As mentionned a couple of times on this list, you must have a minimum SNR per MODCOD. If your SNR is above, you have some Link Margin (LM):
Basic Service MODCOD 8psk 3/5 --> LM = SNR - 5.9 [dB]
HVS-1, HVS-2 MODCOD 16apsk 2/3 --> LM = SNR - 9.3 [dB]
The SR1 does nothing else when it calculates the link margin for BAS and HVS-1. I really don't understand why you Windows guys try the hell of snmp stuff to get these LM values from the SR1 if you alredy have the T1 SNR.
Just easily slightly adapt your sr1-snr.pl to make these calculations for you. Under GNU/Linux I do these calculations in the eLuna/RRDtool drawing routine only. This has all been explained shortly after I had an SR1 in 2014.