[PPRAANet] low-level interference on 146.46?

[K3ILC]

I often monitor 146.46 during the daytime, with the squelch on. Quite 
often, the noise increases and I have to turn the squelch to a much 
higher level to silence my rig.  I discovered that the noise is actually 
a low-level FM(?) signal.  I can't hear any modulation when my rig is in 
the FM mode (because the signal's too weak), but when I switch over to 
USB, I can hear an FM signal -- sometimes there is modulation, as if a 
conversation is taking place, but other times, it sounds like some type 
of digital communication is taking place -- sounds like some type of 
scanning --perhaps SSTV.

I lately discovered that every 10 minutes, the signal identifies as 
K4RTV/L.  (I can copy the CW ID on the carrier, when in the USB mode).  
Does anyone know what this station is or does?  It appears to be a 
repeater of some kind.  Also does anyone know what /L stands for?

I looked the station up in qrz.com, and he is located in Westminster, 
CO.  I tried to send the op an email to the address listed in qrz.com, 
but the email bounced.

Any help in identifying what this station is and its purpose is 
appreciated.  The signal is weak enough so that it doesn't create 
interference on 146.46 QSOs at my location -- but I have to turn up the 
squelch quite a bit when it's on.

Jim
K3ILC