Futaba Fasst vs Spektrum radio link

[jonkoppisch]

The way that they are saying is that if you have a spike, or whatever you want to call it that takes the voltage down below the reset amount for a split second will cause the receiver to reboot which has cost several people their planes? I would think that it would be an advantage to have the lowest possible operating voltage on your receiver to try and avoid this, NOT SAYING IGNORE YOUR BATTERIES! Not that you should need it!!! Not saying that you're going to try and be flying around at 3.1 volts!! What I've been led to believe though, is that if your using digital servos etc and your battery for some reason isn't at full capacity, you suddenly put a large strain on the battery causing it to dip below the reset voltage, the receiver will reset locking you out for X amount of time. That extra 1/2 volt before reset could end up being a plane saver??

Nowhere did I say that you could be flying around at 3.1 volts??? That was uncalled for but whatever...

[wildhare]

I have been using Spektrum since it came out, it works great for me and i am impressed with their product offerings like the new AR9100. I have decided to commit to this technology and have ordered a X9303 transmitter.

Before the DX7 came out I used Futaba transmitters exclusively along with mostly Futaba receivers. I was completely happy with Futaba. I have no axe to grind with Futaba.

I think the transmitter technologies are roughly equivalent. These are two completely different ways of doing the same thing. But I think the Spektrum/JR receiver approch is much better.

There must be some reason why Spektrum developed the satellite receiver concept. Futaba does not use this and I am thinking this may be the source of their delays in delivering product.

Even if Futaba does work as well, Spektrum is here now and I want to move forward.

TF

[dick hanson]

Relax --my point is that the argument of 3.5V vs 3.1 V as being a point , hardly worth the effort
Why?
If you do some hands on testing of batteries - as needed to get proper operation with high power servos -- you will see that any setup worth having will not see under 4 volts unless the batt is going dead.
Futrther - many of the so called failures with Spektrum were with small electric powered models which had ESC/BEC problems-,oftendue to excessive motor loads and P poor batteries . and often as not the user had no clue as to the relationship of powerbattery/ BEC voltage drop etc..
Also there were a jilion of these on the market and NO --count em NO other 2,4 setups running . So the instant knee jerk reaction was " the Spektrum don't work"---
I have 4 foamies with 6100rx from a 5 ounce to a 18 ounce and batts from 380 mah to 2100 - I flog the crap out of all of these and all will fly as far as you can see.

So why do I scoff at some of the so called tests I see?
Simple - I can find no FACTS to back em up-

[hillmanr2]

Thank you fellows, I really appreciate it They are both the same it would seem. I have 2 kids that fly on Jr radios, I guess my only other question is if the JR 2.4 is buddy box compatible with 72 MHz radios. I assume they would be but we know what happens when we assume .
I would go with either the Futaba 12 channel soon to be released JR 12 channel, unless the JR 12channel programing is the same as the 9303. Then I will order a JR 9303 and copy my models from my 72 Mhz 9303 .

[sweetpea]

They should be as your 2nd radio does not transmit a signal.

[Pale Rider]

	Quote: Originally Posted by jonkoppisch
	The way that they are saying is that if you have a spike, or whatever you want to call it that takes the voltage down below the reset amount for a split second will cause the receiver to reboot which has cost several people their planes? I would think that it would be an advantage to have the lowest possible operating voltage on your receiver to try and avoid this, NOT SAYING IGNORE YOUR BATTERIES! Not that you should need it!!! Not saying that you're going to try and be flying around at 3.1 volts!! What I've been led to believe though, is that if your using digital servos etc and your battery for some reason isn't at full capacity, you suddenly put a large strain on the battery causing it to dip below the reset voltage, the receiver will reset locking you out for X amount of time. That extra 1/2 volt before reset could end up being a plane saver?? .

All of that is 100% accurate--but again if you have the right power setup for your particular plane, it is a non-issue IMO...Thats why its even more important to know how many mah's you use on each flight and to check the voltage on each flight..thats whats so great about the A123's they can handle 40A without even a second thought--not trying to say that sh-t doesn't happen but if you start with the right sized batteries, you are going to be ahead in the game.

[GooseF22]

my 2c.

Actually my favorite radio was the super 8 futaba so I bought the spektrum module for it. so Im flying both!!.

FSS versus DSS.

The benefit of FSS is that it is narrow bandwidth signals an allows for discreet signals. the problem is noise. the Benefit of FSS is the channels are virtually unlimited. That is both a disadvantage and an advantage. FSS frequency hopping has more solutions, but in a broadband noise environment, hopping slows down if a frequency is noisy. timing is critical for the hopping scheme.

If the threshold of noise is high, frequency hopping is difficult. spektrum looked at this technology before diving into to sequencing. The advantage of DSS is that as the noise threshold climbs, the speed doensn't take a hit. you are either locked or you are not. Signal strength is irrelevant. I chose spektrum because I can control the diversity, and because it was matured first. AFter taking it to the lab and disecting the signal, I was pleased with it the relative under the curve power and frequency stability, and its speed.

All that said, both will work fine, but I chose DSS because as it gets more popular, I didn't feel that I would take a speed hit, and that with extra receivers, longer range or redundancy was available.

Remember, I was a futuba guy before, and I still love that old super 8 radio. It will be my main radio until the 12x

[jonkoppisch]

Here's an example of what I was referring to.. http://www.rcuniverse.com/forum/fb.asp?m=6489050 I don't know how the other 2.4 systems would have handled it but with the reports of loosing planes because of low batteries I would guess not well..

Added: I own & use the spektrum and xps systems. I have lost a plane with the xps, but not due to battery.. Now it's only a park flier system for me. That's why I say any little advantage helps. The spektrum is the dx6 and it's worked great!

[gareth.ky]

	Quote: Originally Posted by tommy321
	Hey Russ! I've wondered the same thing as you. Which is better, frequency hopping? or DSM? After talking to some electrical Engineers I know, I they've said that they can't really say which one would be better without learning of the details and specifics of how each modulation is actually implemented. And these are probably carefully guarded secrets. However, the general consensus was that any differences would be negligible until you get so many systems running that people start falling out of the sky. Sorry I can't be of much more help... I'll keep my ears open though. Tom

I would tend to agree that we don't know enough about wither radio to tell if one is "better" than the other. The is in the details.

As far as I can tell the FASST system must have a max transmit power of 1/10th of 1 watt while the Spektrum can have a max power of 1 watt. At least thats what the FCC rules state. Actual power output, who knows?

The FASST antennas are longer (looks like full wave length) and there are two of them. Spektrum has multiple redundant Rx modules that diversify the receiver environment. They also have the lightest and smallest Rx's which is great for indoor.

The FASST system has a lot of marketing speak coming along with it. One term I am going to take a stab at is "Pre-Vision". I believe this is a reference to dynamic hop-set modification. The Tx will drop channels from the hop set if it detects that there another signal on that channel. Hop sets can't get smaller than 16 channels, again, thats an FCC thing.

Timing is critical for hopping systems BUT that probably wont be an issue here. First we don't run the Tx and Rx for long enough for clock drift to be a problem. Second if they do truly random hopping then the Rx doesn't know what channel is next in the sequence so it doesn't matter. If not then we should look for something in the communication stream that relays the new hop set to the other end.

One feature that FASST does not support is Model Memmory Matching. I know that has saved my bacon a couple of times with Spektrum so I want that in my radio.

I have some friends around here that fly the FASST system and are really impressed with it. I have also spoken with the local hobby shop that sells both systems. They claim that more issues have been reported by customers of Spektrum than FASST. They also claim they have sold more FASST systems than Spektrum. I take this with a grain of slat though because they are sponsored by Team Orange.

I see Spektrum/JR innovating and solving real problems that I have with radios and not all of them are related to signal transmission.

For my next radio I'm on the fence and it may boil down to feature set of the radio and price. I have a DX7 now and I don't have a compelling reason to upgrade at the moment.

[somethnextra]

I have experience with the DX7 and the 6EX/9C with TM-7. I have used both systems in VERY adverse RF environments. Both work well. However, transmitter technology and voltage requirements aside, the FASST performed better.

The reason that Spektrum has a satellite rx is to provide antenna diversity. In other words, it "sees" a different RF environment because of its different orientation. The FASST receivers do the same thing by providing two antennas but in one package. If you look at the instructions, they explain that you should orient the two antennas with 90 deg difference between the two. This ensures that you are receiving in every possible direction and that there are no blind spots (dead zones) as you would find in a traditional one antenna setup.

The actual antennas on FASST rx's are the same length as Spektrum's. They are just extended via coax to isolate them from the rx's circuit board. This provides a better RF environment.

The FASST technology also offers "pre-vision". If a 2.4 channel is in use, it eliminates it from the hopping scheme. Thus reducing the chance of interference. This process is constantly updated so that as soon as a channel is not in use, it is added back to the scheme.

The linking process is also easier with FASST ("binding" for you Spektrum users) since you don't need the switch that came with the radio. Not sure but hopefully this has changed on the newer JR radios though.

I have been using FASST since it first came out and have found it to be very reliable. I won't put anything else in my airplanes now.

[wildhare]

	Quote: Originally Posted by somethnextra
	The linking process is also easier with FASST ("binding" for you Spektrum users) since you don't need the switch that came with the radio. Not sure but hopefully this has changed on the newer JR radios though.

To bind on a spektrum you only need to have signal and ground wires flowing to your charge jack so that the signal line can be tied to ground. This is true in every switch I have ever used, no need to use the original switch.

TF

[somethnextra]

Yeah I was trying to allude to the fact that there aren't any binding plugs to lose with FASST but it came out wrong One more thing I left out.

Pre-vision also applies error correction on the rx end. It can perform a logic check by comparing the newest packet to the previous packet. If it doesn't follow in sequence and the values are way off of what they should be, the rx eliminates this packet and keeps the servos where they are until a good packet is received. This will most likely be 0.002 seconds later when the next packet comes in. Kind of like fail safe but instead of being based on signal to noise its actually based on the accuracy of the information that makes it to the receiver.