What's the frequency?..... Kenneth? (sorry)

r011ingthunder

Anyone know the legal range for transmitters in Ireland? I know US transmitters are not legal here, but it'd be nice to know exactly what is compliant.
Thanks.

vectra

27Mhz and 40Mhz as far as I know.

also
2.4Ghz


Coolwings will verify this or correct me if i am wrong.
He is more experienced than me at that sort of thing. :cool:

r011ingthunder

vectra wrote:

27Mhz and 40Mhz as far as I know.

also
2.4Ghz


Coolwings will verify this or correct me if i am wrong.
He is more experienced than me at that sort of thing. :cool:

OK, so excuse my ignorance but what does the "65" mean on my transmitter crystal then, and how can I tell when buying a transmitter what frequency it broadcasts at?
Btw, thanks vectra.

vectra

65 is the channel it is on.
Which is 75Mhz which in turn is Illegal here.
again. I am not certain. maybe 75 is used for flight?

Maybe this will help
Frequency Channel
26.995 Brown
27.045 Red
27.095 Orange
27.145 Yellow
27.195 Green
75.410 61
75.430 62
75.450 63
75.470 64
75.490 65
75.510 66
75.530 67
75.550 68
75.570 69
75.590 70
75.610 71
75.630 72
75.650 73
75.670 74
75.690 75
75.710 76
75.730 77
75.750 78
75.770 79
75.790 80
75.810 81
75.830 82
75.850 83
75.870 84
75.890 85
75.910 86
75.930 87
75.950 88
75.970 89
75.990 90

r011ingthunder

Hmm, must be a mistake somewhere:
1. I misread the crystal (I don't think I did)
2. GH&M sold me a dodgy transmitter (Not a chance in hell)
3. Legal frequencies are different for ground & air (most probably)
But thanks again vectra!

vectra

r011ingthunder wrote:

Hmm, must be a mistake somewhere:
1. I misread the crystal (I don't think I did)
2. GH&M sold me a dodgy transmitter (Not a chance in hell)
3. Legal frequencies are different for ground & air (most probably)
But thanks again vectra!

Most likely number one
Not a hope number 2
3 .. Possibly

Like I said
Coolwings where are you ....

The Doktor

27Mhz + 40Mhz for ground
35Mhz for flight.
Unless ye got a licence for somthin else...
http://www.comreg.ie/publications/revisd_radio_frequency_plan_-_national_table_of_frequency_allocations_for_ireland.583.102661.p.html

Have a look if ye need to, just search for "model" and you will see whats allowed

mugenextreme

Just reading throught that document , i am amazed at how few crystals are there . By the looks of it on 27mhz you can only run standard colours no splits, on 40mhz you are only allowed 4 different cyrstals 40.665mhz 40.675, 40.685, 40.695. That is a very narrow band of legal crystals on the 40mhz range, i know guys are using crystals all the way up to 40.925mhz. Out of interest how would this effect a club if there members used any crystals outside the range. I know we talked before about getting the spektrum for flight craft check, can any one remember who we need to contact or do they have a contact??

vectra

I dont understand how these thing work at all
In our club some guys use 40Mhz AM and others use 40Mhz FM.. Still they get interferance from each other..

coolwings

I reckon that Ro11ingThunder is using channel 65 on the 35FM band.
That would be flying frequency (35) frequency modulation(FM) channel 65 (35.050) and signal type is usually PPM (as opposed to PCM).

The separation between channels is usually 10 khz, or 0.010 megahertz.
So eg 35.010, 35.020, 35.030 are all separate channels of 35FM.

Of course the transmitter battery has to be properly charged so as to allow full volume transmission, or another guy on an adjacent channel may "shout you down" causing glitches.

On very rare occasions I have seen a transmitter exactly 10 channels away affect another.
A damaged crystal can do the same, but is more common, and affects the adjacent channels with RF (radio frequency) splatter interference. Usually the damaged xtal will crossover the channels of the user's radio eg throttle and aileron get mixed up affecting each other and that is a giveaway to the cause.
Older transmitters do splatter a lot, probably their tuning accuracy wanders over time.
For those reasons I like to change/upgrade my tx about every 4 years.

vectra

coolwings wrote:

Of course the transmitter battery has to be properly charged so as to allow full volume transmission, or another guy on an adjacent channel may "shout you down" causing glitches.

.

Now thats a valid point I hadnt thought of.

I knew you would come up with something. :cool:

r011ingthunder

coolwings wrote:

I reckon that Ro11ingThunder is using channel 65 on the 35FM band.
That would be flying frequency (35) frequency modulation(FM) channel 65 (35.050) and signal type is usually PPM (as opposed to PCM).

Thanks for the clarification coolwings, but what's the difference between PPM and PCM?

coolwings

Vectra: It's a bit like in a concert ... the band is very loud, but you can still hear what the person beside you is saying because your brain listens to "their" voice's frequency, and filters out as much of the music as possible.
But if they speak softly, the sheer volume shouts them down, irrespective of frequency difference, and no matter how well the filters work.

eg In my own experience 35FM works well enough (plane out to 600 yards range each side) within one mile of the RTE Kippure VHF mast, and (in other locations) near to mobile phone masts (mast 200 yards away), and they must must be blasting out (if only we could hear it). So I'm perfectly happy on 35FM. I wonder how well 2.4 gigs will fare in similar situations, seeing as it is an awful lot nearer to the ultra high frequencies these systems use. Time will tell.


Ro11ingthunder: PPM is the "normal" mode of transmission to a model. It is the data packet specification.
There is PPM 17 and PPM 18.
PPM accounts for over 90% of all radio control, and works across the various makes.

PCM is different, and non-compatible across different makes.
PCM allows a special receiver to be used which has pre-programmed fail safes, like cutting throttle to zero, if transmission is lost. It has mostly been used by people with interference filled metal built models ... eg glowfuel helis, for better reception ... or by club modellers where an industrial radio interference source is nearby ... eg factory or military base.

I use the best 35FM I can afford, I can select PPM17 or PPM18 from my JR MC22 radio and talk to every make of receiver I have tried to date.
So I never felt any need myself to "upgrade" and pay extra for fancy PCM receivers, but it depends a lot on where you live.

Competition heli fliers would be the biggest group using PCM gear, because of their special needs.

vectra

coolwings wrote:

Vectra: It's a bit like in a concert ... the band is very loud, but you can still hear what the person beside you is saying because your brain listens to "their" voice's frequency, and filters out as much of tha music as possible.
But if they speak softly, the sheer volume shouts them down, irrespective of frequency difference, and no matter how well the filters work.

Good description.
cheers

syl77

I wonder how well 2.4 gigs will fare in similar situations, seeing as it is an awful lot nearer to the ultra high frequencies these systems use. Time will tell.

The main worry for 2.4ghz is noise interference. Some video transmitters for aerial photography transmit at 2.4ghz which at certain ranges can cause interference via noise.
The spectrum radio binds to the Rx by selecting a free channel and then only using that channel to communicate. It then uses that channel and a GUID to send its data which is always sent twice. If one packet it dropped, it receives the second directly after. I talked to Paul Beard who developed the spectrum radio and its protocol and he mentioned that new spectrum Rx's will come with a data screen which will tell how many packets were lost with in a session.

coolwings

A lot remains to be proven.
Graupner did tests at 2000 to 2600 metres, a long distance any way you look at it, and 100% results. The models were flown by the pilot 2miles away by giving directions over mobile phones via spotters. That is very impressive. (Of course 35FM would have functioned over 1500 metres, and we regularly test 35FM to over a mile with no "wow look how amazingly good it is" comments. )

My thoughts about 2.4 ghz are that in a city where thousands or nearby houses may contain a wireless modem/router, on 2.4 gigs, and industrial users (eg mercedes garages use 2.4 gigs to update software in their cars as they drive through the area) the number of occupied channels could be extreme.
Now those modes of use will not have the safety protocols that RC radios contain, but they will still be on the same waveband.
My own research suggests that high power users of 2.4 gigs may use one selected channel with full power, but still bleed, splatter and pollute 10adjacent channels so as to make them unusable.
In these particular (a high population nearby) circumstances there could be easily 500 users of 2.4 gigs approx 1 mile of an RC model user, occupying very many 2.4 ghz channels.
So the spec sounds good, the tests look good, but the real world is a different place, eh? :-)
Time will tell on 2.4 ghz.
So I suppose it's looking good, but so far only better in some ways.

Meanwhile don't forget 35FM is tested, proven, cheap, reliable, passes through most solid objects between the user and his model, and has a legally reserved waveband. It just doesn't have so many channels, but if nobody but other fliers uses it ... how many do you need?

One advantage ... the 2.4 gigs system from JR (not the Spektrum or Futaba systems at present) can do telemetry from model back to pilot. Airspeed sensors, rpm, temperature, lots of "dashboard info", will now be displayed on the radio, if the right gear has been purchased.

vectra

coolwings wrote:

One advantage ... the 2.4 gigs system from JR (not the Spektrum or Futaba systems at present) can do telemetry from model back to pilot. Airspeed sensors, rpm, temperature, lots of "dashboard info", will now be displayed on the radio, if the right gear has been purchased.

You mean this doesnt work ??
Spektrum Telemetry System

syl77

As far as I know, spectrum and JR have joined up to bring out new 2.4gHz radios. The new spectrum 9Ch radio out is in fact the JR 9303 (or 9X) which has a few software updates and of course the spectrum module inside. Been waiting for this for some time now....:)

coolwings

Vectra: That was fast, eh? It used to be you would wait a year for a new product to come out, now they seem to get them into production in only a month or two!

syl77 wrote:

As far as I know, spectrum and JR have joined up to bring out new 2.4gHz radios. The new spectrum 9Ch radio out is in fact the JR 9303 (or 9X) which has a few software updates and of course the spectrum module inside. Been waiting for this for some time now....:)

Dunno about 9303, but the synthesizer 35FM module for my 10-12 channel European JR MC-22S is removable, and I could take it out and plug in a 2.4gig module in under 20 seconds ..... if I wanted to.
Absolutely no need to buy a new radio transmitter, if you chose right when buying the last time .. swop the module, and that's it, done!

The modules are shipping to GreenHobbyModel this week. They seem to fit everything over 8 channels, JR (MX-22, MX-24, MC-19, MC-22, MC-24), versions that work in Futaba & MPX too.

I won't be putting any of my money out for this new stuff right now, what I already have works perfectly. I rather like being able to use all the (totally reliable) 35FM receivers I have accumulated, and 2.4 gigs will not talk to them, only talks to/with other 2.4gig receivers. Don't really fancy shelling out for a dozen new but unnecessary receivers!

Will keep an eye on how other "early birds" get on with it though.

vectra

coolwings wrote:

Vectra: That was fast, eh? It used to be you would wait a year for a new product to come out, now they seem to get them into production in only a month or two!

A bit like building a new PC these days.. Build a high spec today and it is Outdated next week.. :mad:

syl77

The Spectrum 9Ch will be the same as the 9303 but will not have a removal module at the back. They are however spectrum modules out there for already existing futaba and JR radios, but these were developed with out input from the radio manufactuers. The 9303 9ch from spectrum is the first radio where by JR and spectrum sat down and talked about it.

Will keep an eye on how other "early birds" get on with it though.

The 7ch and 6ch spectrum have been out there for some time now with little problems... I think I will make the change over this winter, I like the benefits to much.

coolwings

syl77 wrote:

...The 7ch and 6ch spectrum have been out there for some time now with little problems...

Problems ... or just a slippy way of interpreting the advantages and sliding over disadvantages.....

You have to read between the lines to decide ...

When Spectrum 6 came out - they said - get one now - it does it all, it's the bees knees, etc, etc, etc.
Then Spectrum 7 comes out, and now they say say Spectrum 6 is mainly for parkfly and indoors, but Spectrum 7 get one now - Spectrum 7 does it all, it's the bees knees, etc, etc, etc

Yeah right.
Like I haven't read those kind of claims before about nimh batteries, lipoly batteries, handheld GPS, windows vista, and a gazillion other "new technology" items just hot off the designers table, and initial production line.

But my planes are not disposable beta testers for some radio company ... not when the previous technology works absolutely perfectly, and it will cost extra to change.

I looked at the Spectrum menus - they remind me of a "first computer radio" range of options. And the trim switches are plasticky. I'm a bit beyond that and am used to nicer stuff. So I want every kind of mixer, flight phases, and obscure options like (for example) swopping the channel output functions in a receiver. I get them in a MC-22S which also has push button synthesized channel switching in the 35 FM waveband.

I can wait for 2.4 gigs to get plenty better.
Lots of telemetry modules are about to be invented and appear in the next year or two.
Then they will want video, and will notice that 2.4 gigs is too slow for colour. Stuff will appear on 4.5 gigs or higher, and at that point it really starts to get interesting.
So there is no hurry on me. I will check out the 10 channel versions carefully soon, but won't buy one for at least another generation of improvements in this technology.
I will be most interested to see how you get on with yours. Pls keep us posted.

syl77

Problems ... or just a slippy way of interpreting the advantages and sliding over disadvantages.....

I suppose it’s the way you interpret it. When I spoke to Paul, he went over a few issues (mainly with receivers) and what was done to correct this. He can be seen commenting on some of these issues on other forums. Not many radio manufacturers do this.

When Spectrum 6 came out - they said - get one now - it does it all, it's the bees knees, etc, etc, etc.
Then Spectrum 7 comes out, and now they say say Spectrum 6 is mainly for parkfly and indoors, but Spectrum 7 get one now - Spectrum 7 does it all, it's the bees knees, etc, etc, etc

That’s advertising… people aren't fooled, as far as I know the 6ch didn’t sell well, everyone waited for the 7ch.

But my planes are not disposable beta testers for some radio company ... not when the previous technology works absolutely perfectly, and it will cost extra to change.

And neither are mine, thats one reason why manafacturers have team pilots.

If the previous technology works great for someone - great stick with it, no point fixing something that’s broken. But if newer technology starts to look more appealing (in my case the 9303 and not the 7ch - I didn’t and still don’t like the feel of it and its menus) with benefits such as faster transmission, no crystal, no lockouts, no waiting around, then I think its time to move.
From talking to RC pilots and reading forums, people who have gone the spectrum route have never looked back. Its transmission and servo speed has become the main reason the new "crack" move has been introduced with 3D heli.
There will always be a newer more better product in the pipe line, you just got to pick your time to upgrade and go with it.