Monday, February 24, 2014

Nyquist, Pauli and reserves

C/B = log_2 ( 1+SNR)

where C is the channel capacity in bits per second; B is the bandwidth of the channel in hertz (passband bandwidth in case of a modulated signal); S is the average received signal power over the bandwidth (in case of a modulated signal, often denoted C, i.e. modulated carrier), measured in watts (or volts squared); N is the average noise or interference power over the bandwidth, measured in watts (or volts squared); and the signal-to-noise ratio (SNR) .

So lets assume the firm or household want to know the most it can the soonest, then the economy samples C at twice the bandwidth, or C/B = 1/2. (2**1/2)-1 = SNR = .4. But that number is split in a queuing network, the sender gets .2 the receiver gets 2.  Add in congestion and the number goes to .15, or thereabouts.  Real scientists can get the right number, but it is a constant.  It is determined by the need to get the most information with the best transaction rate.

So for physicists, assume the particle and you get the natural uncertainty.

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