More than one receiver

Discuss the IOM class rules and interpretations

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Lester
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More than one receiver

Post by Lester » 26 Sep 2008, 08:47

D.2.4(a)(1)
Replace:
One receiver
With:
One or more receivers
The proposal from the Technical Sub-Committee to change the rule about the number of receivers, as above, may not quite do the complete job required.

Many owners (and those technically knowledgeable) think that the Spektrum AR7000 system and similar others comprises just one receiver. Other owners (and others equally technically knowledgeable) think that the AR7000 comprises two receivers. Both sides to the discussion are in complete agreement, I think, that whether there are one or two receivers, the system is designed to work as an integrated whole, and to offer the functions and functionality of a single receiving system.

An interesting experiment which may help to decide the question of the number of receivers in this system is to try to control a yacht when one or other of the receivers is removed or disabled. While we have not yet been able to disable the 'primary receiver' in a way which still allows the 'secondary' to pass its signal through for processing, we have been able to disconnect the secondary receiver and see that the system functions fine (under 'laboratory' conditions, anyway).

This makes it clear that the system comprises more than just 'one receiver'. But it may also make it clear that if the 'secondary' receiver cannot be used or cannot function as a stand-alone receiver, the system does not comprise two receivers either.

This observation gives a technical difficulty to the proposal to change the rules, because the change still does not, by itself, permit the Spektrum system (which, I believe, both sides to the discussion think is an excellent system and should be permitted in the class). The reason is the other concept of the class rules, that something not explicitly permitted is prohibited.

This is how the difficulty might unfold if the rule change was in place:

Code: Select all

Fred: Hi Lester, I see I am measuring your new IOM today.
Me:   Yup, and it sports the fancy Spektrum AR9000 receiver system.
Fred: So, Lester, how many receivers do you have there?
Me:   Well, I am told by some that there is but one receiver there.
Fred:  OK.  Let me remove this little black box with some sticky-out wires -- now, does your RC work?
Me:    Er, yes it does, but...
Fred:  Well, I can only certify your boat with this little box removed, since there is no explicit permission for it.
Me:    But the new rule says one or more receivers are permitted!
Fred:  Sure, but this is not a receiver, is it?  The RC functions fine without it, you told me there was just one receiver, and I can't see how this extra little box could work as the second receiver which is permitted by the rules...
What has happened is that the rule change deals with a count of 'things', while it really needs to deal with a count of 'functions'. My suggestion would be:
D.2.4(a)(1)
Replace:
One receiver
With:
One receiving system
Technical developments being what they are, it is interesting to read that the Spektrum DSM2 system actually broadcasts and receives (the same command sequence) on two separate frequencies, and the AR9000 really does have two receivers. What is important for the IOM, I believe, is that none of this matters while the 'intention' of the rule is respected -- the control of only two channels. Perhaps the entire rule about receivers can be removed...
Lester Gilbert
http://www.onemetre.net/

Andy Stevenson
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Post by Andy Stevenson » 26 Sep 2008, 14:11

Hi Lester,

That’s an interesting point, however I think the conversation might continue to a satisfactory conclusion:

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[...]Me: Ok, the receiver does work without the black box attached, but that doesn’t discount it from being a receiver. I’m lead to believe that it is, in fact, a second receiver that increases the performance of the first. It would seem foolish to design such a thing to only work with both connected; one is good, two is better. Either are allowed by the rules.
I worry a little about term sun as “receiving systemâ€
Andy Stevenson
"A little pain never hurt anyone!" Sam, aged 11

Lester
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Post by Lester » 27 Sep 2008, 17:40

andy111 wrote:I think the conversation might continue to a satisfactory conclusion:

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[...]Me: Ok, the receiver does work without the black box attached, but that doesn’t discount it from being a receiver. I’m lead to believe that it is, in fact, a second receiver that increases the performance of the first. It would seem foolish to design such a thing to only work with both connected; one is good, two is better. Either are allowed by the rules.
Hi Andy
I'm not entirely convinced (smile). Let me play Fred...

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Fred: We are agreed that the receiver works without the black box, no problem there.  The issue is, what then is this black box?  If it can't work by itself, it isn't a receiver as such.  We are also agreed that it improves the performance of the receiver, but such a performance-improving item is not what the rule permits.  The rule only permits another receiver (smile).
I worry a little about term sun as “receiving systemâ€
Lester Gilbert
http://www.onemetre.net/

RoyL
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Joined: 15 Dec 2003, 21:03

Post by RoyL » 27 Sep 2008, 18:12

Either the multi-box device is a single receiver or it is two or more receivers. Either way under the proposed rule change it would be legal. The concept of testing whether the two box device will function with one box disconnected is irrelevant. You can probably go to the circuit board of a receiver and remove a few parts and the device will still function (but not as well as designed), however that would not make the parts you removed from the circuit board illegal to have in an IOM.

Andy Stevenson
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Location: UK

Post by Andy Stevenson » 27 Sep 2008, 18:15

Hi Lester

I can see where Fred is coming from :) I would counter with something like:

Code: Select all

Me: Just because the black box doesn’t work on its own, doesn’t necessarily discount it from actually being a receiver. As I understand it the thing does receive signals from the transmitter, pretty much defining it as a receiver I would suggest. In fact Spektrum themselves call it a "remote receiver"[1]
[1]"The AR9000 combines two internal receivers and one remote receiver", http://www.spektrumrc.com/Products/Defa ... =SPMAR9000 accessed 27/09/08

Cheers
Andy Stevenson
"A little pain never hurt anyone!" Sam, aged 11

Barry Fox CAN262
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Post by Barry Fox CAN262 » 27 Sep 2008, 21:58

What happens if you say nothing about receivers at all. In order to have radio controlled sailing you need some method of transmitting control command to the boat and some method of receiving that control command and making it tell the servos what to do.

If you stop at defining that there can only be two controls on board anyway then to some extent the rest of it doesn't matter too much.

I just did a quick refresh of the rules and technically we aren't allowed transmitters (they aren't specifically mentioned) either so maybe the receivers aren't the issue.
Barry Fox
CAN 46
Vancouver Island, BC, Canada

Barry Fox CAN262
Posts: 354
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Sail number: CAN 46
Club: VMSS
Design: V8
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Post by Barry Fox CAN262 » 27 Sep 2008, 22:05

"Another class" says:

13. RADIO EQUIPMENT

13.1 No more than two servos are allowed; one shall be for sail control, the other for rudder control.

13.2 The method of fixing radio equipment, servos, receiver and batteries, to the hull, and or deck, are left to the skipper’s discretion.

13.3 The number and type of battery cells may be changed during a regatta provided that Class Rule 8.1 is not broken.

13.4 Servos, receivers and batteries shall not be movable during a heat, but may be moved between heats.

8.1 just says that the boat's minimum weight shall be XXX.

The first two rules, maybe the ones we might use, just define what you can control and not so much how you control them.

I'm not sure we need to care beyond that.
Barry Fox
CAN 46
Vancouver Island, BC, Canada

Andy Stevenson
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Post by Andy Stevenson » 27 Sep 2008, 23:36

Hi Barry

Good to hear from you.
What happens if you say nothing about receivers at all.
With closed class rules, as the IOM class rules are, not specifying receivers means you can't have one. Clearly not what we're aiming for.
technically we aren't allowed transmitters
Quite right, your boat would most certainly fail measurement if it sported a transmitter! :)
I'm not sure we need to care beyond that.
I think we do. The nature of closed class rules I'm afraid.

Cheers
Andy Stevenson
"A little pain never hurt anyone!" Sam, aged 11

Barry Fox CAN262
Posts: 354
Joined: 21 Apr 2007, 17:54
Sail number: CAN 46
Club: VMSS
Design: V8
Location: Vancouver Island, BC, Canada

Post by Barry Fox CAN262 » 28 Sep 2008, 05:16

Hi Andy,

I will admit I was just pushing it a bit about the transmitter.

But. . . if we are talking about radio controlled sailing, and we are, then there is a definite implication that we are allowing some form of communication between some kind of Tx in the skipper's hands and some kind of receiver in the boat that can translate the signal to move the two controls we do allow.

Further to Lester's informal test. Let's not get drawn into manufacturer hype. Forget what they call it and focus on what it does. From what I can see in Lester's description of his test it is apparent that the satellite receiver is not a receiver but is an antenna. All of the other DSS systems that we aren't even talking about utilize multiple antennas and we aren't upset about that. Equally they all have two receiving circuits built into that single case and we don't seem to have a problem accepting that they are already really dual receivers but we like to call them single receivers. Again packaging and marketing seems to have its hold on us and not function.

Luckily my primary boat still sails wonderfully on my Futaba PCM FM system, with one receiver. However it would be nice to have us resolve this so my secondary boat and its Futaba DSS radio are definitely legal.
Barry Fox
CAN 46
Vancouver Island, BC, Canada

Lester
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Post by Lester » 17 Feb 2009, 08:54

Is the Technical Sub-committee going to suggest a rule change to resolve this issue?
Lester Gilbert
http://www.onemetre.net/

Bruce Andersen
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Post by Bruce Andersen » 17 Feb 2009, 21:11

It was done by TSC, voted on at the last AGM, and passed. Now awaiting RSD (or its equivalent) to sign off on it. Sort of old news eh?

Lester
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Post by Lester » 18 Feb 2009, 12:15

Bruce Andersen wrote:Sort of old news eh?
Hi Bruce

Ya got me! I must have blinked and missed it... (smile)
Lester Gilbert
http://www.onemetre.net/

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