If there was a device set up before Shabbos that every hour would send an IR (infrared) signal towards an appliance such as a fireplace to either turn it on or off, would one be allowed to cover that device with a cup to prevent the signal from activating the appliance on Shabbos? Infrared is a spectrum of light, so wouldn't covering it be okay if one is allowed to cover lights on Shabbos (the Kosher Lamp an example)?
An example of such a device is the BroadLink RM4 Mini: https://www.amazon.com/BroadLink-Cable-WiFi-Automation-Controller-RM4/dp/B0872PPSGM/
Edit: The IR is sent as a short blast of invisible light.
However I also heard that grama devices are not Halachically ordained. I don't have the source.
The Kosher Lamp:
The BroadLink RM4 Mini which sends IR blasts: