Ideas for security problem

toxicmouse

Senior Member
I have a smallholding (homestead) that is remote. In the past 4 months it has been burgled 4 times. The issue is that I have a very large boundary and all the machinery/ equipment is sprawled around 2000m2, which is quite compact as the total stand size is 100 000m2. I need sensors that will detect when people are lurking about day or night, for which I am looking for ideas on this forum.

Part of the problem is that it will take 20 minutes to react to a situation, so the sensors themselves are at risk of being stolen, which is why CCTV cameras/ webcams with laptops for processing are not really an option.

IR beams would work but the burglars know exactly what the sensors look like and they are hard to hide. Maybe a few home made laser modules with sensors on the perimeter would be easier to hide. Any sensor that is obvious will probably be bypassed (and stolen).

PIR sensors are useless during the day but work just fine at night, and the PIR sensors that do work day/night are about 5 times more expensive than normal PIRs.

There are no trees, so LIDAR Lite V3 (sparkfun) is a nice option but I would need 6 units to cover the workshop area- gets pricey.

Ground radar worked out at R400 000 (USD 30 000), out of my budget.

Other ideas that I have thought of is vibration sensors in the ground (Distributed Acoustic Sensing) or some sort of capacitive cable on the ground to measure movements. I have no idea where to start with those.

Dogs are not effective as poisoning dogs is common here. I don't like the idea of a human guard as that is just putting a human life at risk.

My neighbours who live on their properties all use the same technique- lots of dogs and high powered rifles! I am not overly keen on following their example. Those who do not live on their property get everything stolen, even the roof, windows, doors and in one case even the bricks were stolen out of the brick walls- a real eye opener.

I would welcome any ideas.
 

julianE

Senior Member
I have been experimenting with these modules,

http://www.ebay.com/itm/LFS-DC04-2-7GHz-Microwave-Radar-Module-DC-5V-360-Degree-High-Level-Signal-Output-/311713408338?hash=item4893912552:g:ffUAAOSwpLNX9p15

Very simple to interface to the Picaxe. By covering the photocell it will work in daylight conditions or you can leave it uncovered for night only use. I've seen people remove the photocell permanently. If you look around they can be had for an even lower price.
You'd have to buy a number of them to cover the large area but it would give you a precise point of entry. You'd have to attach it to some inexpensive rf modules that would transmit a unique ID of the microwave module. Of course, the sensors would be tripped by passing animals.
 

techElder

Well-known member
... My neighbours who live on their properties all use the same technique- lots of dogs and high powered rifles! I am not overly keen on following their example. Those who do not live on their property get everything stolen, even the roof, windows, doors and in one case even the bricks were stolen out of the brick walls- a real eye opener. I would welcome any ideas.
You just presented a security problem that no professional security expert could solve for you (or you couldn't pay for that). Why would you expect to successfully experiment with hobby-level security and get better results?

Three questions:
  1. What is the value of property to be stolen?
  2. How much would you pay to keep that property?
  3. Can you move to somewhere more secure?
 

BESQUEUT

Senior Member
Maybe a few home made laser modules with sensors on the perimeter would be easier to hide. Any sensor that is obvious will probably be bypassed (and stolen).
+1 for that
plus : use IR laser and have fake sensors so that they will not try to find hiden sensors...
 

julianE

Senior Member
Sensor output goes high for 30 seconds when motion detected, much like some PIR modules.
The intended use for the modules is for motion activated lights hence the reason for the light sensor, if it's already bright in the room the lights stay off. I have had a module for a while now but I'm waiting for a larger shipment. My intended use is to detect when a delivery person approaches the house, should work well for that. It could possibly stay indoors since the microwave will penetrate through a door but I have not tested that feature. There is also a test option for a 4 second delay.

Erco, I'm shocked I found something before you, I have purchased many items you discovered.
 

toxicmouse

Senior Member
I have been experimenting with these modules,

http://www.ebay.com/itm/LFS-DC04-2-7GHz-Microwave-Radar-Module-DC-5V-360-Degree-High-Level-Signal-Output-/311713408338?hash=item4893912552:g:ffUAAOSwpLNX9p15

Very simple to interface to the Picaxe. By covering the photocell it will work in daylight conditions
Thanks julianE. I will definitely try these, I may find other applications for them. Any idea on the range that these modules work at on humans? At that price I can string them up with lots of redundancy.
 

toxicmouse

Senior Member
+1 for that
plus : use IR laser and have fake sensors so that they will not try to find hiden sensors...
Good idea. Maybe have some fake CCTV cameras with sensors attached so that I know when they are stealing the dummy cameras! Small chance of a false positive signal.

@Tex: I live in Africa, we have a lot of great things here but secure locations is not one of them. This is a great opportunity to come up with innovative security solutions that the professionals have not considered. Hobby level: tell that to the Wright brothers or any of the plethora of hobbyists who come up with great solutions. "Security Experts" in my opinion are people who tend to be ignorant and unwilling to learn, they call themselves experts because they know everything about their limited knowledge, Henry Ford had many bad things to say about experts in his autobiography. Hobbyists, in my opinion, are much more willing to learn and innovate, which is why you and I love this forum.

Thanks all for your great ideas. Please keep them coming.
 

Buzby

Senior Member
I too had not seen these microwave modules before, and now I've seen them I can see a solution to a specific problem I have.

The low cost of these surprised me. I didn't think even the Chinese could build a waveguide and whatnot for something like radar gun for less than $1, and they don't !. The device works by measuring the disturbance of a GHz continuous radio wave, and as such detects movement, not distance or static objects.

The GHz oscillator uses PCB tracks to make the necessary inductors and capacitors, so it's frequency is neither precise or stable, but that doesn't matter. The original purpose for these modules is controllers for room lighting, so there are lots of them, and they are cheap.

A really cool attribute is that they can be mounted inside a plastic box, with no lens or window needed. Great for hidden detectors.

Here is a write up :
https://github.com/jdesbonnet/RCWL-0516/

and if you want a different shape :
http://www.ebay.com/itm/1PCS-LED-3-12W-4-7m-Microwave-Radar-Sensor-Switch-Module-for-Bulb-Ceiling-NEW-/382002459918?hash=item58f11ef50e:g:K7UAAOSwIgNXjfD7

I've just ordered some !.

Cheers,

Buzby
 

fernando_g

Senior Member
Sorry to hear about your problems. I have an acquaintance who is a missionary and also tells me about the exceeding beauty of the African country side and the warmth of its people.....but that theft is rampant.

Anyways, the microwave modules hold a lot of promise. And at that low price, you can utilize many redundant locations.

My concern would be, how do you discriminate against wildlife? I ignore what type of animals roam in the vicinity, but some of them may be large enough to trigger a signal, perhaps?
 

Jeremy Harris

Senior Member
I've had one of these doppler modules working for around 6 months now, activating the CCTV camera recording system. They are far less susceptible to false triggering, and have reduced the number of false triggers I get to zero; the CCTV HDR only records real movement, whereas when I had a PIR trigger it would sense gusts of wind. They do need a larger object to trigger them, though, or at least mine does. I have it mounted inside a small IP66 plastic box, and it will trigger at around 5m with a human target, maybe 10m with a vehicle, but never triggers with small animals, like a cat. The PIR used to be triggered by cats all the time.

One down side is that these sensors are omnidirectional, the curious antenna/mixer design seems to produce as strong a field behind the unit as in front. This can be a nuisance, I found, as at first cars driving down the lane behind the sensor would always set it off. The fix was to mount the plastic box on an aluminium plate, to screen the rear of the sensor. This doesn't seem to affect the performance at all, other than to restrict the field of view to a bit greater than a hemisphere.

There are a number of different types around, and the one I'm using has a power mosfet switch. I'm directly switching the power to an 08M2, connected to an HC-12 transceiver, so that when power is applied an alarm signal is transmitted, then the unit waits until an acknowledgement is received (as a handshake confirmation) from the CCTV HDR controller (another 08M2 and HC-12, that switches the record line on the HDR). If no acknowledgement is received the unit continues to transmit alarm signals until the microwave module times out and turns the power off (around 30 secs).
 

julianE

Senior Member
Any idea on the range that these modules work at on humans? At that price I can string them up with lots of redundancy.
I did some rudimentary testing, they are supposed to be omnidirectional but mine is not, could be because I have it just siting flat on a table in a breadboard. I measured about 1.5 meters on one side and about 3 meters on the other. This is indoors, I suspect outdoors it will be better. I'm having a busy day and will test the current draw later. I suspect it will draw a goodly amount of current since it's meant to be powered from the mains for turning lights off and on. I suspect you can have some screening and aiming in order to only detect taller object so as to discriminate between animals and people.
 

toxicmouse

Senior Member
Thanks for the great ideas. I have bought 4 of these, waiting for delivery:

LFS-DC04 2.7GHz Microwave Radar Module DC 5V 360 Degree High Level Signal Output
 

julianE

Senior Member
Thanks for the great ideas. I have bought 4 of these, waiting for delivery:

LFS-DC04 2.7GHz Microwave Radar Module DC 5V 360 Degree High Level Signal Output
I just received a few more. They must make a ton of these, hence the price. Mine came in a sheet, I have to break off individual pc boards.

I measured the current draw, around 5 mA.
 

erco

Senior Member
And cordless phones and garage door openers?

What Buzby said: It's frequency is neither precise or stable

What I heard: Poor man's "spread spectrum"
 

julianE

Senior Member
And cordless phones and garage door openers?

What Buzby said: It's frequency is neither precise or stable

What I heard: Poor man's "spread spectrum"
I have had it on all day and no interference with any of the above. I also have my WiFi laptop right next to the module. Remember, these modules are meant to work with home lighting.

My radar theory is rusty, what I remember is that the doppler shift in frequency is in audio range. You compare the output frequency with the return frequency and the difference at that short a range is in Khz at most.

It does not have to be extremely stable because all you are doing is comparing the output frequency with the return echo but it's far from spread spectrum.

Of course, my engineering classes were a long time ago and I could be completely wrong :)
 

newplumber

Senior Member
Hi
I just found this thread so on the microwave modules has any of you had any problems with them
I am thinking of buying a few when they go on sale :) joking ( they are almost free anyway)
but its been a while since anyone added some test results but seems it would be the preferred motion sensor
another question is when it stops sensing a human movement does the output pin go to 0v right away or is there a 5 sec + pause
thanks
Mark
 

Buzby

Senior Member
I'm just in the process of building a proximity alarm using one of these modules.

Regarding time response, they go on as soon as movement is detected, and off just a second or two after.
 

newplumber

Senior Member
Thanks buzby
I will order a few and try them out ... is it possible to have the "off time" reduced to 250 or less Mill seconds or is it just programmed to a specific wait period
because the with a picaxe a person can control the rest but for like me in the future when i win the lottery I was planning on throwing some leds in when I pour my sidewalk
but not just boring leds but some kind of motion following ones ...the apa102 strips is all that i will buy now days they are very cool and after I test the microwave sensors
which they seem to be perfect for the job. I wish they made a motion sensing LED strip called something like a APA202 and you just program the brightness when detecting and the brightness when not detecting
then it would be super easy to install with a picaxe. Anyway its good to know different M sensors
 

Buzby

Senior Member
If you scroll down the first link in post #15 you will find some pinouts.

It looks like pins 3,4,5,6 are the ones controlling response and re-trigger times.

The existing performance is OK for me, and as the pins are connected to tiny SMD capacitors and resistors, I have no interest in experimenting with them :) .

Cheers,

Buzby
 

newplumber

Senior Member
I totally missed that post but awesome information ... now I have to wait for the "quick same year" shipping from china
 

Jeremy Leach

Senior Member
Maybe reduce the scope of the problem by focusing on any likely access roads people would approach your property by? Just a thought especially if some are very rarely used.
 

Peter M

Senior Member
IR works well over a long range if you focus it down a tube and receive it from inside a black tube..cheap n easy or the signs below may help :-O

 
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