You're claiming collisions can't or don't happen?

ORIGINAL: onewasp

bobzilla

True or false?

Originally Posted by hilgert
Actually, the AR7000 (and the AR6100 as well I believe) actually send back a very low-power signal to the DX7 to let it know it is a DSM2 RX, and the TX adjusts power usage accordingly (since the DSM2 transmission protocol must be more efficient in some manner, probably due to it's higher speed as it would need to be "on" less of the time). The AR6000 does not send anything back, so the DX7 stays in DSM (and not DSM2) mode.

If you guessed (I'm using the term advisedly) True then you are CORRECT!
The highest levels at Spektrum reviewed this----just as copied here and said "True".

I lost because I said no!!

Live and learn--------so now I have learned.

This is not intended as a "Gotcha" nor is it in any way intended to cast myself in any role other than 'Messenger'. Nor did I have Hilgert's OK to re-post his correction to a post I had made on another thread/site. I feel that Hilgert would go along with it if I had asked him-----at least I'm counting on it.

ORIGINAL: bobzilla

Spektum is NOT 2-way. The transmitter only transmits and the receiver only listens.


What is Model Match?
Model Match (patent pending) prevents the pilot from flying a model using the wrong memory. During binding (the process of teaching the receiver the specific code of the transmitter) the receiver actually learns and remembers the specific model memory that is selected during binding. Later if the system is turned on and a different model memory in the transmitter is selected, the system will not operate. This prevents the disastrous issue of trying to fly a model using the wrong model memory. Simply selecting the correct model in model memory will cause the system to connect.


What is DSM?
DSM or Digital Spektrum Modulation is Spektrum's proprietary method of implementing 2.4GHz spread spectrum technology for the R/C industry. DSM divides the 2.4Ghz band into 80 individual channels (frequencies) and incorporates direct sequence spread spectrum with an imbedded GUID (Globally Unique Identifier) code. DSM has been painstakingly optimized by our engineers for R/C surface and aircraft use, offering the most robust RF link in the industry.

What happens if the band is full (80 users for surface or 40 users for aircraft) and I turn on my transmitter?
In the unlikely event that all channels are occupied, the next transmitter will scan the band indefinitely until open channels are available. The transmitter will then acquire the channel(s) and begin transmitting. Only then will the system connect.

What happens if two transmitters are on the same frequency?
To be FCC legal, all 2.4Ghz devices must incorporate a collision avoidance system that prevents the system from transmitting on an already occupied frequency. The chance of two transmitters occupying the same frequency is highly unlikely. If two transmitters should somehow end up on the same frequency, other safeguards, such as the GUID and proprietary time base coding, will prevent interference. Of course, with the aircraft system, the transmitter is transmitting on two frequencies simultaneously. The odds of two transmitters transmitting on the same two frequencies is even, more unlikely but again, should this happen, other safe guards will prevent interference.


and as far as two receivers..

The receiver has an extra part attached to it. What does this part do?
The AR7000 incorporates two receivers; an internal receiver is located on the main board and the extra part your referring to is actually an external receiver. Mounting the external receiver in a slightly different location with it's antenna oriented in a different direction greatly improves the RF link in difficult environments.

and for a quick DUAL LINK explaination

What is Dual Link?
Dual Link is a breakthrough, patented feature that was first incorporated in the DX6 aircraft system. Dual Link offers the security of two-path RF redundancy. The AR6000 is actually two receivers in one. The DX6 transmitter transmits on two frequencies simultaneously while the receiver receives and decodes both sets of information. Should one signal be blocked or corrupted or should one receiver malfunction in flight, the other frequency or receiver will take over. Dual Link offers the security of having two radios operating simultaneously on two separate frequencies.

ORIGINAL: chrisF test pilot

Regardless of the boot process from an operational standpoint you have to consider the Spektrum a one way system. There is no communication back to the Tx during operation and there is no error correction. So to sum it up you could say it is a one way system that uses two way communication to determine RX type.

ORIGINAL: dirtybird

Its not a dedicated park flier but the functions it provides will likely confine it there. A flier used to a computer radio will not buy it.

ORIGINAL: bobzilla

Here is a statement about the difference that Futaba and Spektrum utilize:

FHSS VS. DSSS
There are two primary types of Spread Spectrum technology- Frequency Hopping (FHSS)[FUTABA] and Direct Sequencing (DSSS). FHSS systems transmit a narrow band signal and rapidly jump from one frequency to the next spending a few milliseconds on each frequency. DSSS systems transmit on a single selected frequency but on a very wide band. Only a small portion of that band is used for specially encoded information. Originally, Spektrum engineers started their development with FHSS-based systems because they were relatively easy and inexpensive to develop. However, it was soon discovered that FHSS had several limitations that would prevent it from being the optimal solution for RC.

While more difficult and costly to develop, Spektrum engineers began experimenting with Direct Sequencing Spread Spectrum and optimized the modulation scheme to overcome critical response and re-link issues. In addition, DSSS offered 18dB increase of processing gain for significant improvements in range. With years of development and testing the DSSS modulation scheme was optimized for RC car use and Spektrum's DSM 2.4GHz Spread Spectrum Technology was born.


Looks like the FUTABA engineers did not reach the same conclusion that SPEKTRUM reached concerning pro-con's of each.

I really could care less which to buy..only I want the system to WORK and be relatively in-expensive.

Bobz

ORIGINAL: nonstoprc

So which scheme is better: Futaba's FHSS or Spektrum's DSSS?

ORIGINAL: ALbert.S

Check the spelling speKtrum speCtrum

ORIGINAL: rcguy!

Thread title clearly shows "SPEKTRUM"

ORIGINAL: aeajr

I find this statement odd. What do you define as a computer radio?

The 6 EX is a computer radio. It is the 2.4 GHz version of the Futaba 6 EXAS. It contains model memories, flapperons, free surface mixes, expo and other features common to computer radios, and not found on standard radios.

It is a full range radio, which in my book means at least 3000 feet and more likely a mile. I have not seen a specific range rating. So you can fly anything that is AMA legal.

There are thousands of people who fly planes of all sizes on standard 4 channel radios. I go down to the local glow field and a lot of the pilots use standard 4 channel radios. So, if they can do that on a 4 channel standard radio, why can't they do it on a 6 channel comptuer radio?

The only difference between giant scale planes and smaller planes is the size. People were flying giant scale planes on standard radios long before there were computer radios.

In relation to giant scale, my only concern here would be whether the receiver can handle the amperage needed to work those big servos. But many giant scale pilots have externally powered boxes to handle that drain rather than try to run it through the receiver. I am sure that would work well here as well.

This radio can fly any plane of any size that uses standard R/E/A/F/Retract features. In other words it has 6 channels so it can control six functions, just like any other 6 channel radio. And it can remember the settings for multiple models, just like any other computer radio.

It also has the ability to support aileron control on separate channels. It also has two free mixers that allow you to mix any two channels. Good for flap to elevator compensation I would bet. Or Rudder to Aileron mixing. It might even allow you to do separate channels for flaps if you don't have retracts. None of my 18 planes, ranging from 30 inch to 134 inch wing spans, have retracts.

Now, if you feel you like to have more features, that is fine, or if you NEED more features, that is fine too. That is why there are higher end radios. However, to say that you can only fly parkflyers on a 6 channel comptuer radio is absurd. In fact the Futaba 6EX on 2.5 GHz or 72 MHz is probably all the radio that most sport flyers will ever need.

I have a Futaba 9C which I use for my scale sailplanes, full house sailplanes, RES sailplanes, hand launch gliders, slope gliders and small electrics. But I use it for convenience and enhancement, not because I NEED it to fly these planes. I could fly them all on a standard 4 or 6 channel radio if I wish.

ORIGINAL: nonstoprc

So which scheme is better: Futaba's FHSS or Spektrum's DSSS?

Intuitively, hopping can lead to collision and hence to hopping more. The end result is that the response time on the receiver side can become slow when the frequency is crowded.

Am I right?

--qc

It is unlikely there is a specific number limit on the Futaba set.