Radio equipment

kgrande · Post by **kgrande** » 08 Nov 2004, 19:34

I'm building a 1 metre, and I am now starting to think about radio gear. I don't know a lot about this, but I know that I wan't a Hitec digital arm winch.

1. Does the radio set itself make a difference? I have seen that some of the more expensive models have some fine tuning features, 2 yacht memory etc, and then there is the AM/FM difference. Is there any difference in the preciseness of the control?

2. Is it advisable to use a Hitec radio for the Hitec arm winch, or can equipment from different suppliers be mixed?

3. Can a standard servo be used for the rudder, or should I get something quicker and stronger?

4. Anything else I should think about?

All answers appreciated!

Best regards,

Kristoffer

awallin · Post by **awallin** » 08 Nov 2004, 21:35

kgrande wrote:I'm building a 1 metre, and I am now starting to think about radio gear. I don't know a lot about this, but I know that I wan't a Hitec digital arm winch.
1. Does the radio set itself make a difference? I have seen that some of the more expensive models have some fine tuning features, 2 yacht memory etc, and then there is the AM/FM difference. Is there any difference in the preciseness of the control?

In general PCM is better than FM and FM is better than AM when it comes to precision, repeatability, and interference resistance. In competitions you tend to see a lot of PCM sets, some FM sets and I believe Peter Stollery just came second at the Euros using the cheapest AM radio available... so go figure...

computer radio features I use (I have a Futaba T6X):
end point travel adjustment(ATV) is nice to have for fine tuning the in and out positions on the sheet and also limiting the rudder movement so no chafing or sticking of the rudder servo occurs.
exponential on both the sheet and the rudder give more precise control of the sheet when close hauled and more precise control of the rudder around the middle position.
on an IOM the sheet travel for all rigs can be made the same and I have not used the model memory on my radio.

2. Is it advisable to use a Hitec radio for the Hitec arm winch, or can equipment from different suppliers be mixed?

someone else could comment on the different type of connectors between receiver and servos. I believe there are still a few differing standards however at least Futaba and HiTec are the same.

3. Can a standard servo be used for the rudder, or should I get something quicker and stronger?

I have allways used the standard futaba S3003 or S148 servos. The speed and torque of the digital hitec servos is impressive though.

4. Anything else I should think about?

For some sets a short (20cm or so) antenna is available which is quite handy compared to the long ones.

take a look at http://www.spektrumrc.com/
It's a system that will(once it's available, currently they promise 2005 Q1) eliminate the need for crystals which I think is great. If I was buing a new radio I would get one that can be fitted with this module in the future.

KBits had an OK (bearing in mind it's a sales pitch) introduction to radios winches servos batteries and chargers in the catalog. maybe it's on the Kbits website ? If not, email me for a pdf scan.

Jamestj · Post by **Jamestj** » 10 Nov 2004, 00:33

Dual conversion receivers are also pretty impressive at rejecting noise but I would agree that outside, away from fluorescent tubes and other interference, anything goes.

Secretary · Post by **Secretary** » 10 Nov 2004, 15:54

awallin wrote:take a look at http://www.spektrumrc.com/
It's a system that will(once it's available, currently they promise 2005 Q1) eliminate the need for crystals which I think is great. If I was buing a new radio I would get one that can be fitted with this module in the future.

Anders,

I fired off an e-mail to Horizon people describing my (module-capable) setup (essentially, a Hitec Eclipse 7 with the original 72MHz module replaced by a 75MHz one from one of their pistol grip radios). The reply I got was short and concise:

The Spektrum modules will not work with 2-stick radios.

Don't know why this should be - or what the internal differences between 2-stick and pistol radios are (or if there are any). But at the very least - it appears that they don't want the headache of dealing with non-car applications...

Marko

mark · Post by **mark** » 11 Nov 2004, 08:32

Marko,
I was using a Sanwa Super EXZES in vancouver with a prototype Spektrumrc system, which is a two stick radio, with a third channel on a knob. It worked no problem.

I know the majority of these units have been sold to the car guys, i believe around 5000 of them, the majority is the pistol grip radios, which are not going to have a ton of channels

I'll be speaking to Paul this week so let me get the official lowdown, which you can then take back to Horizon.

The prototype JR module is being tested right now, hopefully ready for trials when sailing on Sunday

How's the little one...

Cheers,

Mark

Post by **Chairman** » 11 Nov 2004, 08:47

mark wrote:I'll be speaking to Paul this week so let me get the official lowdown, which you can then take back to Horizon.

Hi Mark

Could you keep the IOM Forum in the loop as well, please? I reckon we are all *extremely* interested in using the Spektrum system and dumping the crystal-swapping nightmare (smile). Most sailors I know in the UK who have a separate frequency module use the three-channel Futaba 3CV on 40 MHz.

Nigel · Post by **Nigel** » 11 Nov 2004, 11:05

Lester,

I got this from tha FAQ page of Spektrum RC:

Will this device work for the Futaba 3PJ?
The Futaba Module fits the 3PK and the 3PJ systems.

I think, but am not sure that the HF modul from the 3PJ pistol grip and the 3VC stick radio are the same. This would mean that the Spektrum modul should work for the 3VC.

Cheers

mark · Post by **mark** » 11 Nov 2004, 15:17

No problem Lester I'll keep you updated.

Nigel - Don't assume the module is the same across the pistol grip radios and the stick radios. I know on the JR radios it is not, there is a firmware change. sounds like we could do with Horizon publishing a table showing compatibility between modules & Tx's as they start shipping these.

One of the other benefits of using the system in Vancouver is the fact that it only uses a small antenna on the back of the TX module. Therefore when it rained, once i put the TX in the waterproof bag there is no large antenna sticking out providing a water channel into the TX.

Secondly, the receiver antenna I used was only about 4" long, was inside the boat & sat underneath my pot lid on the TS2.

Talk soon,

Mark

Nigel · Post by **Nigel** » 11 Nov 2004, 15:36

Mark,

no I know. For example the Kopropo pistol and stick modules are different. But for Futaba I think it'll work.

Cheers

Secretary · Post by **Secretary** » 11 Nov 2004, 18:33

mark wrote:Nigel - Don't assume the module is the same across the pistol grip radios and the stick radios. I know on the JR radios it is not, there is a firmware change. sounds like we could do with Horizon publishing a table showing compatibility between modules & Tx's as they start shipping these.

Hi Mark,

The Hitec ones are (although I am pretty sure you're right in that this may not be the case for ALL modules)...

I use Hitec Eclipse 7 - normally an airplane/heli radio when supplied with it's stock RF module. The module I have in there is the 75 MHz Spectra - originally intended for Hitec Aggressor SRX pistol-grip computer radio (but I'm pretty sure it's "Futaba-compatible"). It works no problem...

Maybe you can find out for me from Paul if the system would work in the above configuration?

Thanks...

Oh - and the little one - he's great. Couldn't ask for a better behaved baby (probably knows that, being third, we may give him away if he proves difficult). The other two have been more of a pain than a baby lately (needy!). Normal, I guess.

Good luck with Arnold's Cup... Kick some girlie-men's behinds...

Marko

Jamestj · Post by **Jamestj** » 14 Nov 2004, 20:50

Hi there,

I have seen a wireless network card which says that it works on 2.4 gHz which is the frequency used by the Spektrum transmitter module. I think that this is also used by Bluetooth devices as well. It could be a little crowded on 2.4 gHz. Does this mean that we have to turn off our hands free 'phones when near somebody who is using one of these modules?

awallin · Post by **awallin** » 14 Nov 2004, 22:05

Jamestj wrote:Hi there,
I have seen a wireless network card which says that it works on 2.4 gHz which is the frequency used by the Spektrum transmitter module. I think that this is also used by Bluetooth devices as well. It could be a little crowded on 2.4 gHz. Does this mean that we have to turn off our hands free 'phones when near somebody who is using one of these modules?

many, many people have wondered about the same things.

there is a long thread at rcniverse about the system where an employee from the manufacturer also answers questions:
http://www.rcuniverse.com/forum/Nomadio ... 790/tm.htm
(nomadio is a wheel-radio for cars that has the system built-in. the spektrumrc module is also made by nomadio if I understood things correctly)

for some more negative viewpoints see:
http://forums.radiocontrolzone.com/show ... p?t=181811

I think its best to wait until the product ships and people have tested it...

AW

Riku · Post by **Riku** » 04 Dec 2004, 10:26

Jamestj wrote: I think that this is also used by Bluetooth devices as well. It could be a little crowded on 2.4 gHz. Does this mean that we have to turn off our hands free 'phones when near somebody who is using one of these modules?
:?

Well, it depends on the number of Nomadio and Bluetooth hands free users. If there are few (less than 30..50 totally, maybe some more?) Nomadio systems and Bluetooth devices active in the same area, all of them will work very well experiencing negligible interference.

I am quite confident that Nomadio system will perform at least as well as the best PCM systems today. However, the Nomadio is a duplex system (transmitting in both directions), which is not allowed by IOM rules if I remember correctly?!

awallin · Post by **awallin** » 04 Dec 2004, 10:37

Riku wrote: I am quite confident that Nomadio system will perform at least as well as the best PCM systems today. However, the Nomadio is a duplex system (transmitting in both directions), which is not allowed by IOM rules if I remember correctly?!

Hi Riku !

Yes IOM class rule C.5.3 (c) reads:

(c) Except for control unit positioning information, no radio transmissions from the boat shall be made.

I actually asked SpektrumRC abou this on their FAQ page:
http://www.spektrumrc.com/DSM/FAQs/Default.aspx

Q:Will the standard receiver (without optional telemetry parts) transmit anything back to the transmitter? I am asking because the rules for the class I compete in specifically prohibit this.
A: The receiver is actually a transceiver and does transmit a signal, but without the telemetry module no meaningful information is being transmitted.

but a change to the IOM class rule would still maybe be needed...

Jamestj · Post by **Jamestj** » 04 Dec 2004, 19:46

An aquaintance recently set up a wireless network for a pc and had been impressed with the range. It does not seem to be upset by other devices working at the same frequency and it does not seem to upset other equipment, either. I understand that similar technology is used in the Spectrum and Nomadio systems. If the IOM rules change, I would use it since I am starting from scratch. How does one approach "The Powers that Be" to see if the rules could be modified?

Come to think of it, the position of the transmission within the radio spectrum is controled by the signal from the receiver - therefore isn't the return signal from the receiver "control unit positioning information" ?

awallin · Post by **awallin** » 04 Dec 2004, 20:22

Jamestj wrote: If the IOM rules change, I would use it since I am starting from scratch. How does one approach "The Powers that Be" to see if the rules could be modified?

see
http://www.iomclass.org/technical.htm

If this system becomes(spektrumrc release dates are jan-mar2005) popular it is likely/possible that the Techincal Sub Committee will request an interpretation or a rule change.

ptercinet · Post by **ptercinet** » 05 Dec 2004, 08:58

hi everybody,

I note on http://www.spektrumrc.com/ :

DSM System Specifications
Frequency Band
2.400-2.4835 GHz
Channels
79
Channel Spacing
1 MHz

For information Bluetooth specification is :
2.4 to 2.4835 Ghz Technologie FHSS (Frequency hoping spread spectrum)
79 channels spacing 1Mhz
1600 Hop /S GFSK modulation

very similar !!!

in France ART(telecom administration regulation) law is : 10 mw for outdor operation in 2454-2483 band. quite low !!!

and 100mw for 2400-2454 Mhz

I'dont find DSM power specification, so I'm not sure DSM is legal for outdoor operation in every countries.

Pierre

Riku · Post by **Riku** » 05 Dec 2004, 15:12

ptercinet wrote:hi everybody,

I note on http://www.spektrumrc.com/ :

DSM System Specifications
Frequency Band
2.400-2.4835 GHz
Channels
79
Channel Spacing
1 MHz

For information Bluetooth specification is :
2.4 to 2.4835 Ghz Technologie FHSS (Frequency hoping spread spectrum)
79 channels spacing 1Mhz
1600 Hop /S GFSK modulation

very similar !!!

in France ART(telecom administration regulation) law is : 10 mw for outdor operation in 2454-2483 band. quite low !!!

and 100mw for 2400-2454 Mhz

I'dont find DSM power specification, so I'm not sure DSM is legal for outdoor operation in every countries.

Pierre

Ok, the difference between DSM and Bluetooth is that DSM is a real spread spectrum system since it occupies signal spreading with a pseudo-random spreading sequence. Bluetooth occupies regular radio signalling (FSK modulation) with frequency hopping, which makes it "spread spectrum". (By the way, maximum output power of most Bluetooth devices is 1mW)

The power specification (on ISM band) is such that 100mW is the maximum allowed transmit power. I would assume that DSM is designed to fullfill these specifications, so the maximum output power is 100mW! France is an exception here, so I guess that DSM is not allowed there if the software cannot be configured to use only allowed channels (0-52??).

ptercinet · Post by **ptercinet** » 06 Dec 2004, 11:29

Hi Riku,

please could you clarify "that DSM is a real spread spectrum system since it occupies signal spreading with a pseudo-random spreading sequence"

DSM is a Spreadspectrum (like CDMA) over the ISM Band, or over each sub channel (1Mhz) in this last case DSM could be understande as Ã mix beetween CDMA/FDMA.

Regards

Riku · Post by **Riku** » 06 Dec 2004, 12:47

ptercinet wrote:Hi Riku,

please could you clarify "that DSM is a real spread spectrum system since it occupies signal spreading with a pseudo-random spreading sequence"

DSM is a Spreadspectrum (like CDMA) over the ISM Band, or over each sub channel (1Mhz) in this last case DSM could be understande as Ã mix beetween CDMA/FDMA.

Regards

Yes, DSM is spread spectrum over each sub channel (1 MHz), so you could say it is a mix of CDMA and FDMA. I don't know if you can operate two (or more) DSM devices on the same channel. If not*, the system is actually FDMA and the spread spectrum signalling is used only to quarantee better detectability in noisy environment (meaning that lower transmitter output power can be used)...

*Actually, the operation of multiple DSM devices on the same channel would require complex power controlling by some "base station" (as in UMTS) and that is why user separation is probably based "only" on FDMA (not CDMA!) in DSM! However, the spread spectrum signalling offers significant advantages over traditional signalling, and that is why it is used in DSM...

ptercinet · Post by **ptercinet** » 07 Dec 2004, 10:27

Hi Riku,

Where find more information on DSM system, is it comply whith
EN 300 328 ETSI regulation ?

from my point of view ISM band is a licence free band, but you need to
be inline with regulation.

it is very difficult to find information on ISM band, but on
documents I found a distinction between short range device (telecommand,telecontrol,alarm etc....) and LAN RLAN.

focussing on 2.4Ghz band :
SRDevice max power 10mw
RLAN 100mw

Have you some informations ?

Rob Davis · Post by **Rob Davis** » 07 Dec 2004, 14:32

Some interesting discussions. It doesn't seem like anyone has contacted Paul Beard regarding these questions. If you want real answers you might consider doing so.

Paul's website is www.modelavionics.com

Regarding todays equipment, you mean to tell me that there's no detectable RF coming from the radio/receiver/servo/batteries we use? As I understand Paul's system (which I've seen) is that the receiver does bind to the transmitter but only for pairing. There's a button on the receiver that enables it to do so. So while sailing there's no way to push the button and pair.

Jamestj · Post by **Jamestj** » 07 Dec 2004, 14:41

Modelavionics seems to have been hi-jacked my Magiclamps

Jamestj · Post by **Jamestj** » 07 Dec 2004, 15:03

Modelavionics is back - probably being updated. Where do I click, Rob?

I read about a receiver which locked on to the transmitter when you pressed a button in a model car magazine a few weeks ago but I understood that was 40mHz. (the button was on the receiver, not in the magazine

)

Rob Davis · Post by **Rob Davis** » 09 Dec 2004, 04:37

Jamestj wrote:Modelavionics is back - probably being updated. Where do I click, Rob?

In the left hand upper corner there's a contact link. That will goto Paul.

Rob

awallin · Post by **awallin** » 29 Dec 2004, 10:09

Rob Davis wrote:
Jamestj wrote:Modelavionics is back - probably being updated. Where do I click, Rob?
In the left hand upper corner there's a contact link. That will goto Paul.
Rob

I've sent a few emails to both spektrumrc and modelavionics.

Spektrumrc says that the first set of modules to be releasec jan-feb 2005 will not work on any stick radio(like the Optic 6 or similar) and they do not have an ETA for a module that will.

Modelavionics says that the upcoming modules will work with the Sanwa Exzes stick radio.
I tried to google for the exzes but only found a few links, could it be an older model not being produced anymore ?

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