Charlie,

welcome to MSG-1. You may have noted that most users are on Windows 10 or even 11. It's therefore a great pleasure for me to welcome another member of these few geeks that use GNU/Linux. I must admit that I have never used a DD card and IIRC you are the first person I heard of that tries to use these DVB-S2 receivers for EUMETCast. Your description of the system is full of brave decisions. This ultra small HP PC probably has no room for a big 3.5'' HD. That's why your filesystem is on a NAS via iSCSI (network) access. I wouldn't dare to do something like this but given the fact that the TelliCast client can even do (undocumented) similar things with FTP it might work just fine. But your current important problem is rather the DD frontend. As far as the dish is concerned I think it's pointed well especially given the fact that this TRIAX has a terrible elevation mount. That said a 1.2m dish would certainly be a much better choice but let's go with the TRIAX for now. An SNR=11.1 dB *should* allow for acceptable HVS-1 reception to begin with.

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I am aware most on the group are either using the TBS cards or Ayecka routers, but trying to get this going on a budget and a card that has the feature support at a fair amount less was too tempting, considering it uses most of the same hardware as the TBS 6903.
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If we have learnt something in the past then that hardware is 50% and the rest is drivers (or maybe firmware in the case of the SR1). I had the same HW on the TBS-6925 card as in the Ayecka SR1 in 2014. But I went through months of frustration before I finally got the first working EUMETCast DVB-S2 VCM PCIe card receiver on the planet under GNU/Linux.

https://groups.io/g/MSG-1/message/18219

The single BIT I set in a STV0900 register puts the FIFO in minimum lattency mode that is necessary for the special VCM Basic/HVS-1 signal. It later came as module parameter issy=0 (Konstantin) and finally ts_nosync=1 (CrazyCat) for the TBS distributed stv090x module. The TBS stv091x driver module used for the highly recommended TBS-6903 recognizes the EUMETCast signal and has an automatic FIFO setting built in (see code attached below). The same kind of code was part of a TBS-6909X driver module until recently. The latest version has again a module parameter that must be set ts_nosync=1. This can easily be done in /etc/modprobe.d as you probably know. I faintly remember that the DD drivers or part of those (ddbridge?) have not been open source in the past and made it hard to do your own stuff with STV registers or bridge DMA buffers. No idea what the current situation is. Do you download your drivers from some github repo and compile the source on your PC? Anyway my first advice is to get a list of modules ("lsmod") that are loaded for your DD frontend. Then (as root) make a "modinfo" for these DD driver modules and see what module parameter they have. You can also ask DD whether they are aware of the special FIFO setting for EUMETCast.


CrazyCat's trick for EUMETCast reception in TBS distributed stv091x.c (automatic minimum lattency setting)

...
                /* Check MATYPE flags*/
                read_reg(state, RSTV0910_P2_MATSTR1 + state->regoff, &tmp);
                read_reg(state, RSTV0910_P2_TSSTATEM + state->regoff, &reg);
                if ( tmp & 0x18 )
                        reg &= ~1;
                else
                        reg |= 1; /* Disable TS FIFO sync if ACM without ISSYI */
                write_reg(state, RSTV0910_P2_TSSTATEM + state->regoff, reg);
                /*pr_info("stv0910: %d TSSTATEM=0x%02x\n", state->regoff, reg);*/
                read_reg(state, RSTV0910_P2_TSSYNC + state->regoff, &reg);
                if ( tmp & 0x18 )
                        reg &= ~0x18;
                else
                {
                        reg &= ~0x18;
                        reg |= 0x10;
                }
                write_reg(state, RSTV0910_P2_TSSYNC + state->regoff, reg);
                /*pr_info("stv0910: %d TSSYNC=0x%02x\n", state->regoff, reg);*/

...



Cheers,
Ernst