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  #1  
Old 09-27-2005, 06:30 PM
Abbas
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Hello All, I just would like to know whether any of you used both High radio and Low radio on the same site before or not. Such that i am facing such case and i need to use both H/L radio on the same freq band on the same tower. If i can not do such thing i will apprecieate giving me more details or regulations.

Thanks
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  #2  
Old 09-29-2005, 12:05 AM
Jonnathan Romero Jonnathan Romero is offline
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Default Hi/Low

Hi,

It's possible to do it. There is no problem with that. There is no regulation for this situation.

Hi/Low Criteria is kept by companies in order to have an standard. If I use in a hill Hi Tx frequency, it's good for other companies to use same criteria. For everybody.

But...

If there is no option, like a very crowed hill, full of towers, you must be careful with frequencies. You have to perform a frequency sweep for find out what are the channels that the other companies are using. Avoid that channel as long as you can. Remember that propagation in near field is not the same.

If you HAVE to use the same tower, the same channel, I recommend you to separate the antennas as far as you can. I recommended a link in Jamaica that use Tx1:Ch3' Rx1:Ch3, and there is another company transmiting almost the same azimut but Tx2:Ch3 Rx2:Ch3'. The antennas are at 17mAGL and recommended at 60 mts AGL. The another company signal doesn't get into our company receiver (Tx2:Ch3 into Rx1:Ch3). There is no interference at all between those links. The only thing that you have to think about is do not receive the same channel in the same tower.

There are practical procedures to know if you have that interference due reflections or near field radiation. But, only if is really needed, I would recommend it.

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  #3  
Old 09-29-2005, 11:30 AM
Emma
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I can check it for you first let me know your spectral occupation, duplex separation and Tx1-Rx2 difference on the site.
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  #4  
Old 09-30-2005, 02:57 PM
ABBAS
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Thanks a lot Romero and Emma,

I will send you the required info by Sunday. Thanks a lot for your interest.
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  #5  
Old 10-04-2005, 03:43 PM
Emma
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Still waiting to hear from you. Include also information on angular discrimination bewteen the antennas and antenna models
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  #6  
Old 10-04-2005, 10:02 PM
abbas
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Hello i am sorry for the dely,

TX 23177 AND RX 22169

DUPLEX IS 1008

NEC RADIO PASSOLINK

ANDEREW ANNTENNA 1.2 SPHP

DISC ANGLE IS ABOUT 20 DEG
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  #7  
Old 10-05-2005, 10:54 AM
emma emma is offline
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I need the second Tx/Rx pair. I believe your spectral occupation is 3.5mhz.
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  #8  
Old 10-05-2005, 09:32 PM
ABBAS
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Hello,

This is the only freq channel i am looking forward to reuse. One link is H/L and the other link is L/H.
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  #9  
Old 10-06-2005, 10:36 AM
 is offline
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You cannot reuse this channel with the angular disscrimination you have. The worst case would be when you make H/L and L/H combination on this site. Then you would have TR coupling on this site ie Tx of one link would satuarate the Rx of the other link and you shall loose bothe links. Cross polar discimination would not help you here as the antenna you have can only provide 30dB isolation. My adivise is to either get another channel or consider a linear topology.
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  #10  
Old 10-06-2005, 09:49 PM
Abbas
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Hello,

So do you think that i can use 22183/23191 on the same site with 23177/22169 on the same side. Shall i succeed with this. Thanks a lot for your interest and feed back.
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