PDA

View Full Version : When will 802.11g be available?



Christopher May
2004-09-19, 11:43
Is there any difference in signal strength in b vs g? I have a wirelss
network at work that always gives me dropouts, I think I have a lot of
interferrence.

Would I get better results if I went all b, or used a .g bridge and went
all g?

Chris

-----Original Message-----
From: discuss-bounces (AT) lists (DOT) slimdevices.com
[mailto:discuss-bounces (AT) lists (DOT) slimdevices.com] On Behalf Of
robin-lists (AT) robinbowes (DOT) com
Sent: Sunday, September 19, 2004 2:37 PM
To: 'Slim Devices Discussion'
Subject: [slim] When will 802.11g be available?


> -----Original Message-----
> From: discuss-bounces (AT) lists (DOT) slimdevices.com
> [mailto:discuss-bounces (AT) lists (DOT) slimdevices.com] On Behalf Of
> Julian Lomberg
> Sent: 19 September 2004 17:51
> To: discuss (AT) lists (DOT) slimdevices.com
> Subject: [slim] When will 802.11g be available?

[snip]

> As I understand it
> the bandwidth on 802.11b is just on the limit for uncompressed audio
> so I am quite likely to get dropouts if I try, hence it seems that I
> am doomed to be stuck here watching and waiting until an 802.11g
> version is released.

Not so. I stream uncompress audio and don't get dropouts (well, not due
to network congestion anyway).

Look at the maths:

CD quality uncompressed PCM audio consists of 44,100 samples per second,
each with 16 bits, x2 for stereo. i.e.

44100 x 16 x 8 = 1,411,200 bps (bits per second)
= 1.35 Mbps (Mega bits per second)

11b networking has a theoretical maximum bandwidth rating of 11 Mbps,
although in practise throughput is likely to be no more than half that,
i.e. 5.5 Mbps.

Even allowing for some protocaol overhead you can see there is plenty of
bandwidth to stream uncompressed data over an 11b network.

> I have considered competitive devices but most of them don't offer
> SPDIF digital coax output and that is the only input that my audio
> system will accept (it doesn't even accept analogue input of any
> kind).

What DAC are you using?

> I have also considered getting the wired version and buying a
> dedicated
> 802.11g bridge to interface with my network but that is just too much
> clutter and hassle.

It's not as much hassle as you might think, and it costs about the same
as a wireless SB, but I understand where you're coming from regarding
clutter - the wireless SB is a pretty neat and tidy solution.

Summary: uncompressed audio works fine over 11b. Go buy a SBG!

R.
--
http://robinbowes.com

Julian Lomberg
2004-09-19, 13:17
Wow, what a bunch of quick and helpful replies. Thank you.

In answer to a couple of specific questions asked of me:

My DAC is built into the speakers. The system is a Meridian DSP5000
active speaker setup with DAC, digital preamp and poweramps all built
into the speakers. I guess the closest "conventional" DAC is going to be
the Meridian stand-alone DAC of that era (about 6 years ago) which was
the Meridian 205 I believe (although I may well have got the model number
wrong).

As far as my signal path obstructions, I have 2 thick brick walls in the
way, one of which has built in cupboards and contents all along it. It's
tricky to know what the final 802.11b bandwidth will end up being. My
802.11g connection from a US Robotics access point to a Dell X300
laptop shows a full 54Mb connection for > 95% of the time, sometimes
dropping to 48Mb and very occassionally to < 30Mb but then for only
a few seconds. I do sometimes get total dropout for a few seconds but
that seems to be pretty random and my guess is that it is more likely to be
data collision with the 2 DECT base stations that I have in the house and
the 5 handsets.

Thanks for the maths on the data rate. I had done the maths myself and
come up with a similar data rate (I approximated it by assuming 720MB
of storage for an hour of music). Obviously the real calculation from the
sample rate and other factors is better than my guesstimate, but encouragingly
similar. It's actually the maths that gave rise to some of my concerns. Some
of the data I saw in reviews of 802.11b access points showed alarming
dropoff of performance with distance and you really didn't need to be
that far away (with obstructions) to be at < 2Mb delivered bandwidth, hence
my concern. I'm also concerned about an 802.11b device dragging down
the performance of my other 802.11g devices, but I believe that modern
802.11g access points don't revert all the way down to "b" performance
nowadays so "g" devices might show some degredation but not too bad.
Is this right?

How much data does the client buffer? How long a total-loss-of-signal
will the device be able to conceal (because of buffered data) before the
replay stream needs to be paused?

- Julian

Daryle A. Tilroe
2004-09-19, 14:08
Christopher May wrote:

> Is there any difference in signal strength in b vs g? I have a wirelss
> network at work that always gives me dropouts, I think I have a lot of
> interferrence.
>
> Would I get better results if I went all b, or used a .g bridge and went
> all g?

Personally if I were going to go with a bridge anyhow I would
seriously consider 802.11a. Get out of the noisy, crowded, 2.4 GHz
frequency band altogether. Myself, I had lots of signal strength but
my microwave always killed PCM streaming. Just went wired for the
two 'audiophile' hookups. Have a wireless for streaming MP3s on
the patio. You may also want to consider powerline transmission
if CAT5 is out of the question.

--
Daryle A. Tilroe