[hobonation]

Iridium terminals can be very power-efficient. Consumer ones are the size of a deck of cards and can last for days.

[Scoundreller]

I wonder how much of the power-efficiency is due to being much slower.

Don’t need to blast and beam-steer if you can deal with poor SNR by taking your time to differentiate the 0s and 1s?

Which is more power efficient per megabyte?

(But I get it: sometimes a few bits is all you need)

[lxgr]

All of it. You can't really get around physics.

Iridium has historically targeted low-power, omnidirectional terminals (antennas can be larger at lower frequencies without requiring steering than at higher frequencies).

They recently had some forays into steered, high-bandwidth antennas with their Certus line and their second-generation satellites that now allow native packet switching (the first gen was circuit-switched at 2.4 kbps only), but that brings you into the bandwidth-limited regime, and is honestly just a waste of scarce L-band spectrum and much better served by all the Ku- and Ka-band LEO competitors.

It's going to be interesting to see if Rocketlab start also serving that market, like some of their main competitors already are.

[labcomputer]

> (antennas can be larger at lower frequencies without requiring steering than at higher frequencies).

No.

1. Iridium uses frequencies fairly close to GPS (~1.6GHz).

2. Iridium uses cylindrically-polarized transmissions (like GPS), which enable compact omnidirectional helical antennas

> They recently had some forays into steered, high-bandwidth antennas with their Certus line and their second-generation satellites that now allow native packet switching (the first gen was circuit-switched at 2.4 kbps only), but that brings you into the bandwidth-limited regime,

This is AI slop?

No, the point of using an electrically-steered beam antenna is that it improves SNR, so that you are not bandwidth limited.

[lxgr]

> 1. Iridium uses frequencies fairly close to GPS (~1.6GHz). 2. Iridium uses cylindrically-polarized transmissions (like GPS), which enable compact omnidirectional helical antennas

Which part of my argument is this an objection to?

Are you saying that using circular polarization, the same would be possible in the Ku or even Ka bands? Because that’s definitely not the case due to the different aperture/gain tradeoff vs. L-band, and that’s my point.

> This is AI slop?

Did I say anything incorrect there or do you just not like my writing?

> No, the point of using an electrically-steered beam antenna is that it improves SNR, so that you are not bandwidth limited.

Sure, but my point was: At low frequencies, you can steer to become more efficient per bit, but at high frequencies you almost have to, as you’re sending energy in suboptimal directions otherwise. And then if you’re already steering, why not use a less-scarce band?