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Jul 19, 2007, 01:07 PM
Proud member of LISF and ESL
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2.4 GHz - A Broad Market Review


2.4 GHz AIRCRAFT SYSTEMS
A BROAD MARKET REVIEW
by Ed Anderson
aeajr on the forums

This broad market review is provided to help prospective 2.4 GHz users
understand what is going on in the market. As each of the 2.4 GHz brands uses a
different communication standard, they are not compatible with each other. This
means that a decision to move into the 2.4 GHz is also a decision to use oneof
these 2.4 GHz implementations. I am going to examine what factors might
influence one's decision to go with one or the other.

It seems the 2.4 GHz airplane radio system market is growing fast. New flyers
are adopting it quickly and existing pilots seem to be very interested in moving
to this new environment for its promised safety and perhaps its faster response.
Manufacturers are now incorporating 2.4 GHz into RTF models. In my opinion, 2.4
GHz is not the wave of the future, it is the wave of today.

If we look at the currently available players we see Futaba, Extreme Power
Systems and Spektrum. JR is shipping 2.4 GHz systems based on the Spektrum
standard, so I will group them with Spektrum.

If we look at forum buzz as a market indicator Spektrum/JR appears to be the
dominant player with complete radio systems, announced transmitter modules for
JR and Futaba and a wide selection of receivers. Spektrum has been shipping 2.4
GHz radio control systems for several years and has a large user base in
airplane and RC cars and boats. Spektrum products are available from a variety
of hobby stores and internet sites.

XPS started shipping in April 2007. They would seem to be second with
a broad selection of transmitter modules and a couple of receivers. They are
sold from the XPS web site only as far as I can determine.

Futaba started shipping an entry level 6 channel transmitter/receiver combo
around April as well. They have announced upgrade modules for Futaba module
based transmitters but they have not started shipping as of this writing.

I am not going to focus on the specifics of their respective technologies except
as to how it would impact a user. They all seem to be getting good reports so
it appears they all work. While there are more problem reports on Spektrum,
their installed base is huge compared to XPS or Futaba so you would expect to
see more problem reports. I don't see this as a negative indicator and reports
are that Spektrum is doing a good job with customer service.

Note that high carbon content fuselages and some metallic coverings have always
been a problem as these can block radio signals. For 72 MHz, where the receiver
antenna is around 40 inches, this has been something that can be managed as the
antenna can easily be routed outside the plane. On 2.4 GHz systems the antennas
are tiny. Users are trying a variety of methods to get around the carbon
fuselage issue. If your planes don't have carbon or metal fuselages, this is
not an issue, but if they do, be aware that it could interfere with the 2.4 GHz
signal. Do some reading to see what is working and what is not. Make sure you
do careful range checks before you fly to insure you have good signal and no
dead zones where the signal is blocked.


XPS - Extreme Power Systems
www.extremepowersystems.net

XPS chose to go after the larger plane and experienced flyer market first. They
are only selling after market transmitter modules. They are not offering an XPS
transmitter. So, their target market is upgrade modules for existing owners
who have module based systems. This addresses the mid market to high end users
and really does not address the entry level market at all.

XPS initial offering is based on 8-10 channel receivers and a receiver design
that calls for a little more room in the plane than the other brands. If you
are flying glow, gas, medium to larger electrics and gliders with large spaces
in the fuselage, it seems that XPS has options for you. However if your
transmitter is not module based, or if you are buying your first radio, you
can't choose XPS. While XPS modules have more brand transmitter coverage than
Spektrum, you have to buy someone else's midrange to high end transmitter first
in order to adopt the XPS standard.

XPS has been more willing to share range specs than the others. They have a
small 6 channel receiver coming that looks good, from a specs and a price point
of view. The published specs say 1500 foot rated air range. That would be
great for most planes under 60 inch wing spans which is a huge part of the
market, especially the electric market. For planes larger than that, their
larger receivers will probably fit and do a good job.

For most slope gliders under 2M, the bulk of the slope market, the 6 channel
will probably be fine. For other gliders the XPS receivers could be a problem
either for size or range. For hand launched gliders their new 6 channel may or
may not fit and have enough range. For thermal duration gliders that are 1.7 M
or larger the 6 channel probably does not have enough range. For these larger
gliders, it remains to be seen if the 8 and 10 channel XPS receivers will fit in
many of the narrow fuselages, but range does not appear to be an issue.

XPS seems to handle low voltage receiver pack or BEC issues better than
Spektrum. Specs suggest that the XPS systems are faster to reboot if the pack
has a momentary drop below a critical voltage level. This can occur if servos
demand a lot of amperage causing a sag in the receiver pack or BEC voltage. I
don't know how Futaba handles this.

XPS also promises 2 way telemetry in the future. That could be a nice plus for
XPS users.

XPS uses a channel hopping approach to frequency management. They say that they
can have over 100 simultaneous users. With XPS you are highly unlikely to get
locked out due to the radio slots being all used up by XPS system users. Even
at large events with a hundred or more pilots, some will be on XPS, some on
other 2.4 GHz standards and some on 72 Mhz. Available channel space for XPS
users should not be a problem.

If another major radio provider, like Hitec or Airtronics were to announce
alignment with XPS that could be a big boost for XPS market share and acceptance
across a broader range of users. You could then buy a transmitter that is XPS
based. Or, if retailers were to sell new transmitters with XPS modules then you
could buy a Hitec Optic 6 or a Futaba 9C, for example, with an XPS module rather
than a 72 MHz channel module. It will be interesting to see what develops in
the market.


SPEKTRUM
www.spektrumrc.com

Spektrum targeted the parkflyer and micro heli market first when they released
their DX6. New RC pilots could buy a cost effective 6 channel computer radio
with a good range of features as their first transmitters and have no frequency
control issues to worry about. Reports suggest that this is the fastest growing
part of the market and one that will readily adopt a new standard so this was a
good starting point for building a new installed base. Once satisfied with the
Spektrum system these new flyers would likely stay with the Spektrum standard.
Based on forum buzz, the DX6 is still selling well as the price is holding up
with little discounting being seen.

The follow on DX7 works with the 6 channel DX6 receiver so there is an upgrade
path within the Spektrum label for those who want more channels and more
features. Now that JR has adopted the Spektrum standard, you can buy a full
range of transmitters that will work with Spektrum receivers.

If you are a new flyer, or if you are flying small planes or tight fuselages,
Spektrum has a wide selection of receivers going from micro receivers to 9
channel multi-receiver offerings. With JR adopting the Spektrum standard and
modules for Futaba coming out, Spektrum's base can expand even further.
Spektrum has established itself as THE dominant standard in the 2.4 GHz
airplane/heli market. They also have a major position in the RC car market. It
is unlikely that Spektrum will be the only major standard, but it will certainly
be one of the main standards.

Reports suggest that Spektrum's receivers are more vulnerable to low voltage
pack problems as their receivers are comparatively slow to reboot and reacquire
the transmitter signal. However, now that this is known, with proper planning
this should not be a major issue as you should take it into account in your
installation. While they have been resistant to releasing any numbers on
receiver ranges, the user community has been active in establishing some
acceptable ranges for their receivers. Seems Spektrum has been conservative in
their marketing information and their receivers can be pushed out further than
would have been initially suggested.

Spektrum's channel management approach limits their system to 40 simultaneous
users. While this number seems large compared to typical pilot population at
the field, as 2.4 GHz becomes the standard and frequency control starts to go
away, will Spektrum users be locked out at large events? While you might only
have 5 Spektrum pilots in the air at one time, you could easily have more than
40 Spektrum users at an event. If you have 40 Spektrum based transmitters
turned on in the pits, will you be locked out from flying even as you approach
the line? Again, we can expect that many pilots will be on other standards, but
will this become an issue in the future? It is something to consider if you
frequent large events.

FUTABA
www.futaba.com


What of Futaba? It is too soon to tell. There don't seem to be that many 6EX
2.4 GHz systems out there yet. Those who have them seem to report that they
work well but many are dissatisfied with the features of the transmitter and the
price for the features provided. However this does give Futaba an entry level
system for new buyers, though more expensive than the Spektrum DX6. If you take
the price of servos into account, it is about the price of the DX7 but with a
vastly more limited feature set than the DX7.

We really can't rule Futaba out as they are a major force in the market. They
are just a bit late and slow to get up to speed and their prices are higher than
Spektrum or XPS for the features delivered. Futaba seems to be focused on
Futaba customers at this time as they have made no announcements of modules for
other brands. Once they get rolling, they may become a major player in this 2.4
GHz market. I am sure their technology is good, but will it be niche, like PCM,
or will it become a market standard. Only time will tell. If Hitec, or
someone, else were to adopt the Futaba standard that would be a huge boost for
their market position. This is the dark horse player at this time.


A Personal Prospective

As an experienced flyer who already owns two module based transmitters, I like
that XPS is available for just about anything including my Futaba 9C and my
Hitec Prism 7X. If I go with the XPS standard and want to move to an EVO,
Hitec, JR or something else in the future, my XPS receivers would work with
those transmitters. The fast reboot of their receivers and the promise of two
way communications between receiver and transmitter is very attractive.

I like that Spektrum has such a large user base, as there IS safety in numbers.
However that could be a lock out issue looming for the future. And they don't
have a module for my Hitec transmitter. They have full range as well as micro
receivers so they have receivers for each of my planes. With JR on board, this
standard is well established.

I fly a Futaba 9C but do not consider Futaba as one of my likely choices based
on price, availability and the fact that I would be locked in to a Futaba brand
for any transmitter upgrades. Futaba could become the PCM of the 2.4 GHz world,
maybe better but brand specific. That does not interest me at this time.

If I was going to buy today, I would buy Spektrum based on the selection of
receivers and the ability to fit their receivers in my planes. My electric
planes tend to be small and light. Some of my gliders have really tight
fuselages and I will need LOTS of range for the gliders. Spektrum has receivers
that meet these size, and range specs.

Your needs will be different, but I hope this summary is useful in your choice.
They all seem to work well enough to be considered for your next purchase. It
is just a matter of what works best for you.
Last edited by aeajr; Jul 19, 2007 at 10:57 PM. Reason: Original post was missing the first half of the article
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Jul 19, 2007, 01:56 PM
We have a light weight (9g) 6 channel receiver that will be released shortly. We also have a 4 channel micro (under 3 grams in weight) receiver being developed. We will be releasing a 4 channel car receiver and a 12 channel aircraft receiver next month. We should also have end pin versions for all receivers next month. This will give you 10 different receivers to choose from, and of course, dozens of transmitter options.

The most important aspect of any system is its reliability. Right now, we have thousands of units in use world-wide and we will be shipping roughly 10,000 more units overseas next month. I believe that our bi-directional communication (the ability to know if the receiver is getting its data, and if a frequency change needs to occur), fast connection and reboot time, and rugged MIL-SPEC construction make our system the most reliable available.

While it may be true that a radio manufacturer have been in the 2.4GHz business for 15 years, the radio chip manufacturer we use has been in the radio business (including 2.4GHz) for much longer than all competitors combined. Their name is Motorola, perhaps you have heard of them. Our technology has been in use for more than 2 decades, and has been refined and minaturized over the years resulting in what we have today.
Jul 19, 2007, 02:26 PM
Old fart. VAAATSP
d_wheel's Avatar
I have used all 3 systems, and will continue using the DX7 and 6EX until Futaba ships their 14mz module. If it takes too long, I will probably purchase a Spektrum module to tide me over.

The reason I no longer use Xtreme Power is the fact that it only has 1 receiver antenna. Although I used one for many, many flights without any problems whatsoever, I simple feel more secure with the data link knowing there are more than 1 antenna to help eliminate multi path and shading problems.

The reason I will not stay with Spektrum once the Futaba modules are available is the fact that Spektrum chose to go with a non-hopping method. They pick 2 frequencies at boot up, and stay on them regardless of what might pop up later.

So, in my humble opinion, Futaba has the most robust system. They use 2 receiver antennas AND continually hop from frequency to frequency. Spektrum is second because they have 2 receivers to deal with the shading and multi path problems but do not hop off of noisy frequencies. Xtreme Power is third because they do hop to a different frequency if necessary, but only have one receiver antenna.

Later;

D.W.
Jul 19, 2007, 03:23 PM
Inciting Riots
village_idiot's Avatar
What happens when XPS brings out the remoter receiver modules so that you can have at least 2 positions in your craft receiving data. I say at least 2 positions because it is very likely that he could program things to handle up to about 128 devices, be they receivers, telemetry, or anything else that comes along with time.

But you are right, at this point the Futaba does have the advantage.
Jul 19, 2007, 03:50 PM
Registered User
bsoder's Avatar
repost from that other forum whose Name Shall Not Be Mentioned

----

Nice writeup, Ed. I currently own two an XP6102-SPK (conversion) and a DX-6, plus about eight AR6000 receivers. So far I've been pretty happy with the Spektrum stuff, with the exception of the low voltage/BEC problem - I think the 2.4G receivers (all of them not just SPK) have more problems with low voltage than the older 72mhz did.

Personally, I think that the XPS stuff has the most potential. The fact that they're not tied to "old school" thinking helps quite a bit with innovation - the two-way communication potential is very exciting to me. They are apparently working on a couple complete systems - an 8-channel kit for about $200 and a 16-channel (!!!). When these come out I will be looking very seriously at selling off my Spektrum gear. Just imagine having a voltage monitor built into your TX, giving you realtime voltage on your pack... that right there would be enough to sell me on the system.

If they're able to pull it off, I know what I want for Christmas...
Jul 19, 2007, 04:07 PM
Old fart. VAAATSP
d_wheel's Avatar
Quote:
Originally Posted by village_idiot
What happens when XPS brings out the remoter receiver modules so that you can have at least 2 positions in your craft receiving data. I say at least 2 positions because it is very likely that he could program things to handle up to about 128 devices, be they receivers, telemetry, or anything else that comes along with time.

But you are right, at this point the Futaba does have the advantage.
At that time they will move past Spektrum in my estimation. When the telemetry AND antenna diversity both comes on line, they might very well be at the front of the pack!

Later;

D.W.
Jul 19, 2007, 04:30 PM
Proud member of LISF and ESL
Quote:
Originally Posted by d_wheel
At that time they will move past Spektrum in my estimation. When the telemetry AND antenna diversity both comes on line, they might very well be at the front of the pack!

Later;

D.W.
And so it is with all technology. They jump and leap over and pass each other almost monthly. The top dog today is trailing the pack in three months only to take lead again 3 months later.

As users, do we care? Some will and some won't.

Do we buy based on what is out today or what we believe might be out tomorrow? Each person places value differently.

I gave you my assessment in the article BUT I am not buying today. I probably won't buy till Christmas. So, what goodies will be out then and how will that influence me?

What will my buddies have between now and then and how will THAT influence me?

I know a lot of people who have Spektrum and they are all happy. But would they be more happy if they had XPS or Futaba? Who knows?

If I show up with an XPS, since I am an instructor, will all the new guys follow me? Who knows?

Isn't this fun?
Jul 19, 2007, 04:31 PM
Registered User
bsoder's Avatar
I care about telemetry. No one other than XPS has said anything about that.
Jul 19, 2007, 05:25 PM
BANNED!!!
soholingo's Avatar
Good Stuff... I have decided on Spektrum too... because I fly sailplanes and they large collection of receivers spektrum currently has.

J
Jul 19, 2007, 05:40 PM
Registered User
Quote:
Originally Posted by d_wheel
The reason I will not stay with Spektrum once the Futaba modules are available is the fact that Spektrum chose to go with a non-hopping method. They pick 2 frequencies at boot up, and stay on them regardless of what might pop up later.
I think you misunderstand Spektrum's choice of technology. My understanding is that they don't use Frequency Hopping because they use Direct Sequence instead. Google for Direct Sequence Spread Spectrum (or DSSS for short). It's no worse than frequency hopping (FHSS). The difference is frequency hopping is a simpler concept for a layman to understand. DSSS requires a tertiary degree in math to understand. But basically DSSS doesn't need to hop because it's transmitting on hundreds of frequencies simultaneously!
Jul 19, 2007, 05:58 PM
Old fart. VAAATSP
d_wheel's Avatar
Quote:
Originally Posted by aragon
But basically DSSS doesn't need to hop because it's transmitting on hundreds of frequencies simultaneously!
So, is all this advertising saying they are using 2 frequencies just hype?

Later;

D.w.
Jul 19, 2007, 06:15 PM
Registered User
Their air systems occupy two channels at a time. Each channel is approximately 1 MHz wide. Existing 72 MHz channels are 10 KHz wide (0.01 MHz) and RC systems don't even use all that bandwidth. The huge excess of unused bandwidth in a 1 MHz wide DSSS/FHSS channel is one reason why the systems are so immune to interference.

The spare channel that Spektrum air systems occupy is a just an extra fail safe in case something goes very bad with one. If you look at their surface systems they only occupy one channel, but are still very immune to interference.
Jul 19, 2007, 07:17 PM
Registered User
Quote:
Originally Posted by village_idiot
What happens when XPS brings out the remoter receiver modules so that you can have at least 2 positions in your craft receiving data.
This is what Im waiting for..Although Im sure the single rx antenna works, I just feel more comfortable with a second satellite antenna...hopefully this will come soon.
Jul 19, 2007, 07:44 PM
PNF
infopimp's Avatar
Seems a little surprising to me that Hitec is absent from the list.
Jul 19, 2007, 08:04 PM
Proud member of LISF and ESL
It is surprising to all of us that Hitec is missing. They said they were coming out with something a year ago, but nothing yet, that I know of.


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