wireless serial Radio-Link

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

I used Aerocomm modules. Though it was not mobil application. But I found it
easy to use and convenient.
Aleks.
"Stefan" <news@stefan-strobl.de> wrote in message
news:e33936f6.0407020759.6e1810ec@posting.google.com...
> 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

Aleksandr Baranov wrote:
> I used Aerocomm modules. Though it was not mobil application. But I found it
> easy to use and convenient.
> Aleks.

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

"Stefan" <news@stefan-strobl.de> wrote in message
news:e33936f6.0407020759.6e1810ec@posting.google.com...
> 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

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

-- 
----
Morten
Raider of the Lost Electron

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.

"Glenn" <monkeytech@sympatico.ca> wrote in message
news:JFnFc.196193$207.2089108@news20.bellglobal.com...
>
> Aleksandr Baranov wrote:
> > I used Aerocomm modules. Though it was not mobil application. But I
found it
> > easy to use and convenient.
> > Aleks.
>
> What Aerocomm modules did you use?  And what kind of
> throughput and latency were you getting?
>

On 2 Jul 2004 08:59:23 -0700, news@stefan-strobl.de (Stefan) wrote:

>Hi,
>
>I'm looking for a wireles serial radio-link that runs Full-Duplex.

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.

>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.

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

> >Hi,
> >
> >I'm looking for a wireles serial radio-link that runs Full-Duplex.
> 
> 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) ?

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.

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

That is not acceptable in my relatively small helicopter.

> What data rate do you need ?

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

> What reliability do you need, 90 %,99 %, 99.9 etc of the time ?

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.

> Do you always have a line of sight path to the mobile unit ?

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

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

Thanks a lot.

"Raider of the Lost Electron" <invalid@spam.no> wrote in message news:<2duFc.1204$v04.25167@news2.e.nsc.no>...

> 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)

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

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

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

Thanks,
Stefan

On 5 Jul, in article
     <e33936f6.0407050550.1a5101d@posting.google.com>
     news@stefan-strobl.de "Stefan" wrote:

>> >Hi,
>> >
>> >I'm looking for a wireles serial radio-link that runs Full-Duplex.
>> 
>> 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) ?
>
>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.

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.

>> If you insist of using a single frequency band,be prepared to use
>> duplex filters, which are big, heavy and expensive.
>
>That is not acceptable in my relatively small helicopter.
>
>> What data rate do you need ?
>
>The data rate is not crucial. As little as 4.8kb/s or even 1.2kbaud
>would do.

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.

>> What reliability do you need, 90 %,99 %, 99.9 etc of the time ?
>
>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.

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!

>> Do you always have a line of sight path to the mobile unit ?
>
>The heli will be operated obviously outside but a tree inbetween
>shouldn't be a problem.

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

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

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.
 
-- 
Paul Carpenter		| paul@pcserv.demon.co.uk
<http://www.pcserv.demon.co.uk/>        Main Site
<http://www.gnuh8.org.uk/>              GNU H8 & mailing list info.
<http://www.badweb.org.uk/>             For those web sites you hate.

news@stefan-strobl.de (Stefan) wrote in message news:<e33936f6.0407050554.4704fdc0@posting.google.com>...
> "Raider of the Lost Electron" <invalid@spam.no> wrote in message news:<2duFc.1204$v04.25167@news2.e.nsc.no>...
> 
> > 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)
> 
> The datarate is not critical. As little as 1.2kbaud would be ok.

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.


> 
> > 
> > If your datarate requirement is low enough a duplex link that emulate
> > full-duplex as seen from either  should be OK?
> > 
> > 
> > HTH
> 
> Having an emulated full-duplex makes the protocol more difficult and I
> ideally would like to have some real-time behaviour.
> 
> Thanks,
> Stefan