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| 5/27/2011 1:27 PM | |
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Posts: 272 Rating:
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Hi All, Is it possible to have a wireless communication for a distance of 4 kms. |
| 5/27/2011 1:38 PM | |
Joined: 3/21/2006 Last visit: 3/30/2025 Posts: 10239 Rating:
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Hello, Take a look at
If you keep to use Siemens look at Simatic S7-300 wireless?(almost the same issue but the required distance is less then yours. Other way is to use GPRS for the remote stations. And an Internet connection at the central location. In case of S7-300 SINAUT ST7 system http://support.automation.siemens.com/WW/view/en/23810112 In case of S7-200 SINAUT Micro solution: http://support.automation.siemens.com/WW/view/en/22537809 Best regards, Hristo Mihalev |
| 5/27/2011 1:38 PM | |
Joined: 10/7/2005 Last visit: 4/17/2025 Posts: 3047 Rating:
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Yes it is Prats, Voyager 1 is at time of writing some 17,408,281,206 km away from Earth (see HERE for more) and still wirelessly communicating so you can surely communciate wirelessly over 4 km, wouldn't you agree? If you give us some details about the applicationand what sort of speed you need, we may even be able to give you advise on equipment that does not require usage of a rather large Satellite dish. |
Last edited by: fritz at: 5/27/2011 1:41 PMfixed typos Cheers |
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| 5/27/2011 4:50 PM | |
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Posts: 947 Rating:
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Hi |
| 5/27/2011 4:56 PM | |
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Posts: 8946 Rating:
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Nice comparison. And here is the antenna equipment that you need! http://www.vla.nrao.edu/ |
| 5/31/2011 10:19 PM | |
Joined: 4/6/2006 Last visit: 2/5/2024 Posts: 604 Rating:
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Hi, I'm curious where the high value of 36 dB EIRP comes from since according to the country regulations for Australia the maximum value is 30 dBm in the higher 5 GHz channels (5.7-5.8 GHz) in the 2.4 GHz range the highest value is even less, 20 dBm. This values is something you can check on WLAN equipment suppliers webpages. At Siemens this can be checked at the latest firmware versions available for the Scalance W products. Or if you are an Apple iOS user checkout the freedot11wavelenapp in the iTunes Store. Then Siemens also supplies a tool which can help you calculating or a certain point-to-point link can reach far enough. With the data in the topic I calculated the following: Country: Australia Distance: 4000 meter Channel: 5 GHz no. 149 IEEE 802.11a Data Rate: 12 Mbps Selected Hardware: Scalance W784-1, 1 Meter Antenna Cable and an 18 dBi 5 GHz antenna. Then there should be an average reserve of 15.1 dB which should be suitable if the noise levels are low at the installation location. Please keep in mind that such calculations are only valid when you keep the Fresnel zone in mind. In this case it means that you need to place the antennas in a Line of Sight with a Fresnel Zone with a 7.2m Radius. This means that the there can't be on obstacle in between the antennas less then 7.2 meter form the LoS. This tool is available online at:Simatic Net Selection Tool I hope this enables you selection the correct products and the correct equipment for your project.
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Last edited by: O_Moderator at: 6/1/2011 7:48 AMlink edited Best regards, |
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| 6/1/2011 8:56 AM | |
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Posts: 139 Rating:
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Interesting what you say INS. I often get confused from all the different values that get published by suppliers or radio companies. But ultimately I think most refer to the ACMA standard which has been moved to the COMlaw website |
| 6/1/2011 10:05 AM | |
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Joined: 4/6/2006 Last visit: 2/5/2024 Posts: 604 Rating:
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Hi Anchobi, Thanks for the clarifications. I don't check local website for country approvals since those regualtions change often and are in most cases not clear. In certrtain cases even the maximum allowed EIRP is stated instead of the most common. I didn't take a to detailed look at the link you've provided but I can imagine that this 36 dB you've mentioned comes from a special regulation which have some very stricht boundaries, this is something which is often not communicated very detailed by the suppliers since it looks nice if you can say there is an abiliity to create a point-to-point link from several kilometers. But we should not forget that in (almost) every country in the world there is an agency which controls the frequency spectrum and they have specific regulations which a user and a product suppliet should obey´to. This also means that a device specific country approval is neccessary, the supplier should be able to tell which is allowed with his device. And yes there can be difference between device although they use the same standards. For Siemens devices I would suggest to have a look at: Siemens Wireless Approvals Or have a look at the CountryList.log which is available inside the Scalance device or with the latest firmware release. Download for SCALANCE W-700 firmware update: Download of firmware update V4.4.13 The Information you've found for Australia could be comparable but something in Germany which is called Broadband Fixed Wireless Access (BFWA) and which is reguated by the 'Bundesnetzagentur'. This is a special regulation which is for licensed products only and can only by used by Internet Service Providors to provide broadband internet access in areas where another infrastructure is not available (UMTS/Cable). The EIRP is 4000 mWatt (36 dB). To have it all summarize I would suggest to always contact the Supplier of the equipment they do exactly know which is allowed with their products. |
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