The UNID 1 PPS signal remained active til at least 2018-04-11 22:30UTC when I last checked.
Some observations,
The UNID 1 PPS signal remained on 7285kHz from the time CaptKliegle reported it at 2018-04-11 11:13UTC until I last checked at 22:30UTC
At 2018-04-11 20:00UTC China Radio International started broadcasting on 7285kHz but the UNID 1 PPS pip could still be heard, at least at my location. I did not note when China Radio International stopped broadcasting and I am not sure where the transmitter for this broadcast was located - maybe Cerrik Albania ?
Having had a bit of time to poke around, I started to check about for the PIP or ditter than Token has reported. I noted quite a lot of interesting activity.
Firstly, above and below 7285kHz I noticed PIP's every 3 seconds (approximately), one was 35kHz above at 7320kHz and the other 85kHz below at 7200kHz. further searching found PIPs every 120kHz at (6960kHz - not sure but I thought I could hear this one), 6900kHz but nothing lower in frequency; 7440khz, 7560kHz, 7680kHz, 7800kHz, 7920kHz, 8040kHz, 8160kHz, 8280kHz, 8400kHz, 8520kHz, and 9300kHz . All with an apparent repetition rate of once every 3 seconds (approx) except 9300kHz which appeared to be every 6 to 7 seconds I measured pulse width from a simple recording using audacity at 128ms which is interestingly 8x the pulse width of the UNID 1 PPS signal on 7285kHz (16ms pulse width).
Time wise, this was all between approximately 2018-04-11 16:00UTC and 17:00UTC
Also noted where PIPs on 7880kHz, 7640kHz, 7620kHz, 7400kHz, and 7300kHz all with an apparent repetition rate of once every 6 to 7 seconds (approx)
Furthermore, I noted another set spaced 110kHz apart at 7460kHz, 7570kHz, 7680kHz, all with an apparent repetition rate of once every 3 seconds (approx) and another on 7920kHz also every 3 seconds.
All of these nice and neatly spaced and repetitive PIPs has me wondering whether or not these were real signals and not just some artifact of my SDR receiver (airspy HF+) and computer BUT most were quite weak and others a bit stronger and all exhibited fading as would a signal which was propagated rather than locally created. Still, this is something to consider with respect to these other PIPs I was hearing and seeing on the SDR waterfall. Was I chasing my tail or where these PIPs real signals?
I did not note any double PIPs but occasionally one may have been dropped or just not heard as a result of fading.
Whether these PIPs were related to the UNID 1 PPS on 7285kHz is uncertain.
Whether these PIPs were related to the PIP or Ditter signals that Token has reported is uncertain other than being of a similar pattern and repetition rate.
cheers, Graham