Let’s look more closely the RC truck we saw on the last page. Let’s assume that the exact frequency used is 27.9 MHz. Here is the sequence of events that occur when you use the RC transmitter :
- A trigger is pressed so that the truck to follow later.
- The trigger causes a pair of electrical contacts to the touch, completing a circuit connected to a specific pin of an integrated circuit (IC).
- The full circuit makes the transmitter to transmit a sequence of electrical impulses set (see how the radio for more details). Each script contains a short sync pulse group, followed by the sequence of pulses. For our truck, the segment of synchronization – which alerts the receiver to incoming information – is four pulses that are 2.1 milliseconds (thousandths of a second) in length, with 700 microseconds (millionths of a second) intervals. The segment of pulse, which narrates the antenna so that the new information is, uses pulses of 700 microseconds with 700 microsecond intervals.
Sequences of pulses
- Front: 16 pulses
- Reverse: 40 pulses
- Front / left: 28 pulses
- Front / right: 34 pulses
- Reverse / left: 52 pulses
- Back / right: 46 pulses
- The transmitter sends bursts of radio waves that oscillate with a frequency of 27.9 million cycles per second (27.9 MHz). If you have read how Radio Works, you will recognize this as pulse modulation.
- The truck is constantly monitoring the assigned frequency (27.9 MHz) for a signal. When the receiver receives radio bursts from the transmitter, it sends a signal to a filter that blocks any signals collected by the different 27.9 MHz antenna. The remaining signal again becomes a sequence of electrical pulse.
- The pulse sequence is sent to the IC on the truck, that decodes the sequence and starts the motor. For our example, the sequence of impulses is 16 pulse (forward), which means that the IC sends current positive motor running wheels. If the following sequence of pulses were 40 pulses (reverse), CI would be to invest today for the same motor to spin in the opposite direction.
- The motor shaft actually has a gear on the end of it, instead of connecting directly to the shaft. This slows down the speed of the motor, but increases the torque, giving the truck power right through the use of a small electric motor!
- The truck moves forward.
If you look at the inside of the truck RC, you will see that it is very simple. Now let’s take one look more closely at each of the main components in how Radio controlled toys work, part III – on the inside of a truck RC.