Re: Tellicast client version 2.14.4 for Linux


David J Taylor GM8ARV 🏴󠁧󠁢󠁳󠁣󠁴󠁿 🇪🇺
 

Hi All,

As promised I did some "beta testing" of TC client 2.14.4.
David mentionned that documentation of the new parameters
under Windows is missing. Here some answers to his questions.

I found not much new except for the EUMETSAT distributed
channel ini files do not work as expected under GNU/Linux.
"receive_buffer_size=8000000" seems to be a no go :-(.

Attached my findings so far ...

Cheers,
Ernst
==========================================

Ernst,

Many thanks for that.

As all the other parameters are specified in bytes, I expect that the buffer size is as well. The pedants would be arguing between MB and MiB!

There was a note in the current TD15 that the default buffer size - if not specified - was 4000000. That note also suggests it's since 2.14.4 (meaning 2.14.4 and later, or post 2.1.14, perhaps a subtly different meaning in the German?).

https://www.eumetsat.int/website/wcm/idc/idcplg?IdcService=GET_FILE&dDocName=PDF_TD15_EUMETCAST&RevisionSelectionMethod=LatestReleased&Rendition=Web

I found that the 2.14.4 program worked as expected both without a buffer size begin specified (i.e. just replacing the .exe and the licence.ini file in Windows systems), and with the buffer as 8000000 as in the EUMETCast example channels file.

I'm also using a RAMdisk for temp and received files on some systems, a RAMdisk for temp on others, and no RAMdisk at all on other systems (one HVS-1 and one HVS-2). I'm trying to see whether there are any differences although the measurements are made more difficult here partially because of the slight skew error, and partially because of the low signal here (with the weather conditions making things worse).

It's too early to tell whether there's any difference. Whilst I agree that having the temp.data RAMdisk helps, it's still possible that that using a bigger buffer in the TelliCast would reduce the number of calls to the OS for disk I/O operations, so there might be a benefit.

But most of my problems with HVS-2 are lost TelliCast packets, so if they're not coming in over the network there's not much you can do about that, unless in the exceptional case of the network interface (or virtual network in the TBS PCIe case) not having enough buffering. As we're using gigabit interfaces and network cards on the Ayecka SR1 that's capable of speeds some 12 times in excess of what's needed. Interestingly, the SR1 can occasionally produce zero packet loss on the PC without a RAMdisk at all, while the TBS/temp/files/RAMdisk system always has missed & recovered packets.

Fun, this TelliCast, isn't it!

Cheers,
David
--
SatSignal Software - Quality software written to your requirements
Web: http://www.satsignal.eu
Email: david-taylor@...
Twitter: @gm8arv

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