30m isn't really long range for any of the decent 433MHz modules. I have a pair of cheap HC-12 modules reliably working over a range of around that, through thick walls and effectively RF-screened glazing.
There is a LOT of 433MHz interference around, from the plethora of other devices that operate in this band, so if you have neighbours nearby, then there is a very good chance that everything from remote weather stations, through remote alarm systems to door bells will be on the same frequency. I got around this by using a pair of fairly cheap transceivers to operate an alarm recently. In my case it's just a unit where power is applied to a Picaxe 08M2 and HC-12 transceiver by an alarm sensor (I'm using a small doppler microwave sensor, but it could as easily be a microswitch or PIR sensor). At the receiver end I have an always-on Picaxe 08M2 and another HC-12 transceiver, plus a small relay. The relay turns the CCTV recorder on for a pre-set period, whenever triggered by the remote sensor.
To get around false triggering, I chose a sensor that only ever responds to object movement (originally I used a PIR, but had lots of false triggers from wind, shadows etc) as a first-line defence. The second line of defence was to prevent false triggering on the 433MHz signal, as there are a lot of 433MHz band signals around where I live, even though it's out in the countryside. The solution I chose was a "challenge and response" one. The alarm sends a challenge to the receiver, the receiver responds by transmitting a response to the alarm unit and the alarm unit responds with "this is a real alarm" to the receiver. Only then does the relay operate and turn on the CCTV recorder. I find I now get around four or five CCTV recordings a day, now (postman, us, occasionally a cat), whereas with the PIR I was getting well over 100 alarm trigger events on a warm day.
The total cost of my units, for both ends, was only around £15 to £20, including the cases.
