mrbloop

Yes it is 433MHz. Other things I've discovered… breaking the beams closer to the infrared transmitter side is a lot more accurate at triggering (it's perfect at distances of approx. 2m or less), I suppose this is because the beams are not very spread at this distance. The silver screw in the pic above can be used to fine tune horizontal adjustment (in addition to swiveling the lens housing by hand)

probably doesn't help then that I'm rather skinny! Going off that thought I decided to try reducing the amount of infrared light hitting the receiver sensors. Using some copper tape I crudely taped off the lenses, and low and behold it's now a lot more sensitive! Actually working ok now, not perfect but from the little testing I've done it's much better. I don't have time to test much further today but I'm certainly much happier with them now. In the manual it states that for this model the guarding distance is 100m and beam spread is 4.5m (I assume that is the spread at 100m?).

Hehe yes I kinda knew it was when buying. Though to be fair the alarm panel (GSM features and all) actually seems to work well (for my needs at least) …once I'd deciphered the 'chinglese' manual that is. Sometimes I don't mind taking a punt on these cheap chinese things, it lets me venture into trying new things that would probably be otherwise cost prohibitive.

Pics attached. Left one is receiver, right transmitter. The top lens on both has a red led indicator in it. Bottom two are the infrared related ones. The lens carrier can be swiveled horizontally and there is a thumb screw for adjusting vertical tilt. On the second photo you can see the jumper pins on the back of the receiver.

Thanks for the replies guys. Yes I think they are meant to be able to detect a person a walking pace. Hopefully I just need to fine-tune the alignment (they have horizontal and vertical tilt adjustment). In general how fussy are these infrared beam detectors when it comes to alignment? do they need to be absolutely perfect? or is there some leeway? Hi yes I did try that. The sensors themselves have a beep/light sequence when beam is broken so it's possible to tell when they are triggered even without the alarm panel, unfortunately it doesn't appear to be transmission signal problems. I wish they had built visible lasers for setting alignment, that would make it much easier. I have actually ordered a couple of cheap mini laser pointers to see if I can rig something up

Total noob here could do with some help setting up some dual beam sensors. I purchased this kit: http://www.ebay.co.uk/itm/302004674097 The goal is to use the infrared beam sensors on a long driveway to detect people or cars coming down, it will then send signal to the gsm alarm panel. I'm having trouble setting up the dual beam sensors (everything else in the kit seems to work as intended). I'm having trouble getting the sensors to detect reliably. I've lined the sensors up as best I can (using in built viewfinder) and there is a beep sequence which indicates they are correctly aligned (they are situated on fence posts about 1m off ground and 5m apart). However it's really hard to get the sensors to trigger. They might trigger 1 in 5 times when walking past them. If I deliberately stand in front of the beams to block them for a few seconds (about 3s) then they will usually trigger (not always though). If I bring the sensors back inside and line them up on floor a couple of meters apart and lie down on the floor between them then they trigger very reliably. A leg or arm blocking the beams is usually not enough to trigger, it seems to require my body for some reason. They certainly don't trigger reliably when just walking through at a normal speed (or even slow speed). Is this normal? do I need to fine-tune alignment to make them more sensitive? As mentioned I'm new to this. I was expecting the beams to reliably trigger when a person walks through them, was I wrong to expect this? perhaps they are more suited to detecting vehicles? The included PIR sensor triggers very reliably. Or maybe I just got what I paid for? Looking on amazon the reviews are generally very positive for similar cheap dual beam sensors. On the back of one sensor are 2 pins with a jumper on them, from reading the manual removing the jumper makes the sensors less sensitive (not what I want). Any help would be much appreciated.