[Starlink] starlink at sea

[Nitinder Mohan]

Hi Jared,

Turns out that SpaceX has deprecated the API calls to get satelliteID and cellID over gRPC so that information is no longer available. See https://github.com/danopstech/starlink/issues/27

Too bad since those would have been quite useful to understand performance trends.

Thanks and Regards

Nitinder Mohan
Technical University Munich (TUM)
https://www.nitindermohan.com/

From: Nitinder Mohan <mohan at in.tum.de>
Reply: Nitinder Mohan <mohan at in.tum.de>
Date: 14. July 2022 at 15:05:42
To: Jared Mauch <jared at puck.nether.net>
Cc: Dave Taht via Starlink <starlink at lists.bufferbloat.net>, Mike Puchol <mike at starlink.sx>
Subject:  Re: [Starlink] starlink at sea  

Hi Jared,

Thanks much for the pointer. This seems promising!

We have a stationary dish available locally so we can try pulling information at our end. 

Thanks and Regards

Nitinder Mohan
Technical University Munich (TUM)
https://www.nitindermohan.com/

From: Jared Mauch <jared at puck.nether.net>
Reply: Jared Mauch <jared at puck.nether.net>
Date: 14. July 2022 at 14:57:25
To: Nitinder Mohan <mohan at in.tum.de>
Cc: Mike Puchol <mike at starlink.sx>, Dave Taht via Starlink <starlink at lists.bufferbloat.net>
Subject:  Re: [Starlink] starlink at sea  

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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>> Starlink at lists.bufferbloat.net  
>> https://lists.bufferbloat.net/listinfo/starlink  
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