The driver of any motor vehicle which has been checked by radar or by an electrical or mechanical timing device to determine the speed of the motor vehicle over a measured distance of the highway and found to be in violation of any of the provisions of this Traffic Code may be arrested until a warrant can be obtained, provided such officer has observed the recording of the speed of such motor vehicle by the radio microwaves, electrical or mechanical timing device, or has received a radio message from the officer who observed the speed of the motor vehicle recorded by the radio microwaves, electrical or mechanical timing device. However, in case of an arrest based on such a message, the radio message must have been dispatched immediately after the speed of the motor vehicle was recorded and the arresting officer furnished a description of the motor vehicle for proper identification and the recorded speed.