Radio gear

= Introduction =

RC "Radio Control" also known by the incorrect term remote control is the essential equipment used to keep your model under control while it is up in the sky while you are on the ground.

= Programming Tips =

What is Expo?
= Frequency =

AM
The information is the changing of the amplitude of the signal (amplitude modulation) (for loudness) and the rate of change of the amplitude for frequency of the "sound" as applied to broadcast signals on your "every-day" radio.

FM
Frequency modulation. This is the system used for VHF broadcast radios and can give stereo better quality than AM. As the frequency is modulated (changed) to transmit the information, it is used on higher frequencies and takes up more "space" i.e. a greater frequency range. It is the change in frequency that gives the information.

2.4Ghz
TERMS

DSM - Digital Spectrum Modulation

DSM2(TM) - Digital Spectrum Modulation V2

DSMX(TM) - an advanced DSM and said to be equal to in performance FHSS

DSSS - Direct Sequence Spread Spectrum

FAAST - Futabu's Frequency Hopping Spread Spectrum

FHDSS - Frequency Hopping Digital Spread Spectrum

The two main Spread Spectrum systems are FHSS or DSSS.

FHSS (Frequency Hopping Spread Spectrum)

What Happens

DSM

RC Heli Wiki DSM

DSM and DSM2 are the Spektrum 2.4GHz microwave radio protocols.

Both are Direct Sequence Spread Spectrum (DSSS) technologies. When the receiver is bound to the transmitter, it learns the transmitter's unique identification code. When the transmitter is first switched on, it scans for two free channels and then broadcasts on both simultaneously. The receiver searches the channels for the two containing its transmitters identification code, and then receives data from just those two channels. If one channel is interrupted by interference, then the receiver will notice that the packet is corrupt and can continue working on one channel.

In February of 2011, Spektrum launched a new technology called DSMX adding frequency shifting. DSMX combines the superior data capacity and interference resistance of a wideband signal (like that used in DSM2) with the agility of frequency shifts. DSMX Equipment is backwards compatible with DSM2, when operating in DSM2 mode. DX8 Transmitters can be upgraded by downloading Spektrum AirWare v2.0 and updating firmware using the SD card. All DSM2 transmitters, except the DX5e, are eligible for the add-on for $75 by sending them to the Horizon Hobby Service Center. DSM2 receivers and transmitter modules are not eligible for the DSMX add-on.

DSSS (Direct Sequence Spread Spectrum)

Is the better solution and is more reliable than FHSS type systems. DSSS systems operate on a very wide band. With DSSS there is significant increases in range capability.

FAAST

FAAST

FAAST Technology

FASST is Futaba's 2,4GHz protocol. FASST is a Frequency Hopping Spread Spectrum (FHSS) technology, where the transmitter broadcasts for a very short slice of time on one channel, before switching to another in an apparently random sequence. During the initial binding of the receiver to the transmitter, the receiver remembers the transmitter's unique identification code, and searches for a transmission containing this code when it is powered up. When it finds the code, it is able to predict when and where the transmitter will jump to next.

If the channel the transmitter jumps to is in use, the receiver will notice that the packet is corrupt and drop it. It still knows where the transmitter will broadcast in future so it is able to re-establish the link. 2.4GHz equipment is deliberately designed to be able to cope with such interruptions in the transmission.

Each FASST transmitter only works with a number of models of FASST receiver. Check the compatibility chart on Futabu's site before buying. FASST aeromodelling radios can work in one of two modes, for use with different receivers. The "7-channel mode" is used by receivers and transmitters up to 7 channels, whereas the "multi-channel mode" is used when a receiver with more channels is needed.

FHSS (Frequency Hopping Spread Spectrum)

This is where the controller transmits a narrow band signal and rapidly hops from one frequency to the next. The time that it takes to hop from one frequency to the next is only a couple of milliseconds. This FHSS system is was the first used and although helpful, it had several limitations that made it not as reliable as DSSS.

= Brands =

Futaba
Futabu uses FHSS (Frequency Hopping Spread Spectrum) with the 4YF and S-FHSS on the 6 Ch T6J and FAAST (Futabu Advanced Spread Spectrum) on the 7 Ch R617 and these are not compatible.

JR
JR Japan Remote Control

They developed DSM2 inconjunction with Spektrum. With the lapse of the alleged Spektrum agreement both firms set about releasing individual signal protocols. JR have the DMSS (Dual Modulation Spectrum System) - ref. RCM&E magazine Dec 2011.

According to JR, this gives the best features of Frequency Hopping Spread Spectrum (FHSS) and Direct Sequence Spread Spectrum (DSSS) protocols.

Spektrum
Spektrum are a good candidate for being the first major player on the market with the 2.4Ghz Spread Spectrum radios. While they have some car radios which I am not familiar with they have released 3 entry to mid level radio systems for flight use.

1. The DX6 can only control DSM receivers.

2. To control a DSM2 receiver you need a DX5e, DX6i, DX7, DX8 and the (as yet to be released) DX7s and DX10

3. The new DX6i will control the new DSMX receivers as well as DSM2 and DSM. This is so for the new (or updated to DSMX) DX6i regarding DSMX and DSM2 but not for DSM, but the Rx will only operate in DSM2 mode with older DSM2 (only) DX6i.

DX6 won't work with AR500

Turnigy 9x
Low cost but appears to be a serious contender. Has memory for 8 models.

FrSky
FrSky has a complete range of 2.4Ghz radio modules that will fit into most PPM compatible radios.

They are locally distributed and supported by Phlatkits

Resellers are being established at the moment to widen the local support network.

North Island
KiwiRC

South Island
Still looking for agents down that way.