Dual band HAM radio options, narrowing the choices

moose545

Member
Thanks Dave, point being that while the technology is there and "works" to send messages for example as all brochures explicitly advertise, it's not an easy thing to do AT ALL, and seems there's even more to it as you mentioned, such as needing to be in the FOV/orbit path or the satellite that will accept your uplink/sent message, and then relay it out. Is that accurate to say?
 

DaveInDenver

Expedition Leader
Satellite APRS works fine and the APRS side itself is no different than any other APRS station. The terminal and modem side is the same. The radio itself is the same, other than you use a different frequency.

But yes, it's not a constellation of vehicles to provide continuous coverage. There's a little bit more effort predicting when a satellite will come into view and where in the sky it'll pass over.

Then being in orbit means if the pass is well off the horizon you need to change the antenna orientation to face it. A vertical whip is usually completely deaf straight overhead, so you at least need to tip the antenna over or ideally use a Yagi to focus your signal and follow the satellite.

The satellite doesn't discriminate but stronger signals will prevail over weaker ones and things like Doppler shift can cause packet data corruption and just the number of hams sometimes trying to get a contact cause collisions. Also the pass might be 5 or 10 minutes so not a ton of time to get more than a message sent and acknowledged. Plus sitting there holding a conversation while others are trying to make contacts isn't courteous. Repeaters and spectrum are shared so you should definitely use it but be mindful of other hams, too.

I wouldn't call it hard but it does require the operator to do more than just push SOS and wait.

The professors and students at the Naval Academy are (or were anyway, the USAF isn't interested in letting USNA hams fly any more payloads) heavily into satellite APRS:


 
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Frdmskr

Adventurer
Don’t forget Hf APRS. There are a couple variations. It has a bigger foot print and will be heard in places VHF will not. You can do messages and such with it as well. You do need a license which gives you privileges on 30m though. In the US that is a General Class ticket.


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moose545

Member
Thanks for the replies, understand more of the inner workings of APRS, I don't think being out in desolate places overlanding and having a mobile Yagi antennae would be a practical answer to send a message with promised success in an emergency situation, nor tracking orbit paths to assure you were in the path or within sight, etc. I'm just getting into HAM and I have a pretty capable and complex radio, so I'll learn more about it as I go and see what's best and what I don't need to mess with much. Even functionality within EchoLink to send a text message is more involved than one of the other units which does require a subscription, but much easier ease of operation for me right now, that may change though. Back to seeing how to use my PC to talk on EchoLink from home! Thanks for the info guys~
 
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