Figure 1: Effect of Improved Response

 F-4G is the mode that boasts the fastest response in the Futaba car system.

 The key point in speeding up the response is how to speed up the cycle of transmitting information about steering, throttle, and other radio control operations to the receiver.
 In response to this theme, Futaba’s car 2.4GHz system has evolved from the FASST series C1 and C2 * to variations of the FHSS series, and the completed product is the car system T-FHSS SR mode. . However, Futaba was not satisfied with this, and in order to further speed up the response, they reviewed the signal processing method from scratch and succeeded in developing a new system called “F-4G”.

 F-4G achieves approximately twice the response of T-FHSS SR mode. This further refines the sense of “on the rail” driving, and in extreme races, the distance traveled while driving is half that of the previous system, increasing the accuracy of tracing the desired line. This has been dramatically improved and will become a major point that will set you apart from your competitors.

 In addition, the F-4G compatible receiver uses a diversity system equipped with two antenna systems to minimize the possibility of reception interference. The selection algorithm for the two antenna systems has also been carefully tuned to suit the environment in which it will be used in a car, ensuring that the transmitted signal is captured in the best possible condition even in constantly changing reception conditions while driving. , effectively brings out the performance of the F-4G. In addition, the F-4G’s true value is demonstrated by using a servo compatible with “UR (Ultra Response) mode”.

We succeeded in shortening the time to half of the previous one, further refining the sense of “on the rail” operation.

Figure 2: Receiver Side Diversity Antenna

By shortening the transmission cycle and using the diversity system, a faster and more stable response is ensured. In addition, the telemetry function could not be available in the previous fastest mode, T‑FHSS SR mode, but the F-4G can use it.

The receiver’s 1‑4 channel ports can be individually configured for analog/digital/SR mode/UR mode. In addition, it is possible to control up to 10 channels, which is the maximum for a car controller.

Figure 3: F-4G can more accurately transmit operational status to receiver.

Spread Spectrum System

Within the 2.4GHz band, signals of digitally modulated are communicated while switching frequencies at high speed of milliseconds order. This allows transmitter control commands to be sent to the receiver while minimizing interference with other communications, including those for RC, that exist in the 2.4GHz band.

Figure 4: Image of Frequency Hopping

Diversity Antenna (Receiver Side)

Equipped with dual receiving antennas, it contributes to keeping the best-receiving capability under various situations like wiring shading, the reflection of radio waves, etc.

Unique ID System

Each radio is given a unique ID code at the manufacturing stage, and the receiver can memorize the ID code of the controller to be linked by “link operation”. This will allow the receiver to accept the signal from the linked controller. Therefore, there is no need to worry about any glitch between RC at the same field and no “frequency pin” are necessary.


This mode is a car system with faster response than normal (T-FHSS)mode and controls of up to 4 channels. As this mode, to minimize the latency, the telemetry function is not available. You can select ON/OFF of SR mode for each CH port of the receiver. Also, when SR mode is ON, please use a servo that supports SR mode. When SR mode is OFF, it is digital servo-only mode.


The telemetry function is available at this mode and can control up to 4 channels. “High speed mode” using digital servo and “normal mode” using analog servo can be selected.


This mode is monodirectional communication system and can control up to 8 channels. “High speed mode” using digital servo and “normal mode” using analog servo can be selected.(*)

(*)Some model can not switch the mode.


This is first generation of FHSS system and employs unidirectional communication. Up to 4 channels can be controlled for analog/digital servos.