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Re: RE: Geo Opportunity



Bob,

Why do you want to use a linear cable TV amplifier? I have never seen a 
cable TV amplifier that can do more than 1 watt or so. These hybrids are 
very linear but are normally run with levels of 0dBm or so per tone. They 
can handle 132 channels spaced 6 MHz apart with good distortions. The P1 dB 
is around 28 dBm. Why wouldn't a mitsubishi style module work for this?

Pieter

>From: Bob Bruninga <bruninga@usna.edu>
>To: kgschaffrath@beckman.com
>CC: amsat-bb@AMSAT.Org
>Subject: Re: [amsat-bb] RE: Geo Opportunity
>Date: Wed, 30 Jul 2003 15:54:23 -0400 (EDT)
>
>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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