I came across some settings in my new Netgear CG3100 that reminded me of the days when I used radio for communication.
There is a setting for Upper or Lower Sideband.
Those where the days, DX and QSL cards...
From the Wi-Fi settings of the Netgear Wireless Cable Voice Gateway CG3100
802.11 Mode: 11b/g/n / b and g only / b only / g only
Bandwidth: 20 Mhz / 40 Mhz
Sideband for Control Channel (40 Mhz only): None / Lower / Upper
Control Channel Current : 1 / 6