A pulse transponder countermeasure device, comprising: a central processing unit (CPU); an optical receiver adapted to receive detection signals from a speed measuring device; at least one optical transmitter adapted to transmit jamming signals to the speed measuring device; at least one software controlled driver configured to drive the optical transmitter and memory storing a database of measuring devices signature signals and reflective signals, the CPU configured to identify the speed measuring device in its database according to the received detection signal's signature and calculate a response time for sending a jamming signal to the speed measuring device so as to change the speed perceived by the speed measurement device.