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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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----
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