Measuring Link Margin with a Linux TBS 6903X system - how?


David J Taylor GM8ARV 🏴󠁧󠁢󠁳󠁣󠁴󠁿 🇪🇺
 

When using a TBS6903X on a Linux system, how do you go about measuring SNR - or
more precisely - link margin?

I know that CrazyCat - has kindly provided a program for Windows called
SignalEx.exe, which has a choice of "snr", "ber" and "rflevel" as parameters
and returns an integer representing 10 times the dB value.

Is these anything similar for Linux? MRTG is vary useful for monitoring both
short-term and long-term variations.

Thanks,
David
--
SatSignal Software - Quality software for you
Web: https://www.satsignal.eu
Email: david-taylor@blueyonder.co.uk
Twitter: @gm8arv


Ernst Lobsiger
 

David,

you can get all this info from femon in a bash script. I basically use these lines in eLuna to update my RRDs every 5 minutes:

#!/bin/bash
# This prints out signal strength in (integer) dBm when using TBS Open Sorce drivers (-a0=adapter 0)
upd=0x`femon -a0 -c1 2>/dev/null | tail -n1 | cut -d'|' -f2 | cut -d' ' -f3`
upd=`echo $upd | awk '{print ($1/656.0-100.0) }'`
echo $upd


#!/bin/bash
# This prints out C/N (signal/noise) in dB when using TBS Open Source drivers (-a0=adapter 0)
upd=0x`femon -a0 -c1 2>/dev/null | tail -n1 | cut -d'|' -f3 | cut -d' ' -f3`
upd=`echo $upd | awk '{print ( $1/3280.0 ) }'`
echo $upd


-a0 = adapter 0 (usually T1, BAS + HVS-1)
-a1 = adapter 1 (usually T2, HVS-2)

Link margin as discussed a couple of times on MSG-1 is:
lm8psk=snr - 5.9
lm16apsk=snr - 9.3
I do these calculations when plotting the timeline in eLuna.
This could also be done with awk in the bash script above.

I have no script for ber but this is easy to setup in a similar way.

Hope this helps,
Ernst


Ernst Lobsiger
 

David,

femon is part of dvb-apps. There is an adapted femon-s2 from CrazyCat that comes with the OS drivers. This version also outputs the temperature of the demodulator chip for TBS-6909X and TBS-6903X.
To use these apps you must be root. Are you setting up a GNU/Linux system with a TBS-6903X? This card also works as a single cable T1 + T2 TelliCast receiver. AFAIK the Windows driver isn't TC ready.

Cheers,
Ernst


David J Taylor GM8ARV 🏴󠁧󠁢󠁳󠁣󠁴󠁿 🇪🇺
 

On 29/09/2021 18:53, Ernst Lobsiger via groups.io wrote:
David,

femon is part of dvb-apps. There is an adapted femon-s2 from CrazyCat that
comes with the OS drivers. This version also outputs the temperature of the
demodulator chip for TBS-6909X and TBS-6903X.
To use these apps you must be root. Are you setting up a GNU/Linux system with
a TBS-6903X? This card also works as a single cable T1 + T2 TelliCast receiver.
AFAIK the Windows driver isn't TC ready.

Cheers,
Ernst
Thanks for the info, Ernst.

No, all my Linux systems are Raspberry Pi (except one) - so "I'm asking for a
friend!".

David
--
SatSignal Software - Quality software for you
Web: https://www.satsignal.eu
Email: david-taylor@blueyonder.co.uk
Twitter: @gm8arv