Re: [amsat-bb] RE: Geo Opportunity

[Bob Bruninga <bruninga@xxxxxxxx>]

On Wed, 30 Jul 2003 kgschaffrath@beckman.com wrote:

> The downlink dosn't look bad. Actually it looks pretty good.
> especially if we can get about 10dbw for the transponder.
> Its the Up link that would be murder, without any antenna gain
> on the sat you would need lotsa kilowatts on the groundstation
> to get a reasonable return signal.

But, not on 10 meters as the uplink band.  the 14 dB pathloss advantage
really helps...  For any discussions please, we need to see the full link
budget in any email discussions so we can all see what one is talking
about.  Use this format:

Uplink 10m
TX power         25W    43 dBm
TX Antenna Gain          3 dBi
Polarization loss       -3 dB
Resulting EIRP          43 dBm

Path Loss at 10m      -153 dBm
Receiver Antenna Gain    0 dBi
Received signal       -110 dBm
Required for 10dB SNR
  in 3 KHz bandwidth  -119 dBm
------------------------------
Margin                  +9 dB

Downlink 2m
TX power         5W     34 dBm
TX Antenna Gain          3 dBi
Polarization loss       -3 dB
Resulting EIRP          34 dBm

Path Loss at 70cm     -167 dBm
Receiver Antenna Gain   15 dBi
Received signal       -118 dBm
Required for 10dB SNR
  in 3 KHz bandwidth  -120 dBm
------------------------------
Margin                  +2 dB

But we still need someone to identify an off-the-shelf
ultra-linear Cable TV AMplifier usable at 2 Meters.
And how much power is available from them?

Bob, WB4APR


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