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Re: Re: Re: RE: Geo Opportunity



But I think your downlink budget assumes a single SSB user gets the full
10 watts of linear downlink.  I think we need to assume that there might
be as many as 5 simultaneous QSO's?  THus he only gets 2W of transponder
power, losing 7 more dB.  I think that's right.  I edited your link budget
below to this situation...

On Wed, 30 Jul 2003, Keith N6ORS wrote:

> These numbers assume 10watts of tx on the sat.
> A 5w rig with a wire on the uplink and arrow antenna on the downlink
> would make a nice portable psk-31/hellschriber setup. larger downlink
> antennas would make ssb workable.
>
> Keith (N6ORS)
>
> Uplink 10m
> TX power         10W    40 dBm
> TX Antenna Gain          3 dBi
> Polarization loss       -3 dB
> Resulting EIRP          40 dBm
>
> Path Loss at 10m      -153 dBm
> Receiver Antenna Gain    0 dBi
> Received signal       -113 dBm
> Required for 10dB SNR
>   in 3 KHz bandwidth  -119 dBm
> ------------------------------
> Margin                  +6 dB
>
> Downlink 2m
> TX power          2W    33 dBm  <== One of 5 users in 10W transponder
> TX Antenna Gain          3 dBi  <== when the whip is broadside to you
> Polarization loss       -3 dB
> Resulting EIRP          33 dBm
>
> Path Loss at [2m]     -167 dBm
> Receiver Antenna Gain   15 dBi  <== OSCAR class array
> Received signal       -119 dBm
> Required for 10dB SNR
>   in 3 KHz bandwidth  -120 dBm
> ------------------------------
> Margin                  +1 dB

de WB4APR@amsat.org, Bob

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