Radio control cars terminology and grandiose system facts

When analyzing radio control cars system, the CRC (Cyclic Redundancy Code) is very important, because the security is the whole system, is the checksum obtained performs a mathematical operation with all the binary words sent to the receiver. In this case the receiver is not dumb, but it also has a microprocessor that receives the frame, it performs the same mathematical operation that compares the sender and the CRC checksum been obtained. If both agree that means that the received signal is valid in this case is used every word in the phrase to generate a digital pulse width variable that is sent to the corresponding servo.

If the checksum received does not match the received CRC that means the signal has been corrupted by the way because of interference in this case is still sent to the servos the last valid signal received. If the interference is short (which is usually did not call “glitch” nor will we realize that we had, because the next frame that arrives will be valid and sent to the servos. If the interference is permanent (i.e. because someone turned on a radio in our same frequency, or even because we have spent the battery of the transmitter) can program the receiver to continue sending the last valid signal, or we can choose to schedule a "fail safe".

This is meant to bring the radio control cars servo to a predetermined position, in the case of a car engine is cut, in the case of a plane is usually left the engine idling and take control surfaces to the point. It is a magnificent procedure. The advantages are obvious, but there are also disadvantages. The most important of this analysis is the delay. The frames that are much longer send the trains of pulses that are sent in the radio control cars PPM system, so the system is slower, and in some disciplines "adrenaline" is you may notice the delay between the command sent and the response of the model.

Each radio control cars manufacturer is looking for ways to minimize this problem, for example, there are codes in the PCM frame in an absolute position sent even channels and odd contrast, and the next frame to send different pairs and odd absolute position. In this way they get "scrape" milliseconds to make the system faster, although it is currently impossible to reach the speed of response of the PPM.