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  #1  
Old 12-02-2003, 04:27 PM
Reggie Reggie is offline
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Just consider a 65 km path with average terrain and average climatic conditions (no special case) in the 6 GHz band.

When I design the path with only one 12 ft antenna on each side, I get approximately 99.999% annual availability and 99.995% worst month availability.

Then, I decided to redesign the same path with space diversity antennas and I get the same availability results with two 8 ft antennas on each side.

Now, which other criterias must I consider to decide which configuration to install in the field?

I am not looking for mechanical considerations, such as the tower loading, but for RF criterias that I can look at when I design the path. Many people tell me that for a 65 km path I should install diversity antennas, but they are not able to tell me why!

So, I would like to get theoretical considerations to take into account when I design the paths, because we all know that for each single antenna configuration we can get a space diversity antenna combination that will produce the same reliability results, no matter the distance!

Thank you all in advance!
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  #2  
Old 12-08-2003, 10:26 PM
Terry Roberts Terry Roberts is offline
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Reggie;
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  #3  
Old 12-08-2003, 10:28 PM
Terry Roberts Terry Roberts is offline
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Reggie; I have a paper put out by Alcatel explaining all the different diversity systems and networks. It contains all the formulae required would that help?
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  #4  
Old 12-09-2003, 02:57 AM
iman
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Hai Reggie. I don't want to give a comment to your question because i also still learning. I just curious how do you perform the LOS survey for 65 km path length. Did you do only in a (digital) map ? Or you also go / send a surveyer to the both site ? I mean how did you see the far end.

Thank you in advance and Regards,

iman
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  #5  
Old 12-09-2003, 01:05 PM
Reggie Reggie is offline
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Dear Terry, you could send your Alcatel document at the following address: rejean.gosselin@sct.gouv.qc.ca
I greatly appreciate your collaboration and I will give you news!

Dear Iman, the survey is only done from a very precise terrain database (about 1 to 3 meters in elevation)!
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  #6  
Old 12-20-2003, 06:39 PM
Bhaskaran Bhaskaran is offline
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Default Space Diversity

Dear Terry Roberts,


Could you please send that paper put out by Alcatel explaining all the different diversity systems and networks to my following mail ID.

bhaskaran_sk@yahoo.co.uk

Many thanks for your kind help.

Bhaskaran
Muscat
Oman
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  #7  
Old 01-12-2004, 11:22 AM
Anuj
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Default Alcatel Details

Dear Bhaskaran
You can get in touch with me if you need any details for the Alcatel systems.
Thanks
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  #8  
Old 01-30-2004, 02:59 PM
Pierre Thomas
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Default Space Diversity

This technique is effectively recommended for long distance hops because:
- propagation conditions are affected by atmospheric layers (boudary layers)
- this is simply introduced in the Link budget calculation through the multipath fading occurence factor
- you should then look the tables of RECOMMENDATION ITU-R P.453 to evaluate the ducting potential occurence, strength, width both for surface based ducts and elevated ducts
- depending on the quality performance evaluation without space diversity, you may appreciate the resilience of the link to the non standard propagation conditions

Of course, if you change your design from unprotected to space diversity, you will notice deep performance improvement and depending on the effective fading margin, you may reduce antenna size and even install top of the tower a smaller antenna (the antenna dimension and related gain are incorporated in the diversity improvement calculation)

Last but not least, the performance of the radio is essential in term of hitless switching, AGC dynamic variation, and channel equaliser

Be aware that many parameters have to been considered to ensure reliable link budget calculation.
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  #9  
Old 03-05-2004, 04:15 PM
Alf Alf is offline
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Hi, Terry could you send me this information to jaayalam@netscape.net.

Thank you
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  #10  
Old 03-31-2004, 04:43 PM
Gustavo Gustavo is offline
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Default Alcatel files

Hi Terry ,

Coul you please send me the Alcatel document to my e-mail gustavo_berasategui@hotmail.com

Thanks ,
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