[amsat-bb] Secondary mission ideas

Wed Oct 30 00:14:22 UTC 2019

Idea 1:  Crosslinks
Something (anything) with crosslinks...... Big goal would be to go for DX records via intentional crosslinks for voice/packet/telemetry/(maybe even telecommand) relay.

If there is a tunable uplink frontend, (and its allowed from a regulatory perspective, so maybe fixed downlink freq, tunable uplink freq)....You mentioned 2m down, so my guess is UHF up?  Idea would be to relay voice/packet/maybe TLM from birds with a UHF downlink....Maybe go as far as regenerative transponder instead of bent pipe....easy enough for FM on a 'single frequency' (in quotes because Doppler...) could be trickier if single sideband relay and there are multiple signals in the passband.  So maybe regenerative for FM relay and/or packet relay, bent pipe for sideband relay.

......and if its tunable, it could be changed around 'seasonally' as orbits change and the chances of a relay increase or decrease for a particular bird.  Another fun application could be helping 'hurt' birds.....maybe something up there is still transmitting, but the finals on the PA are blown......if you could get a receiver close in.....maybe it could hear it and relay the data.......

Same idea for birds with hurting RX if they could tune their 2m downlink around (but that's probably a tougher sell from a regulatory point of view).  Imagine if they could TX at UHF (I know they can't, just an analogy here...). Tune to 435.300 MHz......get in 'close' to Fox-1C, and relay a couple of command station commands via a bent pipe transponder.. might be an interesting experiment and stimulate some kind of response from Fox-1C (Just an example, I know the up/down freqs are inverted for 1C, but it gets the idea across)......basically:  Drew's house------(UHF up)----->(UHF RX) Their bird, bent pipe (VHF TX)---> (VHF RX) Hurt Bird.

When 1E launches (VHF Up, UHF Down).....could make for some fancy fun.........relay the 1200 bps tlm via their bird......or make voice contacts back and forth between the pair of bent pipe transponders.....or maybe do both at the same time.........Depending on orbits and such, this could make tuning for Doppler fun with multiple hops and different bands in the mix.......sometimes you might have to tune UP on the downlink.

Idea 2:  How 'utilized' are the Amateur Satellite Service bands?
Different idea could be spectrum mapping.......depending on the type of SDR, if they can receive the full 3 MHz of 435-438 MHz band....do some FFT/averaging magic, store off FFT 'snapshots', and then later downlink the snapshots.  Idea would be to develop a 'heatmap' of the use of the 435-438 MHz band.  Doesn't have to be hyper-precise geolocation or anything that crazy to still to be useful......as long as they manage a reasonably accurate timestamp for when the FFT was taken (preferably in UTC, or at least something that can be mapped to UTC) they could figure out where the bird was from TLEs later.  If they happen to be flying a GPS, even better.  Global heatmap of the 435-438 MHz band might be good info for groups like IARU for coordination purposes.

Idea 3:  Simple software defined transponder
Do thing like the SDX from ARISSat-1 days.  Basically a 'plain old' bent pipe transponder, but with things like power normalization from uplink to downlink so everyone gets an equal share of downlink power (LEILA).  If a 'violator' exceeds uplink limits for too long, send them some CW on their equivalent downlink freq telling them to turn down the juice.  Another one I would love is FM up, SSB down.......would let me use my TH-F6A for QSOs (or any other HT that can TX FM, and receive all-mode).  Another mode under this category could be a basic APRS digipeater.  The novelty is not doing the basic things individually, it would be being able to change modes from one to the next to the next with the same software radio running different waveforms (one day they're making heatmaps, the next they are an APRS repeater, the next they are an FM repeater, the next they are an SSB transponder with power normalization, etc. etc. etc. ).

Good Stuff!

-Zach, KJ4QLP

-- 
Research Associate
Aerospace & Ocean Systems Lab
Ted & Karyn Hume Center for National Security & Technology
Virginia Polytechnic Institute & State University
Work Phone: 540-231-4174
Cell Phone: 540-808-6305

-----Original Message-----
From: AMSAT-BB <amsat-bb-bounces at amsat.org> On Behalf Of Ev Tupis via AMSAT-BB
Sent: Tuesday, October 29, 2019 6:13 PM
To: amsat-bb at amsat.org
Subject: Re: [amsat-bb] Secondary mission ideas

 How interesting!
In very general terms: QSO Robot
Ground stations TX to the satellite using CW or PSK31 (so multiple uplink signals can spread out through a 3 kHz uplink passband.
The satellite responds back on a single frequency.
This happens all the time on HF where DX stations listen from 14.300 to 14.310 while responding on a single frequency like 14.290.
Concept presented. Details can be worked out later.
By the way...the now concluded PropNET Project used this concept for a decade...quite successfully.

Cheers,Ev, W2EV

    On Tuesday, October 29, 2019, 2:04:08 PM EDT, Andrew Glasbrenner via AMSAT-BB <amsat-bb at amsat.org> wrote:  

 I just had a super call with a university program flying a mission using
SDRs. We talked about licensing and coordination issues, and discussed ideas
for a secondary two-way mission that they want to do. 

What would you like to see, repeater, transponder, BBS, digital voice,
digipeater? Downlink would be on 2m, and would probably be limited to
20-25khz wide. Other ideas? Something new and different? Let's have a
civilized discussion about what they could try, as they seem to be an eager
and capable bunch.

73, Drew KO4MA

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