2.4 gigahertz Spread Spectrum technology has been slowly revolutionizing the R/C community over the past few years. The technology, called DSSS - Direct Sequence Spread Spectrum, puts the control of the model out of the range of 'traditional' sources of interference from electrical noise and mechanical vibrations.

Sanwa (Airtronics in the USA) were slow to release their own system and competitors like 'Spektrum' have been enjoying a near-monopoly on 2.4ghz R/C.

Sanwa's system is rather unimaginatively called DSSS - that's it. A bit like calling their next transmitter - 'Transmitter'. The name aside, its about time that Sanwa provided their own 2.4 ghz system, so let's take a closer look.

The Sanwa DSSS system comes as a set, with transmitter module and receiver neatly packaged in a foam-lined box.

Before even opening the box, it's notable just how light the components are - the module itself feeling almost worryingly light. I did take it apart just to make sure :)

The first thing to strike me having not really seen this system before is the mock-crystals. These are actually backlit buttons which are used to setup the system when installed.  The receiver looks to use the case from one of their existing ‘traditional’ micro receivers – hence using the crystal socket for the button.

Whilst the receiver is indeed very small, it’s still a way off the über-tiny Spektrum pro offerings. 

The transmitter module and receiver are accompanied by a single page instruction sheet and some rubber plugs for the receiver (to keep the dust out).  I searched high and low and was disappointed to find there was no transmitter antenna plug to blank off the hole if you decide to remove the antenna.

The module is a straight swap out for the existing module on your Sanwa / Airtronics transmitter.  I was converting the M11 steer wheel transmitter but the system is compatible with the older M8 as well as the Super EXZES and Super EXZES Plus stick transmitters.

A quick push home is all that’s required to install the module, and this could become a pretty frequent act, since the small antenna on the module isn’t removable, making it incompatible with most transmitter cases.

The antenna (right) isn't exactly 'cheap and flimsy' but its position is likely to receive some knocks and bumps at race meetings - especially in the transmitter compound.
It's a shame that Sanwa couldn't have come up with a simple screw-in mount for the antenna. My cheap Wifi adaptor has one so why not!

With the transmitter ready I set about installing the receiver in my Tamiya 501X.  The aerial length on these 2.4ghz systems, if you didn’t already know, is tiny in comparison to traditional gear.  It still needs mounting vertically though to get the best reception.  The Tamiya 501X isn’t the easiest car to install a receiver in, in fact it’s a nightmare trying to thread the aerial wire through the aerial mount, and taking half the car apart seems necessary.  The small size of the Sanwa receiver was welcome – but I was still mourning the memory of those tiny Spektrum receivers I’d seen.

Sanwa's receiver has 4 channels and thus plenty of sockets (5 in total), so adding an ESC fan or Personal Transponder, or even a receiver pack, should be no problem at all. Any unused sockets can be blanked off with the supplied rubber covers.

With the receiver safely installed it’s time to ‘bind’ these babies together.  The way DSSS works is by the transmitter and receiver being paired together -  this gives the two an unbreakable bond when in use, so even with others using the same frequency there would be no problem with interference.  The module and receiver both have unique codes and it’s these that they look for when communicating with each other.  The binding process stores the unique ID of the transmitter module in the receiver – so it knows to only respond to that transmitter in future (unless re-bound to another of course).  So if you have 2 or more cars all with Sanwa DSSS receivers, then once they are 'bound' swapping between the vehicles is a breeze – just turn on and go, with no setup or crystal changes to worry about.

Transmitter on!	Hold the button whilst turning the car on - hold for two seconds and let go. Hold the transmitter module button until the receiver light flashes quickly.	Both transmitter module and receiver lights should then light up bright and steady! Binding complete! Simple.

Binding the two took a couple of tries (I was tired, ok!), but once you get the hang of it, it’s pretty easy.  With the transmitter switched on, you hold the receiver button and turn the car on.  The ‘faux crystal’ on the receiver begins to flash slowly and after 2 seconds  you let go.   The next step is to press and hold the button on the transmitter module until the receiver begins to flash quickly – then the job is complete!
After a few seconds the lights on both transmitter module and receiver will stay lit and the vehicle is ready to go.  Thankfully, once this is ‘binding’ is done, it doesn’t need to be done again unless you change either the receiver or module.

Conclusion:
Sanwa have done a great job to finally get their own 2.4ghz DSSS system on the market and it’s a great addition to any compatible transmitter - but it's not clear exactly what it offers over and above the established competitors to distinguish itself. Of course it keeps the 'Sanwa' theme running through your equipment, if you are worried about things like that – indeed, if you are reading this far you’re probably already interested, which is why I bought the system over the pre-existing options.  Whilst there are no other ‘goodies’ available currently like those that Spektrum offer (telemetry, lap timing etc) the Sanwa system is slightly cheaper for what appears to be a very similar core product.  If it were more expensive than the competition it would make less sense.

Sanwa don't supply a plug so if you want to remove the original antenna from your transmitter (why not) you'll be left with a gaping hole, which can't be good. You can accept such an oversight from a third party manufacturer but since this is Sanwa's own system it seems a bit odd. I know it's a small point but then again, maybe Sanwa wanted to provide a handy pencil holder? (right)

The antenna on the module is in a precarious position and it's easy to imagine the sort of bashing and scraping this will get over the course of a season. It won't fit in my transmitter bag without some modification, and even then I'd probably not like to take the risk of the unit taking a knock with the thin padding of my bag the only protection. A simple screw-in mount for the antenna would have been a really nice feature here.  It is a shame that a more integrated system couldn’t have been devised, but perhaps it’s not technically possible – it IS possible to modify things to place the DSSS antenna in the original transmitter antenna position and Xtreme RC magazine have a handy tutorial on their site for the similar Spektrum system in an older M8 transmitter.

Overall, with the simple installation and setup - combined with the great performance and even greater practicality / ease of use of this system, it's hard to say anything really negative - hence the small points above. I'll be first on the list for a 'proper' dedicated 2.4GHZ M11 if they ever release one - but for now, the DSSS module is a great upgrade that's going to make things a whole lot easier.