On 14/11/2021 21:15, Ernst Lobsiger via groups.io wrote:

Francis,

my point is, of course I cannot be 100% sure or prove it, that the SR1 people
used exactly those empirical constants to get their LM.
When I look at David's Ayecka #1 this evening comparing mean values I see SNR =
12.6 dB,  LM BAS = 6.7dB,  LM HVS-1 = 3.3dB.

But 12.6 - 5.9 = 6.7 and 12.6 - 9.3 = 3.3 as I stated above.

Cheers,
Ernst

Ernst,

Using the SNR also has the advantage of simplifying the MRTG, not needing to
run a Perl script. Almost!

For an HVS-1 or HVS-2 measurement the script below works well - sorry about the
wrap on the "Target" and "Options" lines.:

#----------------------------------------------------------------------------
# SR1 DVB-S2 receiver HVS link margin
#----------------------------------------------------------------------------

Target[SR1-hvs-link-margin]:
1.3.6.1.4.1.27928.101.1.1.4.4&1.3.6.1.4.1.27928.101.1.1.4.4:public@....194 -
93

MaxBytes1[SR1-hvs-link-margin]: 100
MaxBytes2[SR1-hvs-link-margin]: 100
Unscaled[SR1-hvs-link-margin]: dwmy
YTics[SR1-hvs-link-margin]: 5
YTicsFactor[SR1-hvs-link-margin]: 0.1
Factor[SR1-hvs-link-margin]: 0.1
Options[SR1-hvs-link-margin]: gauge, nopercent, growright, unknaszero,
nolegend, noi
ShortLegend[SR1-hvs-link-margin]: dB
YLegend[SR1-hvs-link-margin]: Link margin: dB
LegendO[SR1-hvs-link-margin]: High Volume Service:
Title[SR1-hvs-link-margin]: SR1 HVS Link Margin
PageTop[SR1-hvs-link-margin]: <h1>Ayecka SR1 - HVS Link Margin</h1>

#----------------------------------------------------------------------------

My MRTG knowledge isn't good enough to get it to display BAS link margin as one
value, and HVS link margin as another. For a single value the "Target" format
above is:

SNR-MIB-ID&SNR-MIB-ID:public@ip-address - 93

so both "input" and "output" in MRTG terms are SNR - 93. SNR is in units of
centibels.

What I don't know, and I can't discover is whether it's even possible is to get
both BAS and HVS link margins using a "Target" something like:

SNR-MIB-ID:public@ip-address - 59 & SNR-MIB-ID:public@ip-address - 93
or:
SNR-MIB-ID - 59 & SNR-MIB-ID - 93:public@ip-address

"Left as an exercise for the reader", perhaps?

Cheers,
David
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