Recommended Signal strength for good signal.

[singhsaju]

Hi

What is the recommended signal strength for Cisco AP 1310 with external 13 dBi antenna ? I am seeing -86 dbi signal strength .

Any help will be appreciated.

[bcolvin]

without knowing the distance to calculate the path loss you can't say if -86 is good or bad. according to this document below at -86 you should b able to operate at 12Mbs.

http://www.cisco.com/en/US/prod/collateral/wireless/ps5679/ps5861/product_data_sheet09186a00802252e1.html

You can use the following document to calculate what you signal shoud be by pluging in the numbers.

http://www.cisco.com/en/US/products/hw/wireless/ps458/products_tech_note09186a008009459b.shtml

remember if you ar using both B and G data rates you will need to set the radio power for both radios the same. most signal strength readings are based on the Beacon transmitted by the AP. So if your B readio is Beaconing at 100Mw(20dbm) and you have the G data rates enabled the data portion of your packet will transmitte at 30Mw(15dbm) 5db less the the beacon this can cause the many retries as the AP transmitts at lower data rates to get the packet through.

HTH

Bill

[singhsaju]

Bill,

Thanks for the reply . The distance between the two antenna is 2 kms only. so is -86dbm a good signal ? what is recommended signal strength for the 2 kms ?

Thanks,

[soularch23]

Hi Sing:

There are numerous path loss calculators on the web (google search 'path loss calculator'). I found this simple to use calulator: http://www.distributed-wireless.com/calculators/pathloss_RSSI.html

It states the signal should be -77 based on 200mW, 6dbi antennas, and 0dBi rx gain.

Keep in mind, however, that a good signal (based on throughput) depends on the noise floor also...a -77 signal is NO good if there is noise at -80 and you are trying to maintain 18Mbps.

PS - I just recalculated using 13dBi antenna as you indicated, and 200mW, and the signal should be -70.

[dennischolmes]

Signal to noise is a better indicator. What is your SNR? 20 or better should be able to function.

[singhsaju]

Hi

SNR is 17dbm.The distance is 2.0 kms .

I am also suspecting the coax cable between Yagi antenna and wireless bridge .Its RG-59 cable. This might introduce significant loss of signal.

Thanks,

[dennischolmes]

17dbm is an issue. Try low loss cables and enhance the antennae if necessary with more directionality and gain.