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Why do Spectrum radios use Satellite Recievers and Futaba radios do not?

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Why do Spectrum radios use Satellite Recievers and Futaba radios do not?

Old 10-24-2013, 11:50 AM
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dksnyder
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Default Why do Spectrum radios use Satellite Recievers and Futaba radios do not?

Why do Spectrum radios use Satellite Recievers and Futaba radios do not?

I am a Futaba user, and all this talk about Satellite and/or Remote receivers is new to me.....
I don't believe any Futaba radios/receivers require Satellite receivers. Is this correct??

Why do Spectrum radios use/require Satellite receivers?
Do ALL Spectrum (and JR??) radios use Satellite receivers?

Why the seemingly significant difference?
It appears that the spectrum receivers need additional antennas for satisfactory reception.

Are these Satellite receivers just redundant antennas? (and not actually redundant recievers??)

Whenever I hear a Spectrum radio user talking to a Futaba user it just turns into confusion....
I'm confused too!!!

Don
Old 10-24-2013, 11:59 AM
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Good question, because everybody else only uses 1 receiver and yet I have seen and read about Spectrum users losing control and browning out etc. more than any other radio.
Old 10-24-2013, 05:32 PM
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SkidMan
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No, not all Spektrum receivers use redundant receivers. Some, especially receivers targeted for the park flyer market, use a single receiver.

Yes. They actually are independent receivers with their own antennas. The primary receiver that controls the servos only uses signals from receivers that have received a given frame without error.

The polarization of antennas makes a difference with the higher frequencies of the 2.4 GHz band. Having more than one receiver allows the ability to have receivers in multiple orientations and locations.

Yes. There is a holy war between Spektrum and Futaba fanboys. It is essentially impossible to have an educated conversation comparing them on the forums. I suggest weighing the value of people's input based upon the maturity of their response.

Appropriate battery systems are essential with either make of receiver. There have been too many situations where people have tried to use 4-cell AA-sized NiMh batteries on planes with many servos, higher powered servos, or servos binding, where the inability of the NiMh batteries to sustain an adequate voltage under the current load has caused brown outs.

Punchline: IMHO the 2.4 GHz digital transmitters and receivers from Futaba, Spektrum, and several other companies are highly reliable. Particularly if you are a new pilot, check to see what is primarily used where you will fly, talk with a couple people, and buy a transmitter that will meet your needs now and for the next couple years. Now that the radio systems are starting to fall in line with Moore's Law it does not make sense to over-buy - New, better, more capable, and less expensive equipment will continuously become available.

Paul
Old 10-25-2013, 06:47 AM
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LesUyeda
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" It is essentially impossible to have an educated conversation comparing them on the forums. "

Sort of like arguing politics and/or religion:-))))))))))))))))

Les
Old 10-25-2013, 11:27 AM
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dksnyder
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Thanks for the reply, Paul

I guess the remote "receivers" used by Spectum are technically "receivers", but they are not used for controlling servos.
I think they are used to provide redundant signals from differently oriented antennas, so as to provide another option for "errorless frame rate", as you mentioned.
There is really no "redundant" receiver..... if the receiver controlling the servos fails..... all is losy, no matter how many "satellite Receivers" are connected. (I think!!)

I just wonder why Futaba does not think the redundant signal info from a "Satellite Receiver" is necessary..... (as does Spectrum)
Does this indicate that the Spectrum system is not as "robust" as Futaba?
Does it indicate that the Futaba system (without the "Satellite) is not as "robust as Spectrum??

Actually, I think the two systems are pretty equivalent....
and, I'm sure both provide more than adequate range & response!!
Old 10-25-2013, 11:40 AM
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Two antennas, whether a satellite and one on the main receibver or both on the main receiver board, are somewhat more reliable than any receiver with a single antenna. Since the higher frequencies (as 2.4GHz is) are more easily deflected or shielded than the lower frequencies are and are more prone to disruption by the polarization of the signal. By having two antennas with their orientation at 90 degrees to one another, the receiver get the transmitted signal more often as the polarization is changed anytime the receiver antennas change position relative to the transmitter antenna but one or the other is in the more optimum position at all times. A single antenna can lose most of the signal if the polarization is at it's worst orientation which is when the transmitting antenna is pointing straight at the receiver and the receiver's antenna is pointing at the transmitter antenna.
Old 10-25-2013, 04:31 PM
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Other brands cannot use the same implementation as Spektrum because we patented it. The have to go by other means to try to achieve comparable performance.

Andy
Old 10-25-2013, 04:53 PM
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chuckk2
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How in the heck can you patent space diversity receivers? They have been around for years! Just not in consumer equipment!
I suppose when you combine space diversity along with antenna orientation, along with channel "hopping" and algorithms, it is possible.
"Computerization" has made many things that were once difficult quite easy (in principal, anyway).

One of the uses I remember had to do with radar and finding the exact position of an aircraft, even when the aircraft had equipment that was intended
to interfere with such efforts. By making the ground or airborne radar transmitter(s) slightly frequency agile, and changing exactly when the pulses were sent, along with
receivers at different locations, it was possible to obtain aircraft tracking information, and negate most of the jamming.
Old 10-26-2013, 08:42 AM
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I think that Futaba does use diversity receivers. The two wires coming out of the Futaba receiver are actually each separate antennas, not a single dipole. They are each sleeve antennas. Inside the box are two receivers. I think. I might be wrong.

Spectrum just took it a step further by adding remote receivers. Why they felt they needed this while Futaba did not I can only guess.

Last edited by JPMacG; 10-26-2013 at 09:12 AM. Reason: Original post was too inflamatory
Old 10-26-2013, 08:58 AM
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[QUOTE=JPMacG;11647276]
If I were a jaded person I might say that Spectrum realized they had a potential link budget problem and added additional receivers as a band aid.[/QUOTE

I find it interesting that JR has moved away from the Satellite receivers and now use the (2) separate antenna / single receiver system similar to most other manufacturers. Spectrum people would probably say they did it for licensing reasons as they move away from the Spectrum RF system. My guess is they found the separate receivers to be just another source of potential problems and chose to simplify their own designs.
Old 10-26-2013, 11:12 AM
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Rodney
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Originally Posted by JPMacG View Post
I think that Futaba does use diversity receivers. The two wires coming out of the Futaba receiver are actually each separate antennas, not a single dipole. They are each sleeve antennas. Inside the box are two receivers. I think. I might be wrong.

Spectrum just took it a step further by adding remote receivers. Why they felt they needed this while Futaba did not I can only guess.

I'm reasonably sure you are correct, even though both antennas come off one board, there are two independent circuits (two receivers) on the board. From my somewhat limited source of info, it appears that Futaba has always been the leader on the 2.4GHz area, after all they have had about 30 or 40 years more experience and military backup than the newcommers such as JR. Spectrum and others although the newcommers are very good at duplicating Futaba's performance, especially FrSky with outstanding success. Lucky us, no matter what brand we buy, we get some very good performance.
Old 10-26-2013, 11:13 AM
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Is that why they were so late to the party?

Andy
Old 10-26-2013, 11:32 AM
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Long before 2.4 was dreamed of for consumer RC use, I regularly flew several brands of equipment. Like today, most were very dependable so I'm not a brand snob or fan boy. I was an early adopter of JR and Hitec digital servos but was burned bad (very frustrated) by what I called "JR's servo of the month club". As problems developed and there were many, I would receive replacement servos only to notice that the only thing the same in the replacement servo was the label! I mention this only to illustrate that being first to the party (first in the market) is not always a good thing. With regards to the servos, Futaba digital servos didn't show up in the market for quite some time after JR introduced them and I don't remember Futaba having anywhere near the problems that JR had. I'm sure that Futaba and other companies learned from JR's mistakes.

Being first to the party can lock you into choices that are hard to get away from later on. Perhaps that is the case with Specktrum and JR satellite receivers. Coming from an RF background, I never quite understood why they went that route they did with the remote receivers but once the choice was made, economics of production probably locked them into the choice for some time to come. The system has certainly not proven itself to be any better than the dual antenna receivers so common with other companies and now of course from JR as well.

So why did Spectrum go with the remote receivers? I'm sure engineering thought it was the best system at the time. I wasn't there so could certainly never second guess their decisions. It is what it is as they say .......
Old 10-26-2013, 12:33 PM
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i agree
Old 10-26-2013, 02:28 PM
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fragile
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This is why: http://www.youtube.com/watch?v=FazZH...eature=related
Old 10-26-2013, 03:44 PM
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rmh
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Opinion does not mean knowledge of a subject .
2.4 systems for model use are simply 'black magic " for many.
why the widely spaced satellite rx present a much better chance of getting solid info which may otherwise blocked, is not a difficult concept to understand - but some simply don't grasp the concept .
The range capability of a 2.4 is one thing
The ability to insure the signal is not blocked - yet another .
I use on board logging to read what each antenna sees - and contrary to what some may "think" , positioning of the reception points makes a big difference -is some models - in most sport stuff - it may be of little issue .
Battery requirements are still black magic to many as are regulators and BECS.
reading the opinions as to why models crash makes this quite obvious.
battery "tests" and BEC tests seen here -are for the most part ,tests which prove -nothing- and make it appear that failure MUST be a receiver issue .
Seen this over and over and don't expect to see the basic problem change
The basic problem - the user simply does not understand proper use of all the inter related parts of the radio systems
You don't need a background in electronics but if you want to avoid problems , spend sometime finding out the problems which can occur if the system is used incorrectly.
Old 10-26-2013, 04:04 PM
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jefflangton
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Ok I'll be the first to spell it right. Spektrum sucks
Old 10-26-2013, 05:12 PM
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rmh
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As noted - opinions have little to do with knowledge
Old 10-26-2013, 05:32 PM
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Well, haven't posted for quite a while but I recall the PCM wars of past and it seems that they have morphed now into the 'redundancy' of having a satellite reciver vs. not......
I have some older, 1st generation Spektrum receivers that made use of the satellite receiver and as an EE myself always thought it a good idea. Of course I haven't flown since 2005, or 2006, can't remember anymore and at the time was in the process of transitioning from 50mhz to 2.4ghz.

Life/the great recession interrupted that transition so I find the need to buy a new radio.......
As an aside I now see a newcomer, or at least to me, TACTIC.....
Old 10-26-2013, 10:24 PM
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Originally Posted by rmh View Post
As noted - opinions have little to do with knowledge
well let me give an opinion that is based in observation. In the last two years at my field I have never seen a single futaba have to be rebinded with the transmitter where as at least once a month I see a JR have to be rebinded. And I have seen a jr rebinded flown act funny and after the plane is down the light is flashing like the bind is not right.

But for me it all comes down to one small thing. One reciever. That is all. No running a separate satalite receiver or two just one receiver that works every time. Simple.
Old 10-26-2013, 10:34 PM
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Well, I've been doing some research for last few hours and it appears to me, given the dual antenna configuration of Futaba and others, that they, Futaba, have integrated the redundant receiver into the same case as the primary and simply use two antennas.......Could be wrong but that makes sense to me as the signal is what's not reliable due to aircraft orientation and it matters not where the receiver is located, just the antenna.
Old 10-27-2013, 03:05 AM
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Originally Posted by raptureboy View Post
Good question, because everybody else only uses 1 receiver and yet I have seen and read about Spectrum users losing control and browning out etc. more than any other radio.
Very well put!
Old 10-27-2013, 03:07 AM
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Originally Posted by SkidMan View Post
No, not all Spektrum receivers use redundant receivers. Some, especially receivers targeted for the park flyer market, use a single receiver.

Yes. They actually are independent receivers with their own antennas. The primary receiver that controls the servos only uses signals from receivers that have received a given frame without error.

The polarization of antennas makes a difference with the higher frequencies of the 2.4 GHz band. Having more than one receiver allows the ability to have receivers in multiple orientations and locations.

Yes. There is a holy war between Spektrum and Futaba fanboys. It is essentially impossible to have an educated conversation comparing them on the forums. I suggest weighing the value of people's input based upon the maturity of their response.

Appropriate battery systems are essential with either make of receiver. There have been too many situations where people have tried to use 4-cell AA-sized NiMh batteries on planes with many servos, higher powered servos, or servos binding, where the inability of the NiMh batteries to sustain an adequate voltage under the current load has caused brown outs.

Punchline: IMHO the 2.4 GHz digital transmitters and receivers from Futaba, Spektrum, and several other companies are highly reliable. Particularly if you are a new pilot, check to see what is primarily used where you will fly, talk with a couple people, and buy a transmitter that will meet your needs now and for the next couple years. Now that the radio systems are starting to fall in line with Moore's Law it does not make sense to over-buy - New, better, more capable, and less expensive equipment will continuously become available.

Paul
Oops, wrong quote in my last post. Sorry.

Very well put Paul. Couldn't have said it any better myself and probably would have said it worse!
Old 10-27-2013, 03:59 AM
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Rob2160
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Originally Posted by skillet92 View Post
well let me give an opinion that is based in observation. In the last two years at my field I have never seen a single futaba have to be rebinded with the transmitter where as at least once a month I see a JR have to be rebinded. And I have seen a jr rebinded flown act funny and after the plane is down the light is flashing like the bind is not right.

But for me it all comes down to one small thing. One reciever. That is all. No running a separate satalite receiver or two just one receiver that works every time. Simple.
Ok, I'll jump In at this point.

I have several Futaba, Spektrum and JR radios and use them all frequently. All my radios have performed flawlessly in over 3 years and more than 10,000 flights in over 60 different planes and Helicopters.

So I have no bias towards any brand and can comment objectively.

I have over 40 planes / helicopters using Spektrum and not once have I ever had to rebind a receiver, and some have been bound for over 3 years and flown over 1000 times.

I am not disputing your claim about others having to rebind their systems, but it has not been my personal experience at all.

With respect, your comment "and after the plane is down the light is flashing like the bind is not right. " tells me that you perhaps do not understand what the flashing lights actually mean.

If it was an orange flashing light it means, 1. the Receiver is in DSM2 mode, and 2, The receiver has sensed a drop in power below its "brown out" level

If it was a RED flashing light it means there was a 'temporary" loss in connection between the TX and the RX.

Now, there is a third possibility that I see all the time with Spektrum users.. if the aircraft lands, and you turn off the receiver then turn it on again, or change flight battery in an electric aircraft with an ESC / BEC WITHOUT turning off the Transmitter, you will get a flashing orange light on a receiver operating in DSM2 mode.. This happens 100% of the time and is completely to be expected.

I have seen several pilots do this and they don't notice the receiver lights flashing until the second landing then scratch their heads wondering what happened.

Watch my video here for a full explanation of the flashing lights, what causes them and what they mean. http://www.youtube.com/watch?v=4_Tbes9f1_c

I don't know the reason why Spektrum use satellites and Futaba do not.. but I know they perform equally well in the air and the real world range is almost identical.

From my own testing, only one of the two antenna on a Futaba receiver needs to see a signal from the Transmitter and the whole system will work.

Likewise, only one of the 3 or 4 antenna in a Spektrum / JR receiver / Satellite arrangement needs to see the TX signal and again, the entire system works..

Spektrum has up to 3 or 4 ears listening for a signal.. Futaba has 2... I'm not saying one is better than the other, because in my experience they all work great.

I have done extensive personal range checks with every transmitter / receiver I own and the best range (by about 15%) was a Spektrum Receiver with a JR11X transmitter.

I have plenty of videos of these range checks If you want to see them click here.

Spektrum do make several receivers in the same form factor as the Futaba Receivers, IE, one single receiver with two antenna, See here

Regardless of brand, you should ensure your airborne power supply to the receiver and Servos is sufficient to provide correct operating voltage under any expected flight situation. Any brand receiver will have problems if the supplied voltage drops too low.

My radios, though this photo is missing a new JR 9503 and another DX6i.

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Last edited by Rob2160; 10-27-2013 at 04:28 AM.
Old 10-27-2013, 04:14 AM
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rmh
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Good info -nicely done -
If only the info needed on sufficient power to the systems were included!

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