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Re: wireless serial Radio-Link

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In general, much less than the price of a live person with an injury.

George
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Re: wireless serial Radio-Link
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Exactly,

Militarily speaking, a dead person is a -1, an
injured person is a -3 (the injured and 2 to
take care of him).   At least that's what they
told me in basic training.






Re: wireless serial Radio-Link
On 6 Jul, in article

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There has been at least one court case after inquest in the UK of
model aircraft losing control and killing a small boy.

There is a web page about it on the Radio Control Modelling group site.

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They should always check what they are doing for safety and risk assessment
many don't.

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Re: wireless serial Radio-Link
On Tue, 6 Jul 2004 23:05:02 +0000 (UTC), paul$@pcserv.demon.co.uk (Paul

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If you are referring to the accident in April 2003 on Dartford Heath in Kent
then the model was unsafe to fly in the first place and it had nothing to do
with the quality of the radio equipment. It was the structural airframe that
failed.

And it was a girl.

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Re: wireless serial Radio-Link
On Wednesday, in article

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No there was an earlier ibncident, as I read it originally around
2001/2002, after it had concluded. That case was control failure as they
specifically stated it should have had a failsafe on it.

The reason I know it was before 2003 is because a particular hardware design
was finished long before April 2003, for which I was doing research at the
time.

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In that particular incident I do remember it being a boy.

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Look for Joint Radio Control Users Committee, that is where I am sure I
originally found the details. The site has changed a lot since 2001

        <http://www.ukrcc.org/

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Re: wireless serial Radio-Link

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If you really need full-duplex you need two separate radio systems
working on two separate frequency bands. In which countries should
this system be usable (frequency allocation) ?

If you insist of using a single frequency band,be prepared to use
duplex filters, which are big, heavy and expensive.

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What data rate do you need ?
What reliability do you need, 90 %,99 %, 99.9 etc of the time ?
Do you always have a line of sight path to the mobile unit ?

Depending of these factors you may end up in a power consumption of
several watts.

Paul


Re: wireless serial Radio-Link
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It'll run it in Europe (UK and Germany). The full-duplex is basically
desired to ease the protocol as collisions can't occur if both ends
want to send at the same time. I use the radio-link to control a model
helicopter and would like to have real time behaviour.

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That is not acceptable in my relatively small helicopter.

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The data rate is not crucial. As little as 4.8kb/s or even 1.2kbaud
would do.

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the higher the better :) As a 100% are impossible anyways the protocol
needs to handle lost packages. A reliability of above 90% seems ok to
me.

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The heli will be operated obviously outside but a tree inbetween
shouldn't be a problem.

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Thanks a lot.

Re: wireless serial Radio-Link
On 5 Jul, in article

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Well if you are using it to control and feedback from a model helicopter
then in UK you can ONLY use these bands, as this is classed as a Short
Range Radio Device

 To control the model

        40MHz  AM/FM (NOT allowed for airbourne models)

        70MHz  FM  (ONLY for airbourne models)

        459MHz FM  (for any model)

  For feedback (telemetry) from the model

        433MHz FM

There are restrictions on transmitter power, see IR2030 document on
www.radio.gov.uk . Each band only allows a channel width of 10KHz.

Using other bands and other power levels will not go done well, with
many people and could land you in some cases with large fines and/or prison.

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There are several lightweight modules available to do this even at low data
datas 4.8KB and below without extra modem chips. It is possible to make a
simple board with lightweight and battery powered transmitters and receivers.
I have done it for a completely different project using 459MHz and 433MHz.

See CDP series (www.lprs.co.uk) and ST500 series (www.woodanddouglas.co.uk)
for their specs.

Both have either switch selectable or programmeable channel selection, see
examples on www.gnuh8.org.uk, where I have put up an example of how
to control the woodanddouglas ST500 series module from an H8 which has
3 UARTS. You need to change the channel selection to avoid clashes with
other users. You will also need to look at fitting a failsafe to the
model for loss of communications.

See www.snugglebot.org.uk for some information and photo of controllers
with 2 off 2 axis joysticks, channel selection, multiple buttons and LEDs
even for feedback of remote end battery levels.

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Using these modules on two bands will be an example of the easiest methods,
to get higher reliability. Both units are metal cased.

Put a Radio Ham transmitter next to the 433MHz receiver and the 433Mhz only
got about 2% distortion on a sinewave transmission when the tip of the
459MHz was less than 2cm from the PCB on the underside of the receiver!

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That would depend on the tree, time of year, and of course whether it has
been raining......

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These sorts of modules have evry low power consumption, because they are
meant for Short Range Radio Devices that have limited range and limited
battery power.

Your model helicopter is probably using 70MHz already, so your simplest
solution is add a 433MHz telemetry channel to the model.
 
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