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Min. (wireless) network connection speed
http://forum.linhes.org/viewtopic.php?f=2&t=4494		 Page 1 of 1
Author:  benotto [ Mon May 09, 2005 7:33 am ]
Post subject:  Min. (wireless) network connection speed
I have a working mythtv station (backend and frontend), connected to a adsl modem/router/wireless A.P. 802.1b/g.
I also have a notebook I use in different rooms, separated by at least one wall. Due to the low signal level, in order to have a stable connection, I have to switch to 11b at 11mbps (enough for internet anyway). I have not tried (I don't know how) to benchmark network speed, but I seem to be able to download from the internet at more that 220kb/s (not bad for a 2Mbps Adsl).
Nevertheless, this seems not enough for Mythtv, where real time tv is unusable and even xvid playing sometimes has difficulties.

Backend (XP1900+) has a AVERTV DVB-T 771 and is connected to the AP with 100Mbps ethenet (with knoppmyth 5A15.1).

The notebook (P4 2.8) runs Mdk 10.1 (kernel 2.6.10mm) with Thac's 0.18 Mythtv RPM; the netcard is a PCMCIA rt2500 with the open source (beta) driver. I sometimes have trouble starting the network, but usually after it has started it works properly.

Question is: what is the minimum requirement for connection speed between frontend and backend?
Anyone managed to run it on wireless network? At what speed?
Anyone tried network alternatives? (e.g. powerline, etc).

I think network capacity is my problem because if I connect a regular 100mbps cable to the router/AP real time TV works.

Ciao
Luca
Author:  Xsecrets [ Mon May 09, 2005 7:48 am ]
Post subject: 
yes this was discussed over and over some time back. Word has it 802.11b is just not fast enough. 802.11g is. you need a good steady solid 2.5Mbps for the video and 11b even though it's supposed to be 11Mbps generally doesn't provide a steady 2.5Mbps.
Author:  benotto [ Mon May 09, 2005 8:05 am ]
Post subject: 
Xsecrets wrote:
you need a good steady solid 2.5Mbps for the video and 11b even though it's supposed to be 11Mbps generally doesn't provide a steady 2.5Mbps.


I see. So I'm actually not too far. I should probably try a better antenna to see if I can improve connection enough to activate 802.11g.
Just for curiosity's sake, do you know if anyone has ever tried powerline network adapters?
Thanks

Luca
Author:  sanger440 [ Mon May 09, 2005 4:38 pm ]
Post subject: 
I just got my slave backend/masterbackend set up last night and did some testing. I watched maybe 20 to 30 minutes of recorded videos from the backend using 11g wireless. Both the backend and the frontend mythboxes use an atheros chipset 108g wirless lan card and my router is a Dlink 802.11g variety. My backend is downstairs and my frontend is upstairs in the master bed room. I must say it seemed to work very well. It took a few seconds to buffer on start up and then nairy a glitch from then on. 30 second fast forward and commercial skip seemed to work flawless.

I only streamed the recorded videos, not live tv. I have a TV tuner card on the upstairs box that should record to the backend downstairs. Have not tested this out, but it should work.

I have seen the airlink 108g routers for cheap at places like Fry's. And the 108g wlan cards go on sale real cheap as well. They seem to work real well in knopmyth using the mad wi-fi drivers.
Author:  tjc [ Mon May 09, 2005 6:34 pm ]
Post subject: 
You might try doing a network search for one of the little pseudo parabolic reflector PDF files. I think they were discussed on slashdot not too long ago. By increasing the directionality of your antenna they might give you a clean/strong enough signal for "g".

BTW - A search of the forum should turn up a couple really good conversations we had on why the "a" standard is hopeless and "b" doesn't quite cut it either.
Author:  benotto [ Tue May 10, 2005 10:51 am ]
Post subject: 
You mean something like this? http://www.turnpoint.net/wireless/cantennahowto.html

I also have another idea... I know this is almost OT, but maybe someone knows it (and it may be helpful to someone else, we all live in houses, after all!).

I have a power plug just the other side of the wall that is likely to constitute the biggest obstacle, so there probably is a short passage between the plug next the AP and the one on the other side of the wall: if I pass an antenna cable (assuming I use the best quality I can find) next to the power cables will interference be a problem? I estimate it to be no more than 40 cm.
I could then place a small antenna there and provide better signal to the rest of the house.
Author:  burgessms [ Tue May 10, 2005 11:56 am ]
Post subject: 
benotto wrote:
if I pass an antenna cable (assuming I use the best quality I can find) next to the power cables will interference be a problem? I estimate it to be no more than 40 cm.
I could then place a small antenna there and provide better signal to the rest of the house.


Be sure to check the cable loss spec for your cable. If you loose 6db in the cables, the 5db antenna won't be of too much help. The good, low loss cable is quite expensive, and a little larger than a wooden pencil. If you have enough of a gap in the wall, to get that fished thru, and are handy with soldering a nearly perfect RF connection, then it'd be useable, but not to building code. If you can keep the cable outside the J-box that houses the outlets, that makes it code complient.
60 hz won't get picked up on your wireless.
Mike
Author:  tjc [ Tue May 10, 2005 8:15 pm ]
Post subject: 
benotto wrote:
You mean something like this? http://www.turnpoint.net/wireless/cantennahowto.html

No, actually more like this: http://www.freeantennas.com/ You litterally print off the PDF or Postscript file and cut it out of lightweight cardboard faced with foil. It forms a parabolic reflector which gives a very substantial directional boost to the signal.
Author:  benotto [ Wed May 11, 2005 2:20 am ]
Post subject: 
Wow. It seems almost too good to be true!

Thanks. I'll surely try it.
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