Recording more than one channel at the same time, some channels doesn't work, why?

[danchoif2]

That's nice, right!
We can use multiple usb dvb-t card + an USB hub + an antenna hub, then put them in a box , so we have as much as we want tuners work at the same time with cheaper price than one quad-tuners.
If we buy on ebay, I can buy an usb dvb-t card with only ~12 euro

[Reddwarf]

Also Reddwarf what would be your advice about having multiple USB capture cards? Would USB Bus take it?

Steeb

USB capturecards usually draw their power from the usb-port on the computer, which is very limited so I would be very careful not to overload the machines usb-controller. Apart friom that it should have no problem handling two tuners.

[pBS]

each usb port should provide more than 1 amp of power, way more than needed and plugging more in won't use any more, each has it's own independent power supply..
but the usb bus however actually uses cpu to do some of it's work, the bus can get saturated..

i wouldn't use a hub if at all possible...or definitely make it a powered hub [w/it's own power supply]
[hubs combine usb devices on 1 port so they have to divide bandwidth=really bad idea]

oh and be carefull to select different usb devices or make sure more than one of same kind can be used together...
[driver issues if not written properly for more than one at a time]
not a problem if they all use different drivers

[Reddwarf]

each usb port should provide more than 1 amp of power, way more than needed and plugging more in won't use any more, each has it's own independent power supply..
but the usb bus however actually uses cpu to do some of it's work, the bus can get saturated..

i wouldn't use a hub if at all possible...or definitely make it a powered hub [w/it's own power supply]
[hubs combine usb devices on 1 port so they have to divide bandwidth=really bad idea]

oh and be carefull to select different usb devices or make sure more than one of same kind can be used together...
[driver issues if not written properly for more than one at a time]
not a problem if they all use different drivers

The specification states that a usb-unit (USB 2.0) should draw no more than 100mA (0.1A), and that a usb-host should be able to supply up to 5 units at the same time, which gives us 0.5A (500 mA). This was extended to 900mA for USB 3.0. That is not 1 A in any case, and a lot of motherboards does not deliver more that 200mA before the voltage drops below spec.

So in any case is is a good idea to use a powered hub, but do not attach too many usb-tuners to the same usb-interface as they have to share the bandwith, and with HD-tuners this can become an issue.