XSS is the Automatic Link Establishment address (ID) for the probable control station of the UK's new Defence High-Frequency Communication System (DHFCS). The control location is Forest Moor, England, though remotes are possible. It has been heard widely in Europe and the eastern US, but not out here on the Left Coast.
Not until today (UTC date 15 November), anyway. Several ALE soundings have been received on 14728.5 kHz. Here's the PC-ALE output:
[01:03:16][FRQ 14278500][SND][TWS][XSS ][AL0] BER 28 SN 02
[01:03:13][FRQ 14278500][SND][TWS][XSS ][AL0] BER 24 SN 02
[01:03:11][FRQ 14278500][SND][TWS][XSS ][AL0] BER 16 SN 01
[01:03:10][FRQ 14278500][SND][TWS][XSS ][AL0] BER 20 SN 01
[00:33:02][FRQ 14278500][SND][TWS][XSS ][AL0] BER 21 SN 07