after modifying either the transmission timestamp(s) or the reception timestamp(s) based on a time-of-flight, TOF, value indicating a time for a clock calibration message to travel from the master device to the slave device; receiving the plurality of clock calibration messages with respective transmission timestamps indicating transmission times of respective clock calibration message in the time base of the master device, determining respective reception timestamps for each clock calibration message in the slave device's time base indicating a time of reception of the calibration message, and providing the transmission and reception time stamps from the clock calibration messages as input to the estimation algorithm after modifying either the transmission timestamp(s) or the reception timestamp(s) based on a time-of-flight, TOF, value indicating a time for a clock calibration message to travel from the master device to the slave device;