JIMF14D

Oh, you did not spend $500 to make a fashion statement like that guy says who has no idea why we went to 2.4ghz but broad brushes all us smart guys!

Another reason:

I can make minor or major ground adjustments to my model set up etc without waiting for my channel to be clear and holding up other people who may be ready to fly on my channel. With the A9 Ican program and make changes at the field without radiating at all.

The reasons are endless but being cool is not one of them.

Jim D.

dbcisco

There are still only 80 channels available in 2.4Ghz and most radios use redundancy which means that no more than 40 aircraft at a time in the same airspace. This is less than the 50 plane limit with FM. Other than big events, I have never seen that many planes at one time, period, let alone in the air.

ram3500-RCU

My Feedback: (221)

I am slowing converting to 2.4 ($$$$$). Reasons are as follows.

- better human-machine link
- more RF resistant (with the gas stuff, I still follow the same install safety procedures as with 72mhz)
- nicer installs without those long antenna wires
- less expensive RXs even for higher end ones (except the top shelf, they are about the same, but you get much more like data log and power management / redundance)
- no channel conflicts at the field
- many flying events are going to 'all 2.4'
- my small electric stuff is now virtually impervious to internal interference.

I am also converting to A123 batteries. Not because they are the 'latest thing', but because they are better.

As long as humans are imperfect, what we produce will be imperfect, but we are making progress.

BarracudaHockey

My Feedback: (11)

Invariably even if there were only 4 people at the field, atleast one of them would be on my channel!

IMAC just means you can fly straight lines! (Just kidding, most of those guys know their stuff)

2.4 isn't "immune" to interference, it just operates well above the freqencies generated by most of the common causes that we see such as metal to metal rubbing.

Are you running a restistor plug?

zac137

Maybe try running a 6.0V battery pack. I have had problems with Spektrum while running 4.8V packs.

Zach

geh3

My Feedback: (84)

I have used FUTABAFASSTsince it came out.... no issues whatsoever... solid as a rock!

nonstoprc

My Feedback: (90)

No. if u do the math, the frequency hopping is better when # of frequency hopped is greater than 2.

TimBle

???

Spektrum and JR users are limited to 40 "in use"Tx at one flying field. Futaba and Hitec are not.
Even Corona can cope with more users.
If flying FAAST, there is no practivcal limit on the number of users within a 3km radius.
DSM uses only 2 channel for its DSSS, whereas Hitec uses 20 and Futaba 36 channel for FHSS. FHSS is where youneed to be with any engine using an ignition coil.

thte problem willcompound itself when .40 size gasoline engones are available. And they are coming FAAST........ (See what i did there...)

TimBle

Exponentially better..

dbcisco

How often have you been in a situation where you needed more than even 40 planes in the sky at once?
As such as a situation is pretty rare, then even FM has enough channels. This, at least, is no reason to dump FM.
It is amazing that all the wonderful planes and pilots I have seen over the years have done so with all that awful FM equipment.
I will happily help out all you 2.4Ghz mavens and save the environment too. I will take away all that FM trash you have laying around waiting for the landfill. Heck I'll even buy that scrap at $2/lb.

dbcisco

From the FCC regulations:
Sec. 15.247
"Frequency hopping systems operating in the 2400-2483.5 MHz and 5725-5850 MHz bands shall use at least 75 hopping frequencies. The maximum 20 dB bandwidth of the hopping channel is 1 MHz. The average time of occupancy on any frequency shall not be greater than 0.4 seconds within a 30 second period."

2483.5 Mhz - 2400 Mhz = 83.5 Mhz spectrum

At 1 Mhz bandwidth allowed, this gives a maximum of 83 bands (channels) to use.

If you are getting more than 83 channels you are violating either the FCC regulations, the rules of mathematics, or the laws of physics.

blhollo2

My Feedback: (278)

if your going to go 2.4 go with the futaba..its bullet proof system but not rifle rated

Sessholvlaru

A buddy of mine had the same problem. Turned out to be the plug, as it was older and was really throwing out RF. Changed the plug to a newer one and the problem was gone.

JIMF14D

Well my 72mhz stuff slowly goes on Ebay and gets me money for more shiney new 2.4ghz Hitec stuff........ But am keeping my good old trusty Eclipse 7 as a back up now that is converted to 2.4GHZ with that nice $20 Hitec promotional module.


Now if the wind would just drop down we could fly!

bkdavy

My Feedback: (1)

I think there is a fundamental misunderstanding running through this thread. Just because the servos aren't twitching doesn't mean there isn't RF interference. In the PCM mode (72 MHZ or 2.4 ghz) you can still have RF interference, but the radios are better at masking the interference by frame rejection. If the RF environment deteriorates to the extent that its showing on 2.4, then its really bad. The only way to really determine if you've eliminated the RF interference is with a device to monitor frame rejection. 72 MHZ radios in the PPM mode will show you every RF glitch by twitching servos.

Brad

edwal07

In regards to your glitchs. Have you tried choke coils (RF Filters) on your servo leads? Horizon Hobbies sells the small ferrite rings that work wonders. They are recommended on Hanger 9's 1/4 scale Cub on the alieron servo leads. I would suggest you use them on your alierons first as you have 2 long antennas soaking up any interference around. Mount the rings as close to the receiver as possible and make at least 3 wraps thru the coil. If you have a servo close to the engine put one on it also. I have had glitches at times, mostly due to a loose plug cap or loose spark plug. I have DL and CRRC Pro Engines. For safety I use a small hose clamp at the base of the cap to make sure they stay tight. The spring ring around the cap does not keep a tight fit to the plug, the clamp insures good grounding. Do you have a metal to metal throttle linkage? There are lots of questions without looking at your setup. I am sure something is not properly grounded somewhere causing an arc, which is NOISE. Try the rings, they work for me.

dirtybird

My Feedback: (5)

A 2.4ghz channel is not like a frequency on 72mhz.
A large number of systems can operate on a 2.4ghz channel simultaneously without interfering with one another.

The following is a quote of the benefits of DSSM by Wikipedia.

Benefits

* Resistance to intended or unintended jamming
* Sharing of a single channel among multiple users
* Reduced signal/background-noise level hampers interception (stealth)
* Determination of relative timing between transmitter and receiver

dbcisco

Yup. Just like you can have the entire neighborhood using your wireless router. Not a particularly good idea.
Lets put it this way. 72Mhz gives a maximum dedicated throughput of 46 Mb/s of data and control signals. 2.4Ghz gives a maximum interlaced and shared throughput of 1200 Mb/s that has losses due to channel searching, changing, ID, encryption keys etc. Which comes down to this:

2.4 Ghz can transfer data a maximum of 20 times faster than 72Mhz. However, if 21 or more aircraft flying at the same time within over-lapping ranges then FM will transfer more data. FM throughput is constant, 2.4Ghz drops as the number of planes increases.

Joe Westrich

My Feedback: (95)

You need to be running a resister plug. It was mentioned twice in this thread so far. If you have not been running one, it will make a huge difference.

Loopman

My Feedback: (195)

I got my hands on a replacement plug and will try it in just a few minutes, it's an NGK BPM6F. As to the ferrite coils the distance I have to go for my servos to receiver is not all that great. I also twist all of my leads regardless of length. Like I stated earlier, right now with PCM I am not experiencing any interference but I would like to fly 2.4 so I do not have to lug around two transmitters. Trust me when I say, I have no loose wires or loose connections as I've done this for too long to fall into any short cuts that may produce RF. I truly believe that this little Homelite is the culprit but I'm hoping that the NGK plug will fix the issue.

Happy Flying!

Loopman

dbspl

I'm not sure I follow this. There are 83 available channels in the 2.4Ghz band. Are you saying the data rate is reduced on just one of those channels, or the entire 2.4Ghz band? It would seem to make more sense if it were just 1 channel, but that also would leave you another 82 channels that would be uneffected.

dbspl

dirtybird

My Feedback: (5)

I think he needs to provide more explanation of what he is writing about and where he gets his data

Nitro-Tom

[Spektrum offers in terms of functionality.

By they way if you read the testing that this guy has done, Spektrum DSM2 is not that great.


http://www.rcmodelreviews.com/2.4ghzshootout.shtml


[/quote]


Ok, first thing is first......I find it hard to believe a Futaba FASST system would not be "Glitching" if we put that in the same airframe we are all talking about here.....

Second, I do not think the research linked above is 100%....it has some flawed data......I.e. I do not see him testing Futaba FASST in the list of items tested. He says the DSM (JR/Spektrum) does not do "WELL" at low voltage......and I agree compared to some other systems available....the cutoff is high at just above 3V…BUT all the frequency hopping guys here with FASST and other 2.4 (Such as Hitec) cutoff at the same level…..so just run good packs and 6V and this is not an issue……brown outs will kill any computer radio setup.

http://www.youtube.com/watch_popup?v=PwnM9pBH9QM#t=233

Although the above video seems to be marked private, it showed the Spektrum and Futaba cutting off at the exact same low voltage……

I do think the frequency hopping is a good feature but I do not think it has been shown to be “Super Superior” to DSM2 and my radio is going to “Ignore” other signals on my channel without my GUID…..
I get new channels every time I boot (Every flight) and I never fly in an area with more than 5 guys in the air at once…

4 years with flying Spektrum and not one issue…..75-85% of the market at the last Joe Nall and only 1 or 2 “Incidents”……bring me 896 pilots at the same field with Futaba and we will see if it is any better….I suspect it would do fine as well…

All things considered here, I do not think either one is “Better” than the other……and I think most issues with either system are setup related…..

Texastbird

That isn't a resistor spark plug.

JIMF14D

Well to quote an old saying:One test is worth a 1000 opinions. I will modify it slightly and say 1 to 1000!