interface a micro to wireless modem(ethernet)

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7rots51

Joined: 17 May 2002
Posts: 1427
Helped: 14

19 Oct 2003 18:48 interface a micro to wireless modem(ethernet)

Hi

Is it possible to interface an embedded board(include a microcontroller like as AVR ) to ultima 3 modem from wi---lan company?

This wireless modems are working at 2.4ghz and 5.8ghz and thier interface port is ethernet 100mbps.The range of this modems is up to 75KM and the antenna is integrated with it.

Please specify the methods for send/receive data with them by a microcontroller system.

roli

Joined: 29 Apr 2001
Posts: 846
Helped: 1
Location: 'SiliconWafer' Island

19 Oct 2003 18:58 Re: interface a micro to wireless modem(ethernet)

You must be wrong - range of 75Km ?
The interface should be a straight forward 802.3 MAC - I presume....
[e.g. - the modem should look like a PHY]

cancel

Joined: 27 May 2001
Posts: 286
Helped: 11

19 Oct 2003 20:45

sure .. most of wlan modems offers transparent ip connectivity iow ip bridge so try any eth project e.g. ethernut or web51. i also would doubt about range ... espacialy with integrated antennas and allowed erp 20dbm

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flatulent

Joined: 19 Jul 2002
Posts: 4875
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Location: Middle Earth

19 Oct 2003 21:49 range

With 100 M data rate, the range is more likely to be 75 m best case maximum. 802.11 devices with 10 M data rate and 10 dBm of power rarely go 75 m except if they are on two building tops with no obstructions between them.

cancel

Joined: 27 May 2001
Posts: 286
Helped: 11

20 Oct 2003 9:14

you can have severel km link but you need to follow some conditions:
direct visinity
externel antennas
a lot of erp ;0)
i saw hop with 26 bdi antennas with distance abt 7km in 2.4ghz 802.11b (10mbps), of cause you have +46dbm erp which is much much more than allowed

AL0117

Joined: 25 Jul 2003
Posts: 237
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Location: dracu-la-nd

20 Oct 2003 10:21 Re: interface a micro to wireless modem(ethernet)

at 2.4 GHz the pathloss for 1 km is about 99dB, doubling the distance the loss increase by 6 dB. So for the 75 km the loss should be about 141-147 dB. 75 km is a bit more. In my opinion with the legal ERP and 20-30 dBi antennas is not quite feasible.

regards, Al

7rots51

Joined: 17 May 2002
Posts: 1427
Helped: 14

20 Oct 2003 18:19 Re: interface a micro to wireless modem(ethernet)

You can find more info at w*w.wilan.com about ultima 3 modems.They have pdf on their modems.

But my aim is not range,I want to know is it possible to interface a microcontroller with them and send/receive data with that wireless modems?How?

flatulent

Joined: 19 Jul 2002
Posts: 4875
Helped: 324
Location: Middle Earth

20 Oct 2003 18:35 Re: interface a micro to wireless modem(ethernet)

They claim 10/100 BaseT data connection. They claim that this product operates on 802.16 protocols. That should give you information on how to make the system work.

Their up to range figures are for free space. Any products that are on buildings will be much more limited. Ground wave is highly attenuative at these frequencies.

cancel

Joined: 27 May 2001
Posts: 286
Helped: 11

20 Oct 2003 18:41

once again .. you can use any ip stack project with mcu ... you have to send either tcp or upd packet form your first mcu board to ip adress of your other mcu board. the wireless modems will do the rest for you .. they will bridge your ip networks ...

regards

cancel

asena

Joined: 23 Jan 2003
Posts: 73
Helped: 3
Location: Portugal

20 Oct 2003 19:46

[quote="cancel"]you can have severel km link but you need to follow some conditions:
direct visinity
externel antennas
a lot of erp ;0)
i saw hop with 26 bdi antennas with distance abt 7km in 2.4ghz 802.11b (10mbps), of cause you have +46dbm erp which is much much more than allowed[/quote]

Ive done a link of 40km with a 24dbm dish and a yagi uda, 2.4ghz, 802.11b 11Mb with 50-60% quality !!

I was using the Linksys Wireless bridge on both ends !!

asena Cool

cancel

Joined: 27 May 2001
Posts: 286
Helped: 11

22 Oct 2003 13:13

to asena:

i used linksys also .. not problem for longer distances also .. but i needed very high reliability ... good advise: linksys is switching to slower spped too early .. iow it has still good signal but decides to decrease speed .. so disable auto fallback ;0)