On Sun, Jan 22, 2023 at 8:54 PM Tom Beecher <beecher@beecher.cc> wrote:
Yes re: Iridium. Contrary to what the Chief Huckster may say, inter-sat comms are not some revolutionary thing that he invented.
1990s Iridium was a modified version of GSM/ATM with the packetization and routing that implies. I don't know the current constellation's architecture but I'd be shocked if they had reverted to a bent pipe architecture. For those not in the know, a "bent pipe" communications satellite is one which accepts a radio signal in one frequency and does an analog transform to another frequency before sending it back out. Up from the ground station on one frequency, transform, down to the customer. Up from the customer on one frequency, transform, down to the ground station on another. The nice thing about a bent pipe is that you can upgrade the service equipment to higher speeds without changing the satellite. The satellite doesn't care. It doesn't recognize the concept of bits or packets. The bad thing is that it's straight up and down, so when the satellite isn't both in range of the customer and a ground station, you can't use it. The vast majority of satellite architectures are bent pipe. Regards, Bill Herrin -- For hire. https://bill.herrin.us/resume/