[Starlink] starlink at sea

[Jared Mauch]

I haven’t poked hard, but it does seem you can get it:

currentCellId current_cell_id

Seem to be in the GRPC proto dump from the dish.

https://github.com/sparky8512/starlink-grpc-tools/blob/main/extract_protoset.py

This should pull it out, if you want from my (stationary) dish I bet I can run something to pull/dump the info.

- jared

> On Jul 14, 2022, at 8:49 AM, Nitinder Mohan via Starlink <starlink at lists.bufferbloat.net> wrote:
> 
> Hi Mike,
> 
> Do you happen to have a tool that can extract the current uplink channel of Starlink and (more importantly) which staellite it is connected to at any given time? I wanted to track the handovers in Starlink and try to find its impact on network performance but cannot seem to get those values. 
> 
> Thanks and Regards
> 
> Nitinder Mohan
> Technical University Munich (TUM)
> https://www.nitindermohan.com/
> 
> From: Sebastian Moeller via Starlink <starlink at lists.bufferbloat.net>
> Reply: Sebastian Moeller <moeller0 at gmx.de>
> Date: 14. July 2022 at 14:35:16
> To: Mike Puchol <mike at starlink.sx>
> Cc: Dave Taht via Starlink <starlink at lists.bufferbloat.net>
> Subject:  Re: [Starlink] starlink at sea 
> 
>> Hi Mike.
>> 
>> Thanks a lot. This is intersting.
>> 
>> > On Jul 14, 2022, at 14:02, Mike Puchol <mike at starlink.sx> wrote:
>> > 
>> > The uplink is an OFDM signal with 128 subcarriers, looking at the signal in the time domain reveals a frame length corresponding to 14% (from memory, 1,1 us frame vs 6.7 us pause). I have two terminals 1 meter apart and they can each achieve 30 Mbps at the same time over the same uplink channel. I would expect the satellite to assign a particular set of slots to a terminal.
>> 
>> So assuming the 30 Mbps being gross rate and not measured goodput:
>> 
>> 30Mbps -> 30 / (1.1/(6.7+1.1)) = 212.73 Mb/s while actively sending, and 
>> 1000000µs/s / (6.7+1.1)µs = 128205.128205 slots/sec
>> (30 / (1.1/(6.7+1.1))) * 1000^2 / (1000000 / (6.7+1.1)) = 1659.27 bits/slot 1659.27/8 = 207.41 Bytes/slot
>> 
>> with 128 subcarriers that would be approximately an average 
>> 
>> 1659.27/128 = 12.96 or ~ 13 bit/subcarrier 
>> 
>> if all carriers are loaded equally (which is unlikely, I expect some re-arrangement ot bits between subcarriers to account for different levels of noise and what not).
>> 
>> 
>> > If there are any OFDM blind analysis experts in the room, shout!
>> 
>> Please do!
>> Regards
>> Sebastian
>> 
>> > 
>> > Best,
>> > 
>> > Mike
>> > On Jul 14, 2022, 13:33 +0200, Sebastian Moeller <moeller0 at gmx.de>, wrote:
>> >> Hi Mike,
>> >> 
>> >>> On Jul 14, 2022, at 13:15, Mike Puchol via Starlink <starlink at lists.bufferbloat.net> wrote:
>> >>> 
>> >>> On the multiple terminals, I have verified that the duty cycle of a consumer terminal is 14%, thus, you could have 7 terminals on a single uplink channel with some guard time.
>> >> 
>> >> Could you elaborate how that works.how the terminals will be interleaved in that situation?
>> >> 
>> >> Regards
>> >> Sebastian
>> >> 
>> >> 
>> >>> I have seen 30 Mbps up, so you’d be able to push 210 Mbps in uplink, or a spectral efficiency of about 3.4 bps/Hz.
>> >> 
>> 
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