Lost packets when both tuners are in use

[JessMG]

Hi everybody. I bought this card about a month ago, but I have been having some problems with it. At first I thought there could be some kind of interference that affected de signal that goes through the cable from the LNB to the TBS6983 (Maybe a very strong Wi-Fi or PLC device), but by testing I saw that when both tuners are being used (Transedit + DVBViewer [or any other program like EBSpro]) I start having lost packets that increase little by little over time, causing image problems. I have also seen a sudden increase in missing packets when one of the cards is tuning to another channel (a spike of maybe 30-70 lost packets, is very random). It doesn't happen whe only one of the tuners is working.

I've tested everythink I thought that could be messing with my card: power supply, PCI slot, RAM, CPU... all appears to be working properly.

My PC specs are as follows:
Windows 8.1 Pro
CPU: AMD FX-8150
Motherboard: Gigabyte 990FXA-UD5
16 GB RAM
GPU: ASUS GTX 760 MARS
PSU: Corsair 750W

Thx for your help!

[Euro1080]

Using Windows 7 here, and I am seeing similar symptoms with my new TBS 6983.

When only a single tuner is active, can you stay tuned to a signal for hours without seeing any continuity errors? I cannot... I still get some errors when using only a single tuner over the course of several hours, although they are fewer and less frequent than when both tuners are in use.

In my case, the continuity errors always show up in groups of 16 at a time, distributed among the various PIDs of the transport stream in an uneven fashion. Usually, one random PID will get 15 continuity errors at a time, while some other random PID will get a single continuity error. Then several minutes, perhaps even an hour, will go by without errors, until the process repeats itself: an additional 16 continuity errors show up simultaneously, distributed among the PIDs in a similar manner.

[steven]

Hi All

Can you tell us that which transponder both tuner are using? DVB-S or DVB-S2? normal signal or ACM/VCM?

Thanks

Kind Regards

steven

[Euro1080]

Can you tell us that which transponder both tuner are using? DVB-S or DVB-S2? normal signal or ACM/VCM?

Hi Steven,

I am seeing this behavior on any DVB-S or DVB-S2 signal. The coding mode is regular CCM.

After testing an even wider variety of scenarios, I have noticed that when a single tuner is active, I don't get any continuity errors as long as the total data rate of the whole transport stream stays roughly under 40 Mbps.

When both tuners are active, I don't get continuity errors only if the total data rate of both transport streams stays under that same 40 Mbps threshold. For example, 20 Mbps on tuner A and 20 Mbps on tuner B is perfectly fine: there are no continuity errors across either tuner. But 30+ Mbps on tuner A and 30+ Mbps on tuner B results in random continuity errors across both tuners.

This ~40 Mbps threshold above which the errors start to crop up is abnormally low, considering that your average mux nowadays is around 60 Mbps. Any old DVB card can easily handle that. So I am beginning to suspect I may have a faulty 6983.

[DVB]

Looks like confirmed here.

After some time (with only tuner A in use) 6983 is starting to gain missing packages. Always 16 random packets at a time, after some time there are 32 missing, 48 missing etc.



Higher bitrate = packets are missed faster. With ~70 Mbit/s - 448 packets missing after ~5 minutes



Windows 7 x64 + 6983 with latest driver. Also Gigabyte mainboard like @JessMG (Gigabyte P55-USB3)

@Euro1080 - do You have Gigabyte mainboard?

[JessMG]

Hi Euro1080, I usually get no lost packets while only one of the tuners is in use. I will test again and I'll tell you my results.

It seems I am not the only one having this problem, it is exactly as you and DVB described.

[Euro1080]

Thanks for the confirmations. At least now we know that we're dealing with a more widespread issue.

I have a Gigabyte motherboard as well. I can try installing the card in a different system with an Asus motherboard over the weekend, and then report back.

Either way, the next step is to get TBS's attention, since they're the only ones who can help us at this point. Perhaps we should all send our reports to their support email address?

[JessMG]

Hi Euro1080, I've already wrote to the support address, but after a reply from them asking about which PC chassis I use (Cooler Master CM-690II ATX, I think they were thinking of a problem with system temperatures, which are fine), I replied back but it has been two weeks since then with no answer.

I have been trying with just one tuner but in this case no packets are lost. If you could check again it would be very helpful, sometimes one of the tuners gets "stuck" by a system process (DVB viewer, Transedit or other capture software) and this could mix the results.

Don't know if this could be a motherboard-related problem beacuse chipsets (which manage PCI-CPU-HDD connections) are different between models (specially between Intel-AMD motherboards). Maybe something in the drivers or BIOS?

Another problem I am having is when I blindscan a transponder with EBSpro, sometimes the signal from the other tuner drops completely, and I only can get it back if I tune the transponder again. Don't know if this is normal behaviour.

Thank you both. I wish we could get an official answer from TBS (not an inexpensive card!).

[JessMG]

Well, as DVB reported, packet loss is also present while only one tuner is in use on high bitrate transponders. Just now I was recording a ~45Mbps BBC feed when suddenly the image stuttered.



If only anyone at TBS could help us (at least say SOMETHING)... This is getting really annoying.

[intracube]

Hi, was there any update to this?

I've just bought a 6983 but haven't installed the drivers yet. This has got me a bit worried as I've also got a Gigabyte motherboard.