Sub GHz Listening Bridge?

For some of us, a driveway sensor can't be simply motion-based, due to activity in the area. I'm one such person. For this reason, I went with installing a Mighty Mule driveway sensor which detects changes in magnetic fields due to moving metal near it (ideally a vehicle, but can be triggered with metal garden tools as well I've learned).

The sensor itself is battery operated, sending radio wave signals to the indoor alarm unit, which is powered by a wall plug. As best I can tell, the alarm unit primarily interprets signals showing activity and low battery from the outside unit. It doesn't on its own have any smart features. As covered in some of the topics involving the HubDuino, some users have managed to wire in the alarm station unit to give it integration with Hubitat. Though I admire the project, it's a bit beyond my own capability, and the end product looks like it could be a mess of wires unless you're very skilled at cobbling together this sort of thing.

I recently obtained a Flipper Zero. Using it's Sub GHz raw feature, it could record and imitate the specific signal sent by the driveway sensor when triggered. I've not hit a low battery yet, so it's unclear if a specific signal ping might be used to have the alarm unit show low battery or if the system detects some level of weakness in the signal to indicate low battery. Since the signal can be easily recognized though, this got me thinking, would it be possible to integrate the device with Hubitat using something that skips the Alarm unit entirely? Is there some sort of smart device that can be used to listen for and react to specific RF signals and be used to trigger actions on a Hubitat? Maybe something with a Raspberry Pi and the right RF dongle exists that could be tuned to such a purpose? I would think something like this might also be useful to bridge other devices that use distinct, but easy to recognize RF signal bursts.

Another thought, though I assume this would be a stretch, could a Hubitat unit itself be used to listen for specific RF signal bursts? Clearly the Hubitat has a radio receiver, but I'm sure it's more complicated than simply writing up a driver that could accomplish this. Any advice on this topic is appreciated.

it is more trivial than you imagine, to solder a "PCB relay" coil to an LED output or the beeper. Then wire the relay contacts to a zigbee sensor.

Far less complicated than adding a RPi with a radio interface for the Mule (318mhz) which does not share radio bands with zwave or zigbee.

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I like this idea, done similar on other use cases. If OP takes this path I'd like to know how, or if, he is able to differentiate between activity and low battery.

The low battery and alarm have their own individual LEDs. I assume it would be a matter of using those, if I went the solder route.

I'll take that as sound advice. Just wondering if there was a cleaner way to do it. I guess it gets complicated, either physically or in terms of programming.

It looks like I'm going to try going with the option this video shows:

I admittedly found it a while back and wasn't pursuing this since I couldn't find this exact brand of contact sensor. However, I just found one that looks substantially like it and, by watching the video a few times, I notice an important detail.

It appears not just any contact sensor will work for this, but a contact sensor with external relays, commonly for use with garage doors, makes it possible.

I've ordered one and will try it out. As best I can tell, it seems this method could be used to detect any LED indicator on the alarm unit, including the low battery. I'll test it out to confirm I can do this with at least one sensor, then a second one for the battery. It does involve soldering, but the end product doesn't look like it will be that messy.