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Old 31st August 2011, 03:54 AM   #1
CLS is offline CLS  Taiwan
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Default Wireless Transceiver Latency Problem

Hi there,

Anyone uses wireless transceivers for transmitting AV singals?

I know there're several commercial HT products with 'wireless' rear channel speakers etc... However I need wireless only for stereo audio signal (to feed the subwoofer far away from the equipment racks).

So I bought a set of wireless transceiver. It's said to comply IEEE 802.11a protocol at frequency of 5GHz, by OFDM transmission and AES encryption -- all these specs are well beyond me. Oh well ...

Now here is the problem. The latency is so LOOOOooooooonnnng !!!

With the rest of my audio system connected by ordinary wires and the sub via this wireless transceiver, I can clearly hear the bass notes from sub are at least half a second behind the rest of the system. Just echoes ! Totally useless

Now what?

I guess there might be some kind of buffer for the video signal which contains much more information (and I don't need). Is it possible to bypass that portion?

Or, it's entirely another story about this whole thing?

Any inputs? Thanks in advance
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Old 31st August 2011, 12:59 PM   #2
DF96 is offline DF96  England
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Digital encoding and decoding takes time, as does the FFT performed at each end as a necessary part of the OFDM technique. All digital methods will have a delay, some worse than others. Only analogue can avoid this.
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Old 1st September 2011, 02:41 AM   #3
CLS is offline CLS  Taiwan
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Thanks for answering. Now I know it's no hope fiddling with it.

Back to the drawing board....
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Old 1st September 2011, 05:04 AM   #4
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Just a quick suggestion. I just bought a cheap, ($20) Sylvania wireless headphone system for listening to TV. The sound seemed to be in sync with the picture. It's an inexpensive unit, I'm sure it is sold under a variety of names.

A cable plugs into the audio jacks of the TV, goes to the wireless transmitter and gets converted to a radio signal which the wireless headphones tune into.

The whole thing certainly seems to be analog and seems to work nicely. Tear it apart, clip off the wires to the headphones and solder on some RCA plugs which you plug into the subwoofer amp, and you might have at least something to start with.
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Old 1st September 2011, 07:47 AM   #5
Elvee is offline Elvee  Belgium
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Quote:
Originally Posted by CLS View Post
Hi there,

Anyone uses wireless transceivers for transmitting AV singals?

I know there're several commercial HT products with 'wireless' rear channel speakers etc... However I need wireless only for stereo audio signal (to feed the subwoofer far away from the equipment racks).

So I bought a set of wireless transceiver. It's said to comply IEEE 802.11a protocol at frequency of 5GHz, by OFDM transmission and AES encryption -- all these specs are well beyond me. Oh well ...

Now here is the problem. The latency is so LOOOOooooooonnnng !!!

With the rest of my audio system connected by ordinary wires and the sub via this wireless transceiver, I can clearly hear the bass notes from sub are at least half a second behind the rest of the system. Just echoes ! Totally useless

Now what?

I guess there might be some kind of buffer for the video signal which contains much more information (and I don't need). Is it possible to bypass that portion?

Or, it's entirely another story about this whole thing?

Any inputs? Thanks in advance
The best solution, if practicable, is to pass all the audio channels through the same link.
Even if you add an external digital delay unit, you have no guarantee it will work every time, because the buffer size may vary according to conditions.
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Old 1st September 2011, 09:31 AM   #6
Enzo is offline Enzo  United States
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There certainly are a bazillion wireless systems for gutarists to go wireless. None of those delay the signal.

Are your delayed subs and your main speakers the same distance and direction from your ears?
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Old 1st September 2011, 12:09 PM   #7
DF96 is offline DF96  England
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Most wireless systems use analogue FM.

Incidentally, Ofcom (our UK telecomms regulator) is worried about the number of wireless audio channels needed for the 2012 olympics in London and is hoping that digital techniques will solve the problem. OK in a large stadium, where there is an acoustic delay anyway, but in a smaller venue the digital delay might be offputting to athletes being interviewed after an event. I think this is one area where analogue is definitely better.
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