Calculation Of EIRP

EIRP stands for Effective isotropic radioated power , the power which is radiated out from antenna .Every country has different EIRP limitations.

Power calculation 10s and 3s rule will play important rule in EIRP calculation, For every 3db increase in power the transmit becomes double , to calculate EIRP add all gains and deduct losses from radio to antenna .

let us say radio has a tx power 25dbm and it is attached to the antenna woth the gain 3 dbi .
25 dbm in mw will be approx 250 mw and with no other losses , the EIRP i this case will be 25+3 = 28dbm or 500mw.

If there is some losses in the physical connections lets say 1db then EIRP will be 27dbm.

To limit the EIRP the transmit power of radio and antenna gain has to be adjusted.

TRANSMIT POWER CALCULATIONS

For every 3 db increase in power the equivalent power in mw gets doubled i.e if initial Tx power is x dbm equivalent to y mw and if we increase the power to (x+3)dbm then it will be equivalent to 2y mw it means the Tx power doubles in mw for every 3db increase in power and similarly the Tx power becomes half in mw for every 3db decrease in power.

Similarly power becomes 10 times in mw for every 10 db increase and becomes 1/10 in mw for every 10 db decrease.

As the above calculations are valid only for 10db and 3 db it is called as rule if 3s and 10s.

Note : Above calculations is very useful when designing the wireless network but for product and circuit designing logarithmic calculation is best.

Importance of Lat-Long GPS Co-ordinates.

Lat/Long are the very basic components when we talk about point to point wireless installation.

With lat long we can find out the exact air distance of the link , We can get the elevation profile with google earth , we can the alignment direction of the radios from each direction.

The best way to plan for any point to pint link is to do a LOS path survey , when planning with the microwave frequencies , We must have a clear LOS to give a reliable link connectivity.

Then there are other things line link budgeting , Site readiness etc but importance of lat long cannot be ignored.