# Network throughput between 2 sound cards?

#### foxkm

##### Senior member
I am curious, what if we were to take 2 say SB Audigy's and develop some special software which turns the sound cards into some sort of network modular/demodulator tap? This would of course be done by taking 2 sets of male to male 3 wire headphone jack and going from Speaker out to Line in o the other side. How could I calculate the maxium capable throughput by converting a datastream into analog audio and being reprocessed back into digital data back on the other PC? Need to remember that we are transmitting in stereo in each direction so we can have 2 data streams going in each direction? Remember over a analog phoneline we can acheve over 56 kBit/second, and that quality is horrible...

Anyone have any insight?

#### Description

##### Banned
It depends on the innards of the sound cards. Is it 44.1kHz or 48kHz audio? How much of that signal is lost in transmission or processing?

The bitrate for CD-quality AIFF is 1411kbps, so you could expect at least that much.

#### AndyHui

##### Administrator Emeritus<br>Elite Member<br>AT FAQ M
Why bother? Simply use the Firewire interface on the Audigy.

#### foxkm

##### Senior member
Originally posted by: AndyHui
Why bother? Simply use the Firewire interface on the Audigy.

The question here doesn't deal with the obvios answer (use the technology already implemented), it asks a theoretical question as how much data can one actually push through the ananlog output on a standard sound card.

#### uart

##### Member
The "Shannon Capacity" is over 500 kbps for each channel.

This theoretical maximum bitrate is given by,

C = W log2(1 + S/N)

Where W is the channel bandwidth and S/N is the power signal to noise ratio.

Working with conservative values of W=20kHz and S/N=80dB (equiv power ratio = 10^8) give a little over 500 kbps per channel.