satelitte eirp
时间：04-10
整理：3721RD
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actually i am having some trouble with transponder power distribution among different carriers.
Actually i found the following text on the net and have also seen that practically implemented in some companies for link budgets.
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Satellite downlink EIRP
Referring to the satellite transmit downlink coverage pattern, the saturated EIRP on each contour will be specified. For example +36 dBW at beam centre and +32 dBW at the -4 dB contour.
Assuming a multi-carrier transponder operating point of -10dB input back off and -4.5dB output back off, the operating downlink EIRP, on the -4 dB contour will be +36 -4 -4.5 = +27.5 dBW. This refers to the whole transponder output power and is the aggregate of all the multiple small carriers present.
For a 2 MHz slot, out of a transponder bandwidth of 36 MHz, the available downlink EIRP will be +27.5 -10 log(36/2) = +15 dBW . This assumes that the total power is more or less evenly divided according to bandwidth. In practice you can buy more power if you need a high power spectral density carrier, but on average other people will have to have lower power per unit bandwidth to keep the total operating point under control.
You could buy say 2 MHz bandwidth and the matching +15 dBW of power and then concentrate all the +15 dBW into a narrow carrier of say 250kHz bandwidth, while leaving 1.75 MHz of your bandwidth unused. You might do better to broaden your carrier with as much more error correction bits as possible.
So put 15 into the link budget for the downlink EIRP
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Is the above approach right? and if yes this means that i am taking the maximum EIRP to be the total EIRP the sat antenna is transmitting
i.e. EIRPmax by sat = EIRPtotal by sat
that way i can relate the power used by the xpdr directly with the eirp and using the EIRP instead of power like in the above text i found on the net.
My case is that i am using 1 HUB and various remote sides. the problem comes when i divide the transponder power among all the carrier, the OPBO that i leave on the xpdr is equal to the EIRP for my BW - the max EIRP at the bore center of the satellite
The footprints of a satellite shows various EIRP foot prints so do i have to add all the foot prints to achieve the total EIRP so i can chk how much EIRP i can use according to my BW, distributing among the carriers or there is some other approach.
please help
Actually i found the following text on the net and have also seen that practically implemented in some companies for link budgets.
////////////////////////////////////////////////////////
Satellite downlink EIRP
Referring to the satellite transmit downlink coverage pattern, the saturated EIRP on each contour will be specified. For example +36 dBW at beam centre and +32 dBW at the -4 dB contour.
Assuming a multi-carrier transponder operating point of -10dB input back off and -4.5dB output back off, the operating downlink EIRP, on the -4 dB contour will be +36 -4 -4.5 = +27.5 dBW. This refers to the whole transponder output power and is the aggregate of all the multiple small carriers present.
For a 2 MHz slot, out of a transponder bandwidth of 36 MHz, the available downlink EIRP will be +27.5 -10 log(36/2) = +15 dBW . This assumes that the total power is more or less evenly divided according to bandwidth. In practice you can buy more power if you need a high power spectral density carrier, but on average other people will have to have lower power per unit bandwidth to keep the total operating point under control.
You could buy say 2 MHz bandwidth and the matching +15 dBW of power and then concentrate all the +15 dBW into a narrow carrier of say 250kHz bandwidth, while leaving 1.75 MHz of your bandwidth unused. You might do better to broaden your carrier with as much more error correction bits as possible.
So put 15 into the link budget for the downlink EIRP
/////////////////////////////////////////////////////
Is the above approach right? and if yes this means that i am taking the maximum EIRP to be the total EIRP the sat antenna is transmitting
i.e. EIRPmax by sat = EIRPtotal by sat
that way i can relate the power used by the xpdr directly with the eirp and using the EIRP instead of power like in the above text i found on the net.
My case is that i am using 1 HUB and various remote sides. the problem comes when i divide the transponder power among all the carrier, the OPBO that i leave on the xpdr is equal to the EIRP for my BW - the max EIRP at the bore center of the satellite
The footprints of a satellite shows various EIRP foot prints so do i have to add all the foot prints to achieve the total EIRP so i can chk how much EIRP i can use according to my BW, distributing among the carriers or there is some other approach.
please help