This will save around 75 % of the power on an average on reverse channels.
2.
The modem was designed to use most of the bandwidth in a single direction, with a relatively low speed reverse channel.
3.
In the reverse channel, it places attenuation to block or " suppress " any signal on the assumption that the signal is echo.
4.
FEC gives the receiver the ability to correct errors without needing a reverse channel to request retransmission of data, but at the cost of a fixed, higher forward channel bandwidth.
5.
Instead of Bell 202, the European alternative V . 23 is sometimes used, ( without the 75-baud reverse channel ) or the data is sent using DTMF signalling.
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