[Skimmertalk] wlan0 interface loosing connection on RedPitaya as soon CW Skimmer Server starts

[Bob Wilson, N6TV]

On Wed, Apr 11, 2018 at 10:51 AM, <dd5xx at web.de> wrote:

> I have tried three different USB WiFi dongles (all 150 MB/s 802.11n) and I
> also installed the latest SD card image from Pavel Demin.
>

I assume you're saying that the theoretical speed of the 802.11n connection
is 150 megabits (not Bytes) per second.  Maybe you can find a tool for
Alpine Linux or your router that will display the actual data transfer
rate.  150 mbps theoretical max may still not be fast enough to pass the
data required for 8 bands x 192 kHz.  Try experimenting with 2 bands x 96
kHz and work your way up.  This is all set in CwSkimmer Server; nothing
needs to change on the Red Pitaya, though you may have to keep restarting
it CwSkimmer Server after clicking "Apply".

It may be worth trying the Ubuntu distribution for the Red Pitaya, instead
of Alpine Linux.  Perhaps the Ubuntu device drivers for your WiFi dongles
are more robust.  Or maybe not.


> I have done some troubleshooting:: eth0 has IP adress 192.168.1.100/24
> and wlan0 has 172.16.1.123/24.


Do things work any better if you unplug the Ethernet cable and bring eth0
down and tell the Red Pitaya to use wlan0 only?  Perhaps the SDR receiver
gets confused when it sees two network connections, though that seems less
likely than a pure speed issue.


> My LAN at home uses 172.16.1.0/24 network and my Windows PC I am
> currently writing this message hast IP address 172.16.1.99/24. Red Pitaya
> is autostarting sdr_receiver_hpsdr on each boot. On my Windows PC I start
> CW SkimSrv with CWSL_Tee. At the same time in parallel I have connected my
> notebook (IP address 192.168.1.44/24) to Red Pitaya and I have a SSH
> session open to Red Pitaya.


Instead of using an SSH connection, which forces network traffic onto both
paths, try connecting a USB cable from your PC to the second USB
connector.  Windows will recognize this as an FTDI serial port (even when
no power is connected to the Red Pitaya). You can configure PuTTY for a
SERIAL connection to the new virtual COM port at *115200 baud,N,8,1* .
Using a direct serial port console connection you can monitor network
traffic and issue commands directly without network conflicts or SSH
connections.


> On my Window PC I start CW SkimSrv and immediately the permanent pings to
> 172.16.1.123 fail and CW SkimSrv brings the error "SDR Failure. Too many
> receivers selected". On the open SSH on my notebook I run "ifconfig" but I
> see that wlan0 still is present and active. At the time I run "ifconfig
> wlan0 down" my Windows PC brings the CW Skim Srv application pop up that
> the process crashed (violation error 0xblabla). This is reproduceable and
> happens only when using WiFi, on LAN I have no issues and everything works
> as expected. It happens when I use "CWSL_Tee" or direct "RP-xxxx-30 v25"
> Receiver selected in SkimmerServer v1.6
>
> Anyone experiencing this and can provide a solution? Thanks to everyone in
> advance.
>

I'm not aware of anyone who has been able to make reliable WiFi connections
between the Red Pitaya and a Router while running CwSkimmer server at 8
bands x 192 kHz; it's just too much data for most WiFi dongles to handle.
Perhaps the Red Pitaya CPU gets overloaded with interrupts?

1 gigabit Ethernet direct to the PC or Gigabit switch is really the best
way to go.

If you're not satisfied with that answer, and you MUST use WiFi, I'm afraid
that even Pavel Demin may be unable to help you, as it's probably an OS
networking limitation, or a limitation of your WiFi router or the dongles.

The SDR receiver (or Alpine/Ubuntu) is very sensitive to even momentary
network delays or drop-outs, which is why it is best to wire the RP
directly to a PC (or via a dedicated gigabit switch), bypassing your
Internet Router entirely.  When the cable company decides to reboot my
Router in the middle of the night for "updates" or something, I can't
afford to have the Skimmer go down, but that's what happened when the Cable
box (a combo Router and switch) was between my Red Pitaya and my PC.
Putting nothing but a "dumb" Ethernet switch between the PC and the Red
Pitaya solved that issue quite well; it keeps on skimming even when the
Router is rebooting.

73,
Bob, N6TV