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Your Reviewer

My Credentials
So who's doing this reviewing then?

Well I've been building and flying or driving radio controlled models for over 40 years and during that time I like to think I've built up a reasonable amount of knowledge.

I'm also a qualified electronics engineer who has worked in radio frequency, analog, digital systems and software for more than three decades. In fact I designed and built my first RC set back in 1969.

For the past nine years I've also been involved in the design and manufacture of some rather sophisticated engine technology and UAV flight control systems.

So, chances are I've been there, done that and have a huge pile of tee shirts to prove it.

Right now I'm heavily into 3D flying and enjoy all aspects of the RC hobby. I may be old but I don't feel it.

In the Pipeline

Here's just a little bit of what's to come on this site...

RC explained: Demystifying terms such as PCM, PPM dual conversion, single conversion, full-range etc., this feature will explain it all.

Cheap Chinese Engines: Just how good are those cheap Chinese glow and gas engines that sell for half the price of their "brand-name" equivalent? I put several to the test.

Build your own radio gear?: Back in the old days, building your own RC gear was not uncommon and now the arrival of 2.4GHz has made it practical again.

 

Assan V2 DSS Review (part 2): The Receiver

Assan has a wide range of receivers but I only had the small 4-channel unit to test and you can see it in the image above, compared to the Corona DSSS 4-channel unit.

One of the big plusses of the Assan system is that, when used with a transmitter capable of delivering 9 channels in FM/PPM mode, it will actually deliver all those 9-channels when the appropriate receiver is used. By comparison, most other Chinese module-based 2.4GHz systems are limited to 8-channels, even when used on a true 9-channel radio like the JR.

Unfortunately (as mentioned earlier) I was not at liberty to rip the heatshrink off the small Assan receiver to inspect the build-quality but it certainly appears to be well made (from the outside).

Assan uses the concept of a bind-plug rather than a bind-switch on the receiver itself. This is probably a better setup than Corona's bind switch because it means there's no chance of the receiver accidentally entering bind-mode, even if it shifts around in flight.

The receiver has two LEDs, a red one (which flashes until a link is established) and a green one that is illuminated once the link is achieved. Unfortunately, in the small 4-channel unit, it's almost impossible to see the green LED through the white plastic heatshrink and in fact I didn't even notice it until I was doing some tests in the late afternoon and the sun's light was fading.

The tests: How does it stack up?

The first thing I noticed was that Assan have done an excellent job of producing a very *smooth* system in terms of servo movement.

There was no sign of jitter or hesitation from the servos when the transmitter sticks were moved. This made the whole system feel very solid -- engendering a strange feeling of confidence.

The only other system tested so far that provides the same measure of smoothness is the FlySky (iMax/Turnigy) 9X when using the FlySky 2.4GHz modules and receivers. Although the Corona DSSS system is better than their FHSS system, the Assan takes things to another level.

While the receiver was on the bench I wound down the operating voltage until the very hard to see green LED (which signals that a link is established) went out. Like most of the other Chinese-made receivers tested to date, the Assan kept on working right down to a very respectably low voltage -- 2.29 volts to be exact. When the voltage was restored to just over 2.5V it bounced back immediately and began working again with no perceptable delay. That's good, very good.

The next check was to see how the system makes use of the 2.4GHz band so I fired up the spectrum analyzer.

Unfortunately, it appears that the sample tested, despite bearing the "V2" labels, had an old version of the firmware installed so performed rather poorly here, using only a single DSSS channel with no redundancy or agility.

Herein is a problem for prospective Assan purchasers -- there is no way to deterimine whether the Assan system you're thinking of buying or have just bought is the newer version (that uses two segments of the band) or an older one that uses just one.

This is very unfortunate and a bad move on the part of Assan.

While, under ideal conditions, virtually all of the 2.4GHz systems tested so far work just fine, the need for some kind of frequency agility (in the form of hopping) or redundancy (in the form of using multiple parts of the band) becomes a major factor in determining the reliability and resilience of the system.

Just like the single-frequency FlySky system, the Assan system I reviewed may work just fine for 99.9% of all users but if it does encounter strong interference on the part of the band it's using -- there's no backup plan, nowhere for it to go, and a crashed model may result.

At the very least, Assan should have made it easy to tell if you have the old or the new firmware installed - that they haven't is not so good.

The upcoming module shoot-out will reveal just how resilient the Assan is to the type of interference you may encounter in the real world. The fact that this is a single-frequency system may well count against it but, until Assan mark these modules so you can tell, there's no way to guarantee that you'll not be getting an old-stock version so there's not too much point in me purchasing a system for those tests until I can be sure I'm getting a later version.

One aspect that I'd hoped would put Assan at the top of the list of Chinese-made 2.4GHz module/receiver combos is failsafe.

My big gripe with all the other Chinese-made systems so far is that none of them have offered a useful failsafe capability.

Well it's true that the Assan does offer a failsafe but it's far from what I'd call "good".

Each time you power up the receiver, the initial stick positions on your transmitter are registered as the failsafe settings for that flight. Since many people flying fast/large models in areas where it's dangerous to have a model fly very far in an uncontrolled condition prefer to set their failsafes to produce a snap-roll (eg: full up, full right rudder and full left aileron or whatever), having to hold both sticks in these positions while operating the receiver switch is ridiculously awkward.

Other module-based systems such as XPS and WFly have perfectly practical ways of setting their failsafe settings without the need for an excellent memory and physical gymnastics -- so I consider Assan's solution to be better than nothing but marginal at best. What a shame.

Initial ground-range tests seem excellent but a full range comparison between the Assan and oher module-based systems will feature in the upcoming shootout article.

Summary

In terms of its basic functionality it's hard to fault the Assan. It works as advertised, is very smooth, easy to bind and is resilient to brownouts and reboots.

In a few areas it's better than Corona but it falls frustratingly short of the "perfect" score I was expecting to end up awarding it.

I'd really like to use one of the dual-channel Assan systems for the interference tests coming up here at RCModelReviews but I'm not about to lay out money for a system until I can be sure it too doesn't come with outdated firmware (and remember, there's no way to tell until you test it).

Pro's:

  • It works and there are very few reported issues in the field
  • Very smooth, better than Corona, FlyDream and others
  • A good range of receivers
  • Excellent resilience to brownouts/reboots
  • Futaba module works equally well in Hitec radios
  • A true 9-channel system when used with JR9X/9303 radios

Con's:

  • Poor physical design of the transmitter module antenna attachment
  • Failsafe is pretty poor (marginally better than nothing)
  • No way to tell if you have the original 1-frequency or more recent 2-frequency version
  • The version I tested was non-agile and offered no frequency redundancy

  • Product: Assan V2 DSSS 2.4GHz module/receivers
  • Supplied by: an RCModelReviews reader (on loan)
  • Price: around US$90 for the combo of 1 module + 2 receivers
  • Overall raiting: 4.55 out of 5

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The Blog

Updated: 20 Sep 2012
Here's a blog that will keep you informed just what's going on behind the scenes at RC Model Reviews and also tells you a little more about myself.

How compatible are 2.4GHz RC systems?

23 Mar 2010
How come there's no compatibility between different brands of transmitters and receivers? Why can't you use a cheap Chinese receiver with your Futaba FASST radio?

How to get a product reviewed here

4 Mar 2010
Since this has become a very frequently asked question, I've posted this simple guide to getting your product, or a product you're thinking of buying reviewed here at RCModelReviews

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