wireless serial Radio-Link

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Hi,

I'm looking for a wireles serial radio-link that runs Full-Duplex.
Does any one know about one out there?
It's for a mobile application, hence size and power consumption should
be ideally as little as possible while coping with distances of at
least up to 400 metres.

thnanks.
stefan

Re: wireless serial Radio-Link
I used Aerocomm modules. Though it was not mobil application. But I found it
easy to use and convenient.
Aleks.
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Re: wireless serial Radio-Link

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What Aerocomm modules did you use?  And what kind of
throughput and latency were you getting?


Re: wireless serial Radio-Link
I used AC4490 -200 on 9600 Baud. It is installed inside the box on a pole.
The device counts KYZ energy meter pulses and sends replies on modbus-like
packets once in 5 minutes. The length of a packet is about 32 bytes.

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found it



Re: wireless serial Radio-Link

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What is the datarate that you will need?
 If you want really Full-Duplex on the air you will need two independent
radiolinks (in case of a high troughput you may need this anyway)

If your datarate requirement is low enough a duplex link that emulate
full-duplex as seen from either  should be OK?


HTH

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Morten
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Re: wireless serial Radio-Link

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The datarate is not critical. As little as 1.2kbaud would be ok.

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Having an emulated full-duplex makes the protocol more difficult and I
ideally would like to have some real-time behaviour.

Thanks,
Stefan

Re: wireless serial Radio-Link
news@stefan-strobl.de (Stefan) wrote in message
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The ATMEL ATR2406 seems to be close to what you need, except for the
range of 400 meters.  You can add an external RF amp & transceivers.

--- Quote from ATMEL ---

The IC is manufactured using Atmel's innovative SiGe BiCMOS technology
and packaged in an ultra-compact QFN32 plastic package (5 x 5 mm). The
low-IF receiver architecture enables low external Bill of Material
(BOM) costs, while offering a superior RF performance. The high
receiver sensitivity of -93 dBm and high output power of up to 4 dBm
enables link ranges of up to 70 meters. The transceiver supports data
rates of 72, 144, 288, 576 and 1.152 kbit/s and offers receiver signal
strength indication (RSSI) as well as a digital clock recovery.

The ATR2406 interfaces seamlessly with Atmel's AVR Flash
microcontrollers and allows for the design of a complete chipset
solution for ISM applications. While being operated alongside the AVR
microcontroller, the average current consumption in typical low-data
rate applications is less than 5 mA when operated in burst-mode. This
complete solution offers the best combination of low cost and low
current consumption while leaving designers maximum flexibility.
Atmel's Marketing Director for Communications products, Uwe
Barthelmes, stated, "Using the ATR2406 RF reference design and
complete AVR software drivers available from Atmel, interfacing to the
AVR is as easy as sending data to a UART."

Samples of the ATR2406 in ultra-compact QFN32 plastic packages (5 x 5
mm) are available now, pricing starts at US$ 1.80 (100 k). High-volume
production will start August 2004. A complete evaluation kit including
reference designs and RF protocol firmware to simplify the design are
available. The development kit ATR2406-DEV-KIT is priced at US$ 500
and can be ordered via Atmel's local sales offices.


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Re: wireless serial Radio-Link
Take a look at this little nifty device:
http://www.nordicsemi.no/index.cfm?obj=product&act=display&pro82 %

I should contain everything you will need for your telemetry/control of the
helicopter. (The 433MHz band in Europe is fairly open - but you will need to
check with the appropriate rules regarding control of toys)

The respons you are looking for, as in real time control of a RC Helicopter,
will not be detrimented by a turnaroundtime  less than 10ms. I believe that
low weight is more important that a couple of extra bytes in the protocol?

The range you want is  in the best conditions possible, you have practically
line-of-sight and a proper choice of antenna should give you the link budget
you want.

HTH

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Morten
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Re: wireless serial Radio-Link
On Tue, 6 Jul 2004 08:31:06 +0200, "Raider of the Lost Electron"

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IMHO, anybody trying to use a shared frequency band for _control_ of a
model aircraft or other flying device should be put behind bars to
think what he/she is doing !!

If other legal signals on that frequency band disrupts the control
link for say, a few minutes, it is quite likely that the aircraft goes
out of control and may hit someone in the head with disastrous
consequences.

For instance, if some LPD (10-100 mW) is used for a control link on
the 433 MHz band which is also used by radio amateurs, it is quite
likely, that the control link may be interrupted by amateur radio
transmissions, especially since the 433 MHz range is used for the
mobile to repeater transmissions in many countries. A mobile amateur
radio transmitter, which are typically 30-50 W or about 30 dB more
than the LPD, may block the control link when moving in the
neighbourhood.

Use proper frequency bands specially allocated for model control to
control the helicopter.

Using some other band for telemetry will also solve the duplex
problem. If a shared frequency band is used, the downlink could suffer
interference from other legal users of the band, so this must be
considered, when designing the system.

Paul
  

Re: wireless serial Radio-Link

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[...]

As the OP wants to fly his model in the UK, it would be worth mentioning
that Ofcom, the UK regulating body, has a dedicated band around 35 MHz for
flying gadgets.  433 MHz can be used to transmit data *from* the model.  
Some more details can be foud here:

http://www.ofcom.org.uk/static/archive/ra/publication/ra_info/ra60.htm


HTH,
   Vadim

Re: wireless serial Radio-Link

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                                                                 ^^^^^^
Flying Gadgets MUST use 70MHz band, 40MHz is for land/water toys.
 
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--
Paul Carpenter        | snipped-for-privacy@pcserv.demon.co.uk
<http://www.pcserv.demon.co.uk/ Main Site
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Re: wireless serial Radio-Link
On Tue, 6 Jul 2004 23:04:59 +0000 (UTC), Paul Carpenter

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Any link?  The document I've pointed to (RA60) says "The 35 MHz is
dedicated solely to aeronautical modelling."  I couldn't find IR2030
document on the Ofcom site.

I am also curious because my son is tempting me to buy a helicopter.  The
last time I asked in the model shop the bands were 40 MHz for surface, 35
for air and 27 for any model.

   Vadim

Re: wireless serial Radio-Link

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Damn should not post late at night like now, after checking documents
and putting wrong thing. You are right about 35MHz and not as I WRONGLY put
70MHz. Don't know what I was thinking there, so I am double checking my
points and have multiple documents open at the same time to be sure this time!

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IR2030 is the more detailed document by band usage titled

                UK Radio Interface Requirement 2030
                        Short Range Devices

My copy is dated as a PDF from 5th January 2001, originally from
www.radio.gov.uk (Radio Communications Agency) before the recent amalgamation
of the various agencies under OfCom. This is for various bands not just
models and includes all sorts of telemetry band details.

Ofcom website details about all Short range device bands (helps for sorting
out what might also be using part of same band or close by) is referenced
in RA114:-

  <http://www.ofcom.org.uk/static/archive/ra/publication/ra_info/ra114.htm

Helpfully this is supposed to be on the www.radio.gov.uk site according to
the document, but that site points you back to www.ofcom.org.uk :-((
They have not got all their links updated yet.

However there is a Low Power RA Archive section that contains:-

<http://www.ofcom.org.uk/static/archive/ra/publication/interface/word-pdf/ir2030v1-2.pdf

It is only about 80KB so i can email it if you want.

The relevant table (in my copy) is Table 2.20 on page 26, part of which is
below:-
Categories Frequencies or         Radiated Channel      Music or
           Frequency Band         level    Bandwidth    speech
                                                        permitted
i          26.96 - 27.28 MHz       100 mW  10 kHz          No
ii         34.995 - 35.255 MHz     100 mW  10 kHz          No
iii        40.66 - 41.00 MHz       100 mW  10 kHz          No
iv         433.05 - 434.79 MHz      10 mW  25 kHz          No
v          458.5 - 459.5 MHz       100 mW  25 kHz          No

Any duty cycle is permitted

Reference Standard EN 300 220-1

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You will find the main users of 27MHz are in cheap toys usually made in China
for a world markets. Also nobody uses 27MHz unless they really have to,
because of the many other adjacent and conflicting devices, even CB radio.
These cheap toys have BINARY control controls.

459MHz is also allowed for any model, and gives a wider channel bandwidth
allowing better bit rates 4800bps becomes possible.

433Mhz is only very low power for telemetry back and reduces range for
anyone wanting to do communications feedback to control system.

--
Paul Carpenter        | snipped-for-privacy@pcserv.demon.co.uk
<http://www.pcserv.demon.co.uk/ Main Site
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Re: wireless serial Radio-Link
On Wed, 7 Jul 2004 23:06:13 +0000 (UTC), Paul Carpenter

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<http://www.ofcom.org.uk/static/archive/ra/publication/interface/word-pdf/ir2030v1-2.pdf
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Thank you, I've got it from the site.

   Vadim

Re: wireless serial Radio-Link
Thanks Paul,

I found the document. Looking at it, it seems that the 458MHz band is
most suited for helicopter control. I am not very sure but it looks
like as if the 458MHz band is not allowed in other european countries.

Does anyone know of a serial radio module that operates in the 27MHz
or 35MHz band?
(The 40MHz band is unfortunatelly only for land and water models).

Thanks,
Stefan

paul$@pcserv.demon.co.uk (Paul Carpenter) wrote in message
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Re: wireless serial Radio-Link
On 10 Jul, in article
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Look at International frequencies and their sources of information on
the site <http://www.ukrcc.org/ , these may help you.

This page may help you but does not list Germany, but list most countries
and is the Federation Aeronautique Internationale or part of Commission
International of Aero Modeling (CIAM)

        <http://www.fai.org/aeromodelling/frequencies/

For Germany this site might be useful <http://www.daec.de/ in German only.

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You are unlikely to find data modules specifically for these bands as
they generally PPM or PCM where the PCM is specific to radio control
by the Radio Control manufacturers. Unfortunately unles you find
someone with a multi-band module that covers the 35MHz band your are
going to find it difficult to find one meant for that band.

You may be able to find a radio control transmitter that can be modified
to input your own data stream via suitable lowpass filter. The receiver
may be more difficult.

I would check for the country you have in mind from its regulators what
can be done in the 459MHz band.

433MHz band is a pan-European (possibly global) telemetry band you can
use for feedback as it is telemetry.

--
Paul Carpenter        | snipped-for-privacy@pcserv.demon.co.uk
<http://www.pcserv.demon.co.uk/ Main Site
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Re: wireless serial Radio-Link
Thanks a lot.
The links helped. Looks like I'm tied to either 27MHz or 35MHz band.
If anyone knows of a radio module that can operate at those bands
please let me know.

Cheers, Stefan

paul$@pcserv.demon.co.uk (Paul Carpenter) wrote in message
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Re: wireless serial Radio-Link
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You can't put someone in jail just for thinking of trying something.
He might own the entire 400 meters air and ground space.  Even if he
carry out the experiment and did some damages, he should be responsible
financially.  If he did not intend to cost such damage, he should not
be in jail.

I wonder how many inventors would carry out their experiments if they risk
going to jail for.


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Re: wireless serial Radio-Link

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Like drinking a bottle of whisky and then driving around in a car
without brakes :-).

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Depending of the sped of the model aircraft, it does not require a
long communication failure to fly outside even this area. 10-40 s
should be enough.

The situation for a model helicopter may be different _if_ the
helicopter goes into a autoratoation mode upon loss of command link
and lands more or less intact close to the point of communication link
failure.
 
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What is the price of a dead person ?

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I think "criminal negligence" is term used in the US.

My point is, why use a risky method, when there are other methods
considered to be more safe (frequencies allocated for model aircraft
control) ?
 
Paul


Re: wireless serial Radio-Link
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That's fine if he is driving in his own land without anybody around.

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A well designed system should have emergency homing system and/or GPS.

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What if he is testing communication link/control in high interfence
situations?

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Depends on how that person got into the test area.

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Depends on the circumstances.  Appearancely, you already found him
guilty and handled down your sentense without any considerations.

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Risk assessment is very subjective.  Tell the Wright Brothers not to
fly when driving is just as good.

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