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Power setting for our Ku Transmit System

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Ex Member
Ex Member


Jan 5th, 2011 at 8:07am  
Sir is there an appropriate setting for power output level on each equipment on our Ku transmit system? Currently our modem is set to -20dBm which is its minimum power level, our upconverter is set to attenuation level of  22dB its maximum is 30dB and our Power Amplifier is set to 23 dB and has a maximum level of 25 dB. We achieved our desired power output in coordination with our satellite operator in this setting.
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« Last Edit: Jan 6th, 2011 at 12:35am by N/A »  
 
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Eric Johnston
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Reply #1 - Jan 5th, 2011 at 9:25am  
I would recommend avoiding having anything set to either its minimum or maximum.

Reasons (not in any particular order):
It limits the direction of any future possible in-service adjustments.
It increases the possiblility of high noise-floor or overload problems.
Setting anything to minimum value increases the risk of an accidental 10, 20, 30 or 40 dB increase.
Equipment works better in the middle of its design range (less noise, better linearity, less intermodulation).

If you have a high power amplifier operating at very low power output be very careful not to accidentally increase the input.  Consider putting a fixed attenuator on the input to the HPA.  

If you have a combining network on the transmit side, so as to allow multiple transmit modems, then terminate all unused inputs with 50 or 75 ohm terminations.  

If any manufacturers are reading this, note my suggestion that typed-in or keyed-in power output or attenuator settings should only be changeable upwards in small 1 or 2 dB steps. It should not be possible in the firmware to increase modem output levels in large steps.

Useful reference: Satellite Users Interference Reduction Group

Best regards, Eric.
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Ex Member
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Reply #2 - Jan 6th, 2011 at 12:36am  
Thanks sir, your reply has a big help to me.
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