What is the problem "worth" to you? What is your tolerance for false alarms? What kind of activity is typical at the site? How much lighting do you have?
Outdoor motion detectors are an option, though depending on what you go with maybe not even the cheapest option. The pro's are they are relatively easy to install, don't require any lighting on-site and are simple devices (no moving parts, etc.). The con's are that they are very hard to tune to only cover the area(s) you want and to only pick up the object(s) you want alarms from.
The scenario you describe is what we (VideoIQ) specialize in. We have analytics embedded into a megapixel IP camera, and can give you much more precision and accuracy than what you'd typically get from connecting some motion detectors to standard cameras. Notifications to a phone (via email or an app) are also supported.
A typical installation of a couple of cameras, mounts, wiring, etc. is going to be a few thousand dollars minimum. However, many of the higher-end outdoor motions aren't much cheaper and I will say they are a lot less accurate and reliable. But, if you've got a really low budget and a site that doesn't get a lot of activity from animals and nuisances you might be able to get away with a really cheap outdoor PIR and a basic camera.
This question covers a lot of ground, but I'll make some assumptions about your situation:
When it comes to sensor tech, companies like Optex and Takex offer high-end equipment - so I'd be curious to know what you found after looking at those offerings. Chances are, if those offerings had a difficult time, less expensive commodity sensors would struggle more. As you've found, selecting the correct outdoor sensor is not a simple thing - there are many environmental variables like heat, humidity, precipitation, heat gradients, and line of sight that determine overall effectiveness.
Brian K is correct when he writes "A typical installation of a couple of cameras, mounts, wiring, etc. is going to be a few thousand dollars minimum. However, many of the higher-end outdoor motions aren't much cheaper". I cannot vouch for VideoIQs analytic accuracy, but he is right regarding cost. A high-end system is costly - and it still can be fraught with false alarms if improperly designed.
As far as remote notifications (email/SMS), those are generally a function of the alarm panel, and not sensors. Most modern alarm panels have a dialer module that can be configured to notify you, even if the system is 'unmonitored' by a central station. However, you might check Alpha Arsenal that sells simple PIRs that can be paired with GSM cards for 'panelless' remote notification.
You might also find our Xandem report useful. That intrusion technology is built around a 'tomographic' field that is immune to line of sight problems, and is tuned to alarm on human movement. The technology claims very low 'false alarm' rates.
Like Brian K offers, there are many factors that weight into the 'right' choice, and following up with more details about your situation will help get you the best answer.
Thank you for your help so far. It is not completely dark at night around the building since there are a few neighbor's lights (100-300 feet away, and a few dim and low landscaping lights). I was thinking about installing Optex VX-402RI (wireless) all around the outside of the building, but the specified install height is low, and I'm not sure if the tamper-proof kit would be enough to protect it. Also I really would like to have a camera tied to the motion detector in order to find out what triggered the motion detector. DO you know if it is possibel to send the wireless signal of the VX-402RI to a Visonic Powermax 30 which, in turn, triggers a wireless IP camera?
All else being equal, I would prefer to have the PIR-camera team on the same equipment already in order to make sure that the camera is getting photos at the same spot where the motion occurred. I've found a total of 3 products that have reliable PIR (least false alarm), and a camera on board. The only Optex PIR sensors with Cameras onboard (MRP3050S and SIP-3020CAM DN) have a really long and narrow range, which is difficult to arrange into a configuration that will provide full perimeter protection around the 70'x25' building. The advantages of these are that they have a camera on board, and a higher install height which will allow me to install under my roof overhang, and avoid most vandals. The downside, is the narrow range, the higher cost, and the fact that the onboard camera is not an IP camera, and I will need to install DVR, and it will be more difficult to see the picture remotely (ie from a browser or using the iphone)
Besides Optex, Visonic Next CAM PG2 has been advertised as having very few false alarm, and has a camera onboard. This seems ideal, but was designed for the indoor environment. I like the Visonic Powermax 30 also. For the outdoor, Visonic Tower 20AM is tauted as producing very few false alarms, but it does not have a camera.
I am still debating between Visonic and Optex. If I purchased Optex sensors, I may have to work with Inovonics Security Panel. Do you know if it is less user friendly, and if it is as good as the Visonic in terms of the wireless signal reliability.
First - as an idea for you: I have a number of these security lights around my house:
I have not used the model with an integrated security camera (it seems like a marginal unit), so I cannot comment on how well it performs or is managed. However, I have been very satisfied with the performance of the 'light only' models. Even in the cold and ice of winter, they have continued to work well.
Next - the claims of low false alarm are only due in small part to component quality. Avoiding false alarms is many more parts proper installation and specification. If you feel like you're pressing the sensor abilities to cover the entire range, you probably are. Unfortunately, the best answer is using more sensors.
Even if you are pressed into analog cameras, I think you will find most DVRs can be networked and seen remotely rather easily - many commercial DVRs even come with a free DDNS account and smartphone apps for remote viewing. (Speco, Ganz, and Digimerge come to mind, but there are many others.)
I cannot comment on usability or interface difficulty between Inovonics and Visonic. Both platforms use frequency hopping spread spectrum wireless, so individual performance is a matter of testing. However, both should perform well within design parameters.
I have a system set up at my business for this purpose, and it works very well. I use a Honeywell Vista 20P panel with Ademco outdoor motion sensors. I have a total of seven of these sensors up around the perimeter of the building. I started with 4 and added the other three over time, but in the three or four months since I installed the first four, we have had a total of ZERO false alarms, and they have never failed to go off when a person or vehicle is within range. These sensors are expensive- around $250 each, but I am really impressed with these sensors. I have some fairly expensive motion detector lights installed there, and they go off on false alarms at least a few times a week and many more if it's windy, but the Ademco sensors have NEVER given me a false alarm. I was less than excited while learning how to program the Honeywell panel, but it wasn't bad.
To get the notifications, I have an IP BAT from IP Data Tel installed . I have an account set up through AlarmSystemStore so I can have texts, phone calls, and emails sent. I just have it up to send text messages to two different phones, and it hasn't failed me. We get a lot of people sneaking around our building to hang out and do drugs, so I've had plenty of opportunities to see the system work. You do have to pay around $70/year for the IP Data Tel service, but it's very effective, and you can use it with an Android or iPhone app to access your panel remotely and arm/disarm. The Honeywell panel also lets you set up a schedule to arm and disarm it automatically.
If you really want to know whenever someone is out there and don't want to hassle with a lot of false alarms, I highly recommend this setup and must credit John at Alarm System Store for suggesting it to me.
As for cameras, if you just want something really simple that will give you a pretty good picture out to about 30ft or so, even in the dark, along with audio, I highly recommend the Sharx outdoor cameras. These are great for seeing and hearing what is going on at the moment and don't require an NVR. They record onto an onboard card, so you can watch clips from them as well. I wouldn't count on identifying an unknown person's face or a license plate unless the subject was very close, but you can definitely see what is happening at short range.
If you get a fair amount of traffic and want to run through your footage real quick each day, however, I suggest ExacqVision software. There are plenty of people on here who can suggest cameras, so I won't go into that anymore. I hope the above is helpful.
Glad you liked that. The system has really come in handy for us- it notified us when there was an unknown person at our office door at 2am. The person was apparently surprised by the light blinking on the motion detector and left before the police were able to get there. If he had decided to stick around and break in, I would have had at least had a few minutes' warning so that the police would have had a much better chance to catch the guy versus waiting until our glassbreak or door sensors tripped the interior alarm.
Two days later, a different unit in our building was burglarized! I think notification of someone in the perimeter is extremely valuable.