[pskmail] Re: server on Rasp Pi or Beablebone Black

  • From: John Douyere <vk2eta@xxxxxxxxx>
  • To: Unname <pskmail@xxxxxxxxxxxxx>
  • Date: Fri, 29 Aug 2014 11:31:39 +1000

Hi Greg,

I can't remember saying it was not powerful enough, just that the THOR
modes are more demanding that most of the other modes.

If I remember well the discussion thread I was asking if the CPU load was
not too high on Raspberry PI as the OM could not decode PSKR modes. In the
end the issue was not with CPU load but a bug in the Fldigi PSKR code.

The OM also reported that THOR modes could be decoded.

Having just converted a few Fldigi modems into Android using not the Java
language but C++ *natively *I have some reasonable idea of the capability
of some of these ARM CPUs without the Java overhead.

For example a rather old HTC Desire phone can decode PSKR, THOR, OLIVIA,
MFSK and even MT63 2000L without problems. The CPU load does not exceed 50%
which leaves enough room for other processes.

Looking at the results of benchmarks like the Whetstone Native (not Java)
benchmark results for Raspberry PI on the net I find values of 95 MFLOPS at
700Mhz CPU clock (the default I understand) and 134 MFLOPS at 1000Mhz clock
speed (over-clocked).

Compare this to the results of 120 MFLOPS for my HTC desire mentioned above
and you can see that it is very comparable. So in my opinion it should work
on a Raspberry PI, ASSUMING that there no significant extra overheads
introduced by the GUI side of Fldigi + O/S.

I don't know what Per has done to make it work in terms of configuration
but I would suggest looking at the following:

- Overclock the Raspberry PI to 800-900MHz (Do some research here as it
seems to be the maximum acceptable long term continuous running overclock
limit).

- In Fldigi:

1. Set the slow CPU option ON.

2. IN THOR modem disable filtering, soft-symbol and soft-bit decoding.

3. In Audio / Settings I would choose either Linear interpolator or Fastest
Sinc interpolator.

- Finally and it can be important on some devices, run Fldigi minimized.
This reduces the GUI processing quite significantly regardless of the
settings of the waterfall.

Maybe Per can detail his configuration to make it work on the Raspberry PI.

I believe the Banana PI with it dual core 1GHz ARM-V7 architecture
(including hardware floating point unit) should provide a much lower CPU
load when running Fldigi and a Pskmail server.

Hope this helps,

73, John (VK2ETA)




On Thu, Aug 28, 2014 at 2:01 AM, Greg <kb1ncj@xxxxxxxxx> wrote:

> Greetings Group,
>
> I see people mention they are setting up servers with these new micro
> devices.. I thought I remember when I asked about this maybe a year ago,
> John (VK) I think said that they were not powerful enough especially with
> the THOR modes... Still true? I would switch my server out just to save on
> electric use.
>
> Also my server was on boot stuck for a few weeks but back on now..
>
> Greg
> KB1NCJ
>
>

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