Wireless Ethernet Network

[SK500]

Just to follow up on my last question, (

http://www.eng-tips.com/viewthread.cfm?qid=179647&page=1),

Are there any secure(relatively speaking) & broadband, fast means of transfering ethernet data wirelessly.

Short description of my application :
I’m working on a project that involves the transfer of data (Control signals) to a number of moving targets on a circular track; this will be an Ethernet network.


Thanks for your input in advance.

 

[MikeHalloran]

You mentioned RS-485, which is not real fast. Can you estimate an actual data rate? Do you need multicast? Full duplex? Half duplex? Unidrectional?

What possible threats cause you concern about security?

Do you have a space, weight or money budget?





Mike Halloran
Pembroke Pines, FL, USA

 

[davidbeach]

Wi-Fi.

 

[IRstuff]

ZigBee
Bluetooth

TTFN

Eng-Tips Policies FAQ731-376

 

[VEBill]

Critical question: How big is the track?

Bluetooth is very short range.

For very large tracks (2-mile car race tracks) it is likely that even WiFi would have insufficient reliable range without extreme special efforts in the antenna depertment. Moving targets limit the sorts of high gain antennas that might normally be used to provide useful ranges.

Some technologies also have problems with fast moving units. Their relative ranges keep changing and this can upset the critical timing of high speed TDMA networks.

 

[SK500]

REPLYto all questions:

Track is 35 feet in diameter.

Multi-cast. Full Duplex.

Possible threats...the usual wireless issues.

Budget...can pay for sophistication.

 

[SK500]

Circular track

 

[richs]

Hi-

WEP *SHOULD* be good enough security for transmitting.
For only 35 feet or so, 802.11B should be fine. This
is the standard WiFi. I suggest that you try it with
the test vehciles moving at speed. Typically, wifi is
NOT done with a moving client...... YMMV, but shouldn't
be that much of a problem.

There is a possiblity of interference with 2.4 G wireless phones. Equipment is inexpensive.

Security WEP, is not the most secure method of passing
data through a wireless network. However, SSL (secure
data layer, open source) will allow one to "layer" it's
encryption onto the packets. Changing the RSS key often
will usually thwart potential crackers of your data.
This will require a rather sophisticated computer on
the client side as well. However, if the embedded system
is using a common operating system interface, it should
be no trouble to find the drivers for an 802.11B type
USB dongle. An alternative would be a VPN (virtual
private network). These are usually NOT open source and
will require some fees from the supplier.

I will refrain from a suggested supplier as I have
affliation with one, but I'm sure that any from the
major players will be fine.

Leaky coax will not be required (from the original post)
as the wifi router will pass the signals.

Hope this helps.

Cheers,

Rich S.

 

[dpc]

Wi-Fi should work. Security is relative. There are an escalating series of option for security using Wi-Fi and it can be extremely secure if you want to spend the money.

 

[itsmoked]

Just remember all Ethernet stuff lacks determinacy - rather badly! Remember that Ethernet works of collision detection and a technique for waiting a random amount of time before retransmitting. Collisions cause completely random and unpredictable delays - constantly. If you need to talk to a bunch of things real-time you really should consider getting your own transceivers and writing your own protocol.

Your biggest bang for the security angle would be a non-standard protocol and the lowest power you can get away with.

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[MacGyverS2000]

Since the track is circular, and assuming a centrally located antenna, distance between antennas should remain relatively constant and therefore not upset transmission/reception.


Dan - Owner

http://www.Hi-TecDesigns.com

 

[Senselessticker]

I've been waiting for a couple of years to begin seeing posts about wireless control technology. I've heard about M2M technology (machine to machine).

I could be wrong, but I think Zigbee has the edge on the market for this kind of communication. And I'm fairly confident that the the IEEE has developed a standard especially for such applications (very similar to 802.11b).

I'm hoping I get to experience the day when twisted pairs are a thing of the past and motor control, lighting control, etc... is all accomplished by wirless M2M communication. Good luck with your application!

 

[pooslinger]

How about 900MHtz frequency hopping ethernet data radios. Your eithernet its self is less secure then the transmission through these radios. The radios are addresses to each other. If someone wants to intersect your data by trying to translate a 900 MHtZ signal, They really want it bad.

 

[itsmoked]

I can't believe how many details are missing here to make any kind of non-useless suggestions.

Come on SK500 get with it! We need some questions answered.

What latency are you allowed?
What data rate is required?
What power is available?
How many moving points?
What size is the data you need to move?
Does this have to be bidirectional?
What cost can you tolerate per point?
What speed are these moving things going?
How big can the transmitters be?
Etc.
Etc.

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[klaxon]

Freewave makes a pile of ethernet radios. I use them in a remotely operated vehicle with a several mile range.

There are ethernet and serial versions.

itsmoked is right. More info would be helpful to answer better, but head to

http://www.freewave.com/products/product-141.html>

and take a peek at the FR115E. It's available in a module form, as well as packaged. Not particularly expensive in terms I am used to.