Re: [amsat-bb] AO40 DX packetcluster spots

["Jeff Griffin" <kb2m@xxxxxxxxxxx>]

That sound's great Bob, it ain't up yet ? ; )  Is there anyway to donate
time, or money to the project?

73 Jeff kb2m

----- Original Message ----- 
From: "Bob Bruninga" <bruninga@usna.edu>
To: "Jeff Griffin" <kb2m@comcast.net>
Cc: <amsat-bb@AMSAT.Org>
Sent: Sunday, August 03, 2003 11:47 AM
Subject: Re: [amsat-bb] AO40 DX packetcluster spots


> Jeff Griffin wrote about DX spots for SAT activity:
>
> > I had hopes of quicker DXspot turnaround then observed at AMSAT BB for
> > LEO spot's.  (4 to 30 mins) TTP.
>
> Actually, that would be a good use of the low-duty-cycle high-power packet
> digipeater I am proposing for the SuperGeo bird.  It would serve everyone
> in the hemisphere! Its routine BEACON gives the xponder schedule and
> one-time UI packets can announce SAT DX spots.
>
> > I don't see the satdx idea working on the LEO's!
>
> Hummh.  The SuperGeo scheme would..
>
> > I'm traveling alot at work lately, 3 to 4 week a month, and I
> > sometimes live in places that don't have internet service...
>
> With the high-power (low dutycyle) digipeater downlink from SuperGeo, then
> while you are driving, you will get theDX spots on the front panel of your
> D7/D700/2000 Kenwood!  If you see one you want, pull over and stick your
> arrow out the window...
>
> Hummh... AH, to dream....
>
> WB4APR
>
> ------------------SuperGeo conecpt: ---------------------
> Date: Sat, 2 Aug 2003 19:51:27 -0400 (EDT)
> From: Bob Bruninga <bruninga@usna.edu>
> Subject: Re: [amsat-bb] New baseline for GEO (rev-1)
>
> SuperGeo (rev-1)
>
> New KEY elements:
>  1) Full time Mode-B U/V linear transponder for SSB cw and PSK31 though it
>     Goal is to work it with a portable arrow even it means many
>     restrictions.
>
>  2) Part time 50W single channel FM donwlink for special events hearable
>     on any mobile but operated usually as a directed net.
>
>  3) APRS Packet bulletins once every 5 minutes on 144.39 posting the
>     schedule of events to all mobiles on the continent (and the European
>     APRS frequency when it drifts over Europe)
>
>  4) Occassional AX.25 digipeating for special events SatDXspots and
>     wilderness travelers with downlink on 145.825 receivable by mobiles.
>
> The purpose of #3 is for the thousands of APRS mobiles, once every 5
> minutes they will receive a packet shwoing them ON THE FRONTPANEL of their
> radio, the next scheduled event on the FM transponder.  THink of this as a
> "tiny web-page" of real-time info on what the HAM community is doing with
> this asset.  Due to congestion on the main APRS frequency, you will not
> get all of these.  But you only need one to be updated.  It will go to
> your DX list so it doesnt detract from your other messages, and also so
> that any Kenwood 2000 rig will also display it on its front panel too.
> Just anytime you are in your car, just push the DX button and your radio
> will show you what is coming up next and when!  On the 145.825 packet
> downlink, you will get Sat-DX-spots.
>
> Now, can someone nail down the limtations we will have to make to make a
> Linear Transponder that can only have 10 Watts of AVERAGE DC power and yet
> can be comfortably worked with a portable ARROW set up.  Even if it has to
> be a single channel, just tell me what it takes.  I dont have time to do
> this detail, with the other 2 satellites I am on deadlines for.  But now I
> think I know what we can do for transponders.  Here is a review of the
> situation:
>
> ORBIT:     Drifting GEO (slightly supersync)
> ATTITUDE:  None (tumbling, rates unknown)
>
> MISSION: is to provide one full time (thou minimal) linear mode B
>          transponder, and part-time, one AX.25 packet, and one FM voice,
>          comm channel for special HAM radio applications.
>          Packet is for direct-to-user-front panel real-time bulletins
>          about scheduled operations and occasional special events.
>          The FM voice (and, if necessary the linear transponder) will
>          always be under the control of a scheduled Net Control for
>          the given event.  Duty cycle will be low.
>
> ACCESS:  THe linear transponder is on full time (we hope).  The transmit
>          duty cycles for the FM modes are low.  The FM Voice
>          will only be activated to support special events on schedule.
>          Schedule will be available live on the 5 minute packet beacon.
>
> GROUND STATIONS:
>    USER: We want a user with an ARROW antenna and SSB rig to be able
>    to hear at least one channel on the Linear downlink and anyone with
>    an FM rig and an arrow to work the FM transponder when activated.
>
>    NET CONTROL:  Must also be operable portable for special events.
>
>    MOBILE:  A mobile with a center-roof 57" roof mounted whip (3/4 wave)
>    can receive the packet bulletins direct at middle latitudes on the
>    existing APRS channels.  And holefully hear the FM downlink when used
>    (on a different freq).
>
> TRANSPONDER DESIGNS:
>
>    PACKET:  Dual redundant 50W Packet Transponders for TT&C, Bulletins,
>    and special users (those with the need)... Two separate digipeaters
>    Operating independently on their own orthogonal monopoles gives 3 dB
>    link advantage.    Downlinks are on 145.825 and the continental
>    APRS freq.  Uplink is on 70cm and will take lots of gain and power.
>
>    FM VOICE:  2m Downlink is just at 12 dB SINAD for .18 microvolt
>    receiver using a 3 element Arrow style antenna.  User should have 6
>    elements for better copy...  Uplink takes 50W to the Arrow, but you
>    only make it in when satellite tumble favors you. (50% of time?)
>    Higher power base stations can do better.  Downlink is on 2m.  Uplink
>    is on 70cm. (must use external diplexer on ARROW!)
>
>    Linear transponder is limited to whatever it takes to be able to
>    leave it on all the time and work it on an ARROW.
>
> This is not the ideal spacecraft, but it is what we could do
> off the shelf if given the opportunity... Here are the link budgets I
> came up with for the FM parts.  Someone else can detail the linear part.
>
> DOWNLINKS to an ARROW ant   2m AX.25 and FM voice
> --------------------------  ---------------------
> TX power        50 Watts     47 dBm
> TX Antenna Gain               0 dBi
> Polarization loss            -3 dB
> Resulting EIRP               44 dBm
>
> Path Loss                  -167 dB
> Receiver Antenna Gain        10 dBi (arrow) 5 or 7 dBi for mobile
> Received signal            -113 dBm
> Required for 12db SINAD:             -121 dBm
> Good TNC needs:            -119 dBm
> Sky noise                     3 dB      3 dB
> -------------------------  --------  --------
> Margin                        3 dB      5 dB (3 or 5 dB worse for mobile)
>
>
> Again, for the SPECIAL usages there will be two uplinks, one for net
> control (priority) and one for the net...
>
> Correct me please if I have it wrong, and someone please review everything
> posted so far and give a good LINEAR link budget including whatever
> constraints are required to make it work for the Arrow portable.
>
> Thanks
> de WB4APR@amsat.org, Bob
>
>
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>

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