[Lowfer] Unknown signal/modulation on 475 kHz

[Garry]

Last night, in addition to 474.2 kHz wspr2 and K9KFR JT9 signals and 
KU4XR on 477 kHz Op8, two strong signals were seen here seemingly 
sending QRSS. But I tuned the one on 475 kHz and found it was not QRSS, 
nor was it Opera (see attachment). The dot transmissions lasted a bit 
over 10 seconds long. The other signal was on about 475850 Hz and 
appeared to be sending a similar short/long keying sequence with dead 
times between the keyups. Does anyone know what this modulation scheme is?
---
73, Garry, K3SIW, EN52ta, Elgin, IL
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