Spread spectrum radios
 

I have been out of the hobby for a few years, and am planning on getting back into things. What exactly is "spread spectrum' technology? How does it work

RE: Spread spectrum radios
 

Not sure how it works, but there radios that dont use Crystals and you never have to worry about frequencies. They like jumps from frequencies instantanously, so you never have issues.

RE: Spread spectrum radios
 

From what I have read the radio is less prone to interference and no more need for frequency pins because you will not be flying on a channel. That means you can show up at the field and turn on your transmitter without fear of causing problems for someone else and vice versa.

More info here:
http://www.spektrumrc.com/DSM/Technology.aspx

and RC specific details at their main site:
http://www.spektrumrc.com

RE: Spread spectrum radios
 

Thanks for the replies!
I'll have to check into this. I appreciate the links, too. :)

RE: Spread spectrum radios
 

One issue is the reciever is matched to the transmitter, rather than to a channel so you won't be able to use the radio with any standard receivers that you may al lready have. I am not sure what you have to do if you want to get more recievers if you have more than one plane. The mounting is also a bit more involved because the setup actually uses 2 recievers in the plane.[8D]

RE: Spread spectrum radios
 

You also cant have your cell on while ur flying. Last week a guy at my field had a spectrum and a new plane. He let one of the other members fly but he said you had to turn your cell phone off before you fly because it causes problems.

Not many people at my field have a spectrum so i dont know a lot about them but it kind of sucks that you cant have your phone on while your flying but it is cool you dont have to worry about channels.

RE: Spread spectrum radios
 

UM...

That cell phone thing is not true

RE: Spread spectrum radios
 

Fastsky all you have to do is buy a new RX and bind it to the transmitter. the Great feature of the DX7 (don't know if the DX6 has this option) is that it if you don't have the right model selected on the TX it won't work. where with all the 72 mhz cpu radios I know of it will work using the wrong model setup.

RE: Spread spectrum radios
 

I don't know about the cellphone thing, supposedly Horizon has tested most scenarios and nothing so far has caused problems. I got a DVD from Horizon that goes into great detail about how Spread Spectrum works. The basics are these:

It operates on 2.4 GHz (gigahertz) rather than 72 MHz. 2.4 is the same band that medical equipment in hospitals as well as some cordless phones transmits on. FCC restricts the output for DSS transmitters to 1 watt, and the biggest hurdle toward getting it to work for r/c planes was the signal strength at any kind of range. The dual receiver system ussed helped solve this. DSS is immune to RF interference from gasoline engine ignition systems, as well as metal-to-metal vibration RF. When you mount the Rx in the plane (actually two Rx's connected with a 6 inch pigtail), one has its antennas 90 degrees to the other's, so they get a slightly different "picture" of the signal. The antennas, BTW, are only about 2 inches long, so you no longer have to worry about routing a long antenna wire.

When you turn on the Tx, it scans the entire 2.4 band and selects two unused "channels" and locks onto them before it will transmit. This is why you don't have to use the pinboard, or frequency control with 2.4 GHz. Each radio that gets turned on will not transmit until it has found an unused channel and locks onto it. The receiver has to be "bound" to the transmitter in a procedure you perform when setting up the radio; when this is done, the Rx will ONLY respond to signals sent from the Tx it is bound to. If you have several planes in your radio (the DX-7 has a 20 model memory), each Rx has to be bound to the Tx only once. When you select the plane from your Tx menu, only that plane's Rx will respond, so it is impossible to fly the wrong plane.

I got my registration info for Joe Nall in the mail the other day, and they give quite a bit of attention to using DSS at Tripletree this year. They say that up to 40 planes can fly in a single area on DSS before the band is full. They will still require Tx impound, but DSS doesn't have to use the pinboard system. With only 7 flight stations in use, ther will be NO problems with too many planes in the system.

I'd recommend going to Horizon's website and requesting the DVD about Spektrum.

RE: Spread spectrum radios
 

They don't all take more involved mounting or have 2 separate RX
http://www.towerhobbies.com/rcwnews/...-futk6900.html

RE: Spread spectrum radios
 

Thats what the guy that had the radio said. He told the guy that was about to fly the plane that he needed to turn his phone off or it would cause problems. He said it only happened if you were next to the radio. I dont know maybe it was just his tx/rx i dont know.

RE: Spread spectrum radios
 

G'day Mate,
The cell phone thing is true, but not because it causes radio interference problems, but cell phones, if used within 3 meters of the TX, have been known to scramble the memory of TX's, any computer TX, so it can be a problem with ALL computerised Transmitters, makes no difference what frequency band they are on.
So the rule here is, NO Cells phones to be left on, within 15 meters of the pitts.
Then no problem.

RE: Spread spectrum radios
 

I have a bridge in New Jersey I'm selling real cheap too. If you buy that story, you'll buy the bridge for sure.:D Do you cook your dinner in that crock?

RE: Spread spectrum radios
 

Ive never heard of the cell phone thing .... I allways have my cell in the pitt area and noone has yelled at me yet :D

RE: Spread spectrum radios
 

Alan,

I am sometimes forced to fly while talking on my cell phone, (I sometimes smeak a quickie in during work, who doesn't). Please, unless you have some way of backing-up these claims, don't post such garbage in the beginners forum.

That rule sounds like it was made to keep people's cell phones from disturbing the weekday crowd.

There is no such issue with cell phones and airplane transmitters, period.

RE: Spread spectrum radios
 

It's not garbage if he heard it from someone who thinks their cell phone screwed up their TX. Hearsay is the worst enemy.

Go a little easier guys. Alan is a good, contributing member. No one is right all the time.

RE: Spread spectrum radios
 

I have had it happen to me! I had a newbies plane secured and was running in the engine for him. I had the engine at an idle when the new guys friend walked up to watch. When he came within about 5 feet of us, the throttle started jumping all over the place. I was watching the engine rev up and down trying to figure out what was happening when I looked over and saw the guy had a cell phone. I asked him if it was on and he said that it was. I had him step back a few feet and the interference quit. I don't know what type or brand of cell phone he had and don't know if it makes any difference but our new club rule is ". No cell phones within 20 feet of any aircraft!"[8D]

RE: Spread spectrum radios
 

This might be the older Nextel phones. I know when I used mine a while back for work, any speakers within 20 feet would go haywire.

RE: Spread spectrum radios
 

If a cell phone bothers an R/C plane, something is wrong. If all components are functioning properly this should not happen. Spurious signal radiation of some type.

RE: Spread spectrum radios
 

I always have my phone with me and it does not bother my planes or anyone elses.

RE: Spread spectrum radios
 

A couple of items:
The DX6 does not have the safety mechanism that makes it not work with the wrong model memory selected. Crashed my mini Funtana that way!!

Also, the recievers that came with the DX6 had dual receivers built into the same package. It just had two antennas coming out at right angles to each other.

Finally, Spektrum just announced (last week) their module for JR and Futaba radios. Now you can swap out the crystal pack and antenna and your regular TX is now a DSS system. More info at: [link=http://www.spektrumrc.com/]Spektrum RC[/link].

--
Tom

RE: Spread spectrum radios
 

Can it be used with any futaba radio like a 7 channel cap??

RE: Spread spectrum radios
 

From the website:

One of the modules is compatible with the following Futaba Radios:

7U Series Radios
9C Series Radios
9Z Series Radios
FN Series Radios

And the other Futaba module is compatible with Futaba 12Z or 14MZ Radio Systems.

--
Tom

RE: Spread spectrum radios
 

There are a lot of other devices used in the 2.4 gHz range than phones and med equipment. Microwaves. Cordless keyboards. Wireless Internet base stations and computers. Mixing all that around causes havoc in a household, and that is only a partial list of devices.

RE: Spread spectrum radios
 

G'day All,
Read this Procedure, it is from our governing body here in Australia, the MAAA.
Then tell me I'm WRONG!!!!!!!!!!!!!!!!!!
http://www.maaa.asn.au/mop/policy/MO...ept%202004.pdf