A sports timer system for equestrian sports, the sports timer system comprising a main timing unit configured to calculate a time interval; a display device configured to display information; characterized by : a first pair of circular optical transceiver configured to generate a first signal based on an equestrian competitor crossing a start line; a second pair of circular optical transceiver configured to generate a second signal based on an equestrian competitor crossing a finish line, wherein the first pair of circular optical transceiver and second pair of circular optical transceiver transmit and receive light in a time division multiplexed mode in accordance to a time shot schedule, enabling multiple optical transceivers to be synchronized without cross interference between the transceivers; wherein the main timing unit is configured to: receive the first signal and the second signal, and calculate a time interval between the reception of the first signal and the second signal; and wherein the display device is configured to display information regarding the time interval. a main timing unit configured to calculate a time interval; a display device configured to display information; characterized by : a first pair of circular optical transceiver configured to generate a first signal based on an equestrian competitor crossing a start line; a second pair of circular optical transceiver configured to generate a second signal based on an equestrian competitor crossing a finish line, wherein the first pair of circular optical transceiver and second pair of circular optical transceiver transmit and receive light in a time division multiplexed mode in accordance to a time shot schedule, enabling multiple optical transceivers to be synchronized without cross interference between the transceivers; wherein the main timing unit is configured to: receive the first signal and the second signal, and calculate a time interval between the reception of the first signal and the second signal; and wherein the display device is configured to display information regarding the time interval. a first pair of circular optical transceiver configured to generate a first signal based on an equestrian competitor crossing a start line; a second pair of circular optical transceiver configured to generate a second signal based on an equestrian competitor crossing a finish line, wherein the first pair of circular optical transceiver and second pair of circular optical transceiver transmit and receive light in a time division multiplexed mode in accordance to a time shot schedule, enabling multiple optical transceivers to be synchronized without cross interference between the transceivers; wherein the main timing unit is configured to: receive the first signal and the second signal, and calculate a time interval between the reception of the first signal and the second signal; and wherein the display device is configured to display information regarding the time interval. wherein the main timing unit is configured to: receive the first signal and the second signal, and calculate a time interval between the reception of the first signal and the second signal; and receive the first signal and the second signal, and calculate a time interval between the reception of the first signal and the second signal; and wherein the display device is configured to display information regarding the time interval. <EOS>