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muccc / iridium-toolkit

A set of tools to parse Iridium frames
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Questions about the beam handover of Iridium satellites #119

Closed xyj8 closed 4 months ago

xyj8 commented 5 months ago

Hello, I saw in your toolbox that you can calculate the transmitting beam of an Iridium signal. Have you ever compiled specific rules for the 48 beam changes of Iridium.

Sec42 commented 5 months ago

Hi,

we do not calculate any beams. We do print the beam number transmitted by the satellite in IRA and IBC packets.

The rule is that a satellite cycles through all it's enabled spot beams in 4.8 seconds, so if you check the receive timestamps of IRA packets from a single satellite modulo 4800ms you should be able to identify the order in which the beams are transmitted.

xyj8 commented 4 months ago

Hello, thank you for your response. I would like to know why the period is 4.8 seconds. The literature I have reviewed states that the period is 4.32 seconds.

Sec42 commented 4 months ago

You are correct, it was a typo. 48 * 90 ms = 4320ms