Someone I work with was thinking of writing a virus social collapse related short story, of course shortwave radio and satellite are perfect ways to introduce a one-way data channel which can inject a wider world narrative from very far away but cant hear your screams for help. I suggested Othernet as something more fun and exotic than a simple SW radio.
@Syed has mentioned that the Othernet lab has the hardware to transmit a test feed directly to SES-2 for the North American footprint though usually lets SES do the uplink. I am curious (preserving the sat-corp security through obscurity etc) how much support from SES is needed for Othernet to self-feed the signal? If a zombie-esque cinematic society collapse were to happen what access would Othernet have to the satellite without SES’s support.
Is there a partner in Europe who could direct feed Othernet to Astra 3B were the SES uplink to go down?
What hardware is involved in a test uplink, how portable is it? Power requirements? Can it run from a small portable generator or an inverter run from a automobile electrical system?
Off topic, interesting project I am also playing with.
@biketool There is absolutely no reason we can’t host the uplink in any arbitrary location. It’s simply easier and more reliable to uplink through the SES teleport (redundant power and data, not to mention remote hands when necessary). No support is technically required from SES to bring up a carrier, though contractually we do need to coordinate with the payload management center so they can confirm a clean carrier at the correct power level. Uplinking only requires a VSAT; any cheap terminal will do.
We don’t have any partners that could uplink for us. There is no technical barrier to this. It’s just has not been arranged.
As mentioned above, a simple VSAT will do. Something with a 76-cm or even 60-cm dish would do. The smaller that dish the more powerful the BUC needs to be, but I’m pretty sure that a 4W BUC would be plenty for our 1 MHz of capacity.
A portable power system that can provides 40W continuous is all that is needed. A generic car battery provides maybe 1200 watt-hours (5 amps for 20 hours at 12 volts), but we aren’t factoring in losses. Let’s just assume (supported by some quick googling) that a standard car battery can provide about 4 hours of transmission while staying above 50% discharge.
Your friend should research would the hams are doing with QO-100.
Very cool @Syed, 4W is some serious QRP to GEO!
Obviously for day to day using the SES gateway makes sense, like hosting a website form a data center vs some old linux box in your closet over a DSL line; until zombie day arrives.
Anyways in fiction why cant we have a ham GEO over NA?
I haven’t had time to sit down and make a portable SSB/CW transceiver to use the bent pipe transponder birds, especially unfortunate when I was working in the ME where I could hit QO-100, but don’t feel like buying a dedicated SSB radio with kludged up/down transverters when I should be making my own gear. Maybe a SDR and transverters/amps in a nice case, someday I will go back to researching options.
You can easily have a ham GEO over NA. Just pony up the cash.
Don’t be poor, got it!
What band do you uplink on L-band, Ka?
@Syed, I think this has been asked before, SES runs dumb analog bent pipe transponders and controls interference by policing the stations uplinking? I imagine like the modern US DOD UHF com-sats they can selectively can black out as wide a band as they like to kill off pirates even if they cant lock them out. The older sats like FLTSAT and maybe UFO have to deal with the Brazillian and Portugese sat-hackers running commercial VHF(~160mhz) with frequency doublers into amps to get transatlantic 300mhz UHF mil-band CB chat radio.
I always understood that the big radio telescope looking antennas(>30m dish) were to give a great signal so the satellite could dial down the gain for that bit of the transponder and keep unwanted signals out.
The L-band uplink changes based on the LO of the block upconverter (BUC).
SES is not the only operator running dumb bent pipes. The vast majority of commercial (and non-commercial) communications are bent pipes. They are very flexible and simple, which is what you want on an expensive, inaccessible asset. The WorldSpace satellites were amazingly advanced for their time, with digital transponder. But it used some arcane, bespoke modulation which is not supported by any RF modems, so the processed beams are just dormant. Bent pipes are great because what you uplink is exactly what you downlink. You can do all of your fancy business on the ground. The satellites needs to only stay powered and in its little box, far far away.
I’m not sure what security measures the commercial operators have in place.
Just to clarify I love the absolute flexibility of a dumb bent pipe(cant revert to analog over a digipeater/orbital router, can do almost any digital over analog with a good SNR) even if the gain curve can be adjusted across the transponder. I am just surprised that it is still the standard from a security standpoint. Do you have to be on the phone with SES and adjust the satellite gain when using the VSAT?
As for security there are so few people in the world with personal access to the knowledge and equipment, especially for big wide band HD+ signals coming from big dish farms.
If you could post a video of waterfall between say a satellite radio, tv, and Othernet signal it would be a cool way to illustrate to people how narrow the signal is and how we can get by on such small power budgets. What ratio of the data in the othernet LoRa signal is forward error correction vs usable data signal?
Yes, but the satellite gain is fixed. It’s the uplink power we adjust, based on SES monitoring.