No signal after wake up from standby

[tikimune]

Hi guys,

I can't watch TV channels when computer wakes up from standby. Media center tells me, there's no signal or weak signal. After reboot all works well, until I use standby again. Strange think is, that all DVB-S2 channels seem to work even after standby. Only common DVB-S channels are affected.

[tikimune]

It seems that after resuming from standby, my TBS921 can only receive channels from lowband. I've testet several horizontal and vertical lowband channel with success. Strange thing even though I can watch these channels, mediacenter shows 0% quality.

[cody]

hi and thanks for reporting this - as you can see there are numbers of issues with TBS 6921 drivers reported to the forum, i'm in process of summarizing them all and start investigating them, because if not all at least some of them will be related to each other. so, i'm guessing the problem you're reporting is related to 22 kHz tone control and initialization after the wake of from standby. i'm sure all those driver issues will be resolved with the future driver updates - it's always like that with newer products - there are initially a lot of troubles with the drivers found by the customers that are later resolved in the next driver versions. so, i appreciate and thank everyone, who is reporting the issues to us, it's vital for improving our products.

[Derrick]

Dunno whether there's a relationship with what I have observed concerning the blind scan tool. Users have made complaints about missing 22KHz. At least for the new version 2.0.1.2 of the TBS8921 BlindScan.exe this is not really true. The tone is present but the tone amplitude is less than half (-8dB) of the normal 22KHz signal. Maybe this is not enough for band switching. I can't test this cos I need a working diseqc which is not implemented in the tool for the time being..

[cody]

The tone is present but the tone amplitude is less than half (-8dB) of the normal 22KHz signal. Maybe this is not enough for band switching.

tone amplitude can be adjust in the driver, but is there specification what is considered "normal", i.e. you say it's at the moment -8dB less the "normal"? thanks.

[Derrick]

you say it's at the moment -8dB less the "normal"?

yep, 8dB below "normal".

but is there specification what is considered "normal"?

There are recommendations for diseqc (Eutelsat, BUS FUNCTIONAL SPECIFICATION, VERSION 4.2)

The nominal 22 kHz signalling amplitude is 650 mV (±250 mV) peak-peak.
To accommodate tolerances and voltage drop in the cable, the detector should
respond to amplitudes down to approximately 300 mV (±100 mV). The
maximum recommended amplitude to be applied to the bus is 1 volt peak to
peak.
Designers of receivers and all peripherals (i.e. “Masters” and “Slaves”)
should strive to avoid injecting “noise” or spurious signals onto the Bus.
However, it is recognised that some disturbance may occur on a cable which
carries both power and data signals. Therefore, it is recommended that the
DiSEqC tone reception interface circuits should not lead to detection of
signals (at any frequency) having an amplitude of less than 100 mV peak to
peak (either cyclical or “spikes”).

[cody]

thanks for the information, i'm making driver with signal statistics as we discussed here:

https://shop.tbsdtv.com/forum/viewtopic.php?f=27&t=211&start=10#p1280

in order to debug the "frequency offset" problem for low-symbol-rate. so, i'm adding adjusting the 22kHz tone amplitude as part of this driver, i.e. i will changes the settings in that debug driver after we finished with collecting info for the "frequency offset" problem. i hope we will be able to reach same stability of the driver as we did with our older products like 6980, which required even to completely re-write the initial drivers from scratch with new architecture after the initial one proved to be not stable in practice by the customers.

[Derrick]

..just for clarification: "normal" means the level that is applied by the TBS driver for band switching (continuous tone). The amplitude -8dB applies for the blind scan tool.

[lujo]

I am using TBS 6921 on Windows Home Server (based on server 2003) with 2.0.0.4 driver.
Software that I use is TVSource 3.2.1 from DVBLogic.

I have tested this with Stand By (S3) and also with Hibernate but TBS 6921 is not working after Stand By or Hibernate.

Can we expect that this will be fixes soon because this is for me very important, my Windows Home Server is every time going into Stand By (Lights-Out) when my computers are not used (off)?

Will logfile made with Dbgview.exe help you to find solution for this problem?

[cody]

@lujo

yes, you can be absolutely sure all resume-from-sleep issue will be resolved with driver update. there is no need to collect any debug data about it, because we already know where is the problem and also we have a lot of experience with similar issues which we fixed many months ago for some of our older products.