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link budget analyses a question

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andrishev

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Why the( SSPA )amplifier power is not included to these formulas?

received signal=(transmitter power)+(transmitter antenna gain)-(transmitter cab and conn losses)-(free space path loss+receiver antenna gain)-(receiver cable and con losses)

Why???:!::!::?::?::cry:
 

It is. The transmit power refered to in the formula is the power output of your SSPA in dBm. The formula you show is the typical one used to calculate freespace path loss between two locations.
 

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    andrishev

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will i add transmitter power out with SSPA out

TX power =transmitter 1dB compression point(transmitter output power)

or

TX power =transmitter 1dB compression point(transmitter output power)+SSPA output power
 

The only value you need is the total output power going to the antenna in dBm. Measure the final power output of your transmitter chain, the end that goes to your antenna, and use that value as the final power value for the formula. The 1db compression point value can be used if you like, or the linear value (before 1db compression point) can also be used. It won't make that much difference to the final answer.
 

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    andrishev

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do you know any web page or book or software for link budget analyses

especially long range 200km LOS Ku,C or X band systems
Also satellite communication systems
With high data rate like 45Mbps

i am working on UAV unmanned air vechile2s data links

so i need high data rate ;long range; high frequency
i must downlink video from airborne and also i have size and power limitations on airborne i must make link budget analyses so carefuly
 

In my first message I made a mistake and refered to the answer you get as the freespace loss. Your answer will be the received signal strength in dBm instead. Sorry for the mistake. Also, the formula for calculating the pathloss in dB is:

Loss (dB) = 32.4 + 20log(distance in miles) + 20log(freq in Mhz)
 

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    andrishev

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Try googling for Path loss analysis. Somewhere on the net is a path loss analysis for the Mars Pathfinder mission that you might find instructive. Excel is the tool I'm seen most used for this, so try filetype:xls at the end

Dave
www.keystoneradio.com
 

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    andrishev

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