Air Radio Communication Systems

26-Channel (24 Proportional + 2 Toggle)/ 18-Channel (16 Proportional + 2 Toggle) System

FASSTest transmits 26 channels (or 18 channels) of data at high speed using an algorithm that efficiently handles more channel data.

Spread Spectrum Method

The Spectrum Spread Method is a method used in technologies like WiFi, and there are mainly two methods for spreading.

The first method is called Direct Sequence (DSSS), where the content to be communicated is broken down according to a certain code. On the receiving end, the data received in the broken-down state is restored using the code. By directly spreading, a strong communication link can be established against noise occurring in the same bandwidth. The strength of the code against noise increases with its length, but as the data volume increases, it affects the control response. Therefore, the length of the code is adjusted based on the balance with the amount of signal to be transmitted. This allows sending control commands for devices like radio-controlled models in the 2.4GHz band while minimizing the impact on other communications in the same frequency band.

The second method is called Frequency Hopping (FHSS), where the communication frequency rapidly switches in a predetermined pattern. Control data is grouped into chunks called packets, and these packets are sent out at predetermined intervals. Frequency hopping changes the frequency with each packet transmission. The receiver memorizes the pattern of frequency changes so that it can follow the transmitter’s frequency. This mechanism, combined with rapid frequency switching, minimizes the impact on other wireless communications in the 2.4GHz band, similar to Direct Sequence.
The Spectrum Spread Method is a method used in technologies like WiFi, and there are mainly two methods for spreading.

Furthermore, when the remote control is powered on, it searches the surrounding radio wave conditions and flexibly determines the pattern to transmit, enhancing safety even further.

FASSTest achieves higher communication reliability by using a combination of these two methods (Hybrid Method).

12-Channel Mode (10 proportional + 2 toggle)

While FASSTest can utilize various telemetry sensors in normal mode, the pilots who desire much faster response can use “12ch-mode” to enjoy extreme lower latency for more “locked-in feeling.”

In this mode, control data is updated with more than twice the speed of normal mode, boasting the fastest response class in the category.

In this mode, the telemetry function can only monitor the voltage of the receiver battery, and other sensors cannot be used.

Telemetry

The transmitter has a telemetry communication function that receives various information from the aircraft (such as battery voltage, motor RPM, temperature, etc.) to the transmitter.

Unique ID System

Each transmitter is assigned an individual ID code during the manufacturing stage, and the receiver memorizes the ID code of the transmitter through the “link” operation. As a result, the receiver only accepts signals from the linked transmitter, eliminating concerns about interference issues between RC models at the same flying field. (This system is equipped in all Futaba 2.4GHz transmitters.)

Additionally, FASSTest and T-FHSS feature the Model ID function. The Model ID function serves as a safety feature that prevents the receiver from responding if model data with settings that do not match the aircraft is mistakenly selected.

FASST is Futaba’s first 2.4GHz system specially engineered for RC system by utilizing the industrial class spread spectrum processing IC and established secure 2.4GHz link under crowded radio situation by employing Hybrid Spread Spectrum sytem unlike other competitors failure to keep a stable RF link.

Although it is a unidirectional communication system but some receiver are equipped with a “high-speed mode” that provides faster response with 7mS of refresh cycle and it dramatically changed the flight maneuver of helicopter’s demonstrations.

T-FHSS is next generation system of S-FHSS that employed the telemetry communication.

Practical performance such as effective radio range is comparable to FASSTest, and you can enjoy flights using telemetry sensors with peace of mind.

However, it does not have the 12-channel mode that FASSTest is equipped with, so it is a reasonably priced system for those who do not need that much functionality.

This is the previous generation of T-FHSS and is a monodirectional S-FHSS can control 8 channels maximum.