[time-nuts] WWV/WWVH audio simulator?

[Magnus Danielson]

On 07/01/14 05:53, Tom Minnis wrote:
> I believe the Western Electric D1 channel bank was the first and the
> European standard came along later.  Then came the D2, the D3 and
> finally the D4 when integrated codecs finally came to be and it was
> practical to get rid of the common codec and do it channel by channel. I
> have tried to look at the spectrum of AM broadcast radio when they are
> taking phone calls and you can defiantly see the low frequency roll off
> starting around 300Hz for the guy on the phone and when the guy at the
> station talks, there are strong components below 100Hz.

First came the TDM replacements of FDM trunks, first system I know of is 
from 1953 and predates the Western Electric D1 channel bank by 9 years. 
It was only when TDM switching was introduced that things started 
coordination and standardisation, as the TDM trunks could be 
incompatible as the interconnect was done in analog signals.

Cheers,
Magnus