You attach your tracker in a similar way, but instead of using radio frequencies to transmit data back to you, the GPS system beams detailed information up to satellites in orbit that beam it back down to you – either on a hand-held display (PDA device) or computer.

You monitor everything using a website interface. Many of these devices interface with the popular mapping website MapQuest. If you cannot monitor your target in real time, one of the most powerful advantages of this tracking system is the fact that you can get automated reports that will give you a log of the target’s location over the course of a day (or even several days).

The cost of these systems is consistently falling, though the most potent and complete systems are still at least a couple thousand dollars.

Luckily, there are several variations of this technology that can give you options in the two, three, and hour hundred dollar range. For example, instead of planting a tracker on the target vehicle, you might use a “tracking stick” that you conceal somewhere on or in the target vehicle and retrieve it in order to collect (download) the surveillance data.

These sticks are smaller than a candy bar, and can run for up to a week on a pair of AAA batteries. Just plug it into your computer’s USB port, and you can retrieve the data in several formats, including HTML, Microsoft Excel, or Google Earth’s own KML format, which is custom built to handle 3D three-dimensional geo-spatial data.

Basically, you can monitor anyone who has a cellphone based on where and when they are using it. But there are a few conditions. There are a number of service companies who can easily set up this method of surveillance, but legally you must get approval from the owner of the cellphone you want to monitor.

If you are a father monitoring your child, this may not be an issue (especially if you are the one who buys the phone!). It’s more of a problem, however, when you need to spy. In the past, it was possible to circumvent this approval process by “borrowing” the target phoneand approving the tracking operation yourself.

This is of course against the rules. Today, these services are issuing periodic reminders to the cellphone being tracked informing its user of this fact. Nevertheless, it remains a much less expensive option for individuals compared to GPS tracking, as there is no need for additional hardware.

But there are a few conditions. There are a number of service companies who can easily set up this method of surveillance, but legally you must get approval from the owner of the cellphone you want to monitor. If you are a father monitoring your child, this may not be an issue (especially if you are the one who buys the phone!).

It’s more of a problem, however, when you need to spy. In the past, it was possible to circumvent this approval process by “borrowing” the target phone and approving the tracking operation yourself. This is of course against the rules.

Today, these services are issuing periodic reminders to the cellphone being tracked informing its user of this fact. Nevertheless, it remains a much less expensive option for individuals compared to GPS tracking, as there is no need for additional hardware.

These are small devices that can be placed under or inside the car bumper belonging to your tracking target. They are only a few inches long and wide, and attach to the bumper with strong magnets or double-sided adhesive. Their function is to assist you in following a vehicle that is under your watch. They are radio transmitters that will give you certain information regarding the bearing and relative speed of the vehicle being tracked.

These things are pricey too, $400 or so at the low end, and the more expensive units will be able to give more information with regard to the specific location of the vehicle.

A familiar tool for private detectives, bumper beepers give you an idea of how close to stay to the vehicle to avoid losing it, and how far away to stay to avoid detection.

One benefit of this method is that since antisurveillance legislation is focused mainly at the act of intercepting verbal or textual communications, laws in most places do not account for bumper beepers. They do, however, require a degree of know-how to be used effectively.

More importantly, digital technology and global positioning systems (GPS) make this a more or less obsolete option.

They can come with a microphone as part of the unit, and some more advanced models include zooming, tilting, and panning functions. Most webcams are used to monitor their immediate surroundings. They can be placed anywhere provided they can remain connected to their host computer or, if wireless, within range of it.

There is, however, a range of webcams that are “network cameras,” which means they contain their own web servers and connect directly to the Internet without the need for a computer on site. This enables you to see what it sees from any computer anywhere in the world that is Internet connected, no matter where the camera is placed.

These devices are more expensive than regular models and might not suit you if you have to leave the camera in potentially hostile territory. With any webcam, images can be sent immediately to the owner via email in the form of several still photos, or to a website that has been set up to stream images.

(Burglars have been caught in the act this way, and even despite stealing the computer that was transmitting the images!) Again, if you are covertly monitoring an environment, creative placement is the key.

Even though webcams are not typically built to be concealed, they are compact enough to conceal. Wireless webcams, which are not too much more expensive, might be even better toward this end. You may also want to consider using multiple webcams in different locations, which can all quite easily be attached to the same computer.

Most webcams are peculiar to either PC or MAC computers, and there are far more products available for PC owners. Apple makes its own webcam, however, for MAC users that is an excellent piece of equipment even if a bit pricier at $150.

It automatically sets the focus and exposure of the lens, and its builtin microphone delivers superior quality audio. In general, PC users can follow the “above or below $50” rule when choosing a webcam. Webcams under $50 usually have relatively low resolution – too low to print a picture from. For over $50 you will find nearly double the image resolution (at 640×480 pixel, or “VGA” quality). This resolution is considered as standard, with anything above it placing too much drain on your computer processor.

These items have a pinhole lens that is no bigger than several millimeters in diameter, and a resolution of over 300 lines. But bear in mind that smaller is not always better and it will almost always make things more expensive. A creative plant is much more important to your snooping success.

Concealed cameras can be fixed inside your home, such as in a clock or fire alarm for example, or they can be portable, such as in a boom box radio. Coupled with motion detection, they can be a potent part of your spy arsenal.

The concealed clock-radio camera, for instance, can be set to begin recording a few seconds after motion is detected, then switch off if there is no longer any motion. They can even be worn on your body, in a baseball cap or in a pair of sunglasses for example, recording everything you look at. Hidden cameras that are wireless typically transmit their video and audio back to a receiver that is up to 100 feet away.

Depending on the type of camera you use, you will be able to connect it to either your TV/VCR, camcorder, or computer for recording options. Some digital cameras can have built in digital video recording (DVR) capability, so that your footage can be easily transferred and stored to your computer.

Digital technology has vastly improved the versatility of this method, as digital images can be taken at a much higher resolution, and the footage is easier to study and store.

You can get a quality video surveillance camera for $50-$120 that includes audio as well, with color image and night vision at the higher end of the scale. Installation is a straightforward process.

If the unit will be exposed to the elements, make sure you are purchasing a system that is weatherproof.

Double that price and you’ll find a remote controlled camera that can swivel 360 degrees and see in the dark. If you are after a cheap and easy security device, you may even want to consider a dummy video camera, which uses motion detection to pan an area (and flash a green LED light) in order to appear as if it is actively recording. You can find one for under $30.

But it might only take one fleeting image to pinpoint a thief, an adulterer, or even a disobedient dog if they are caught with video surveillance techniques. Some general questions to consider before hatching your plan:

• Do you need constant video footage to monitor a specific location? This can be more labor intensive if you are using video tape rather than digital video because you have to constantly change the tape. In both cases, if you are not monitoring in real time, recorded footage is easily time and date stamped for quicker access.

• Does the camera need to be concealed? In the case of security monitoring, the very presence of a camera can deter any criminal activity – or even a fake camera, or even a sign that says that there is a camera on the premises (but not a sign that says that there is a fake camera!). In any case, you will obviously need to position this device so that it is not easily deactivated or vandalized.

• Does the camera need to be portable? Wireless?

Sometimes concealed cameras, such as one, say, hidden in a clock, are incredibly effective surveillance devices. But you can’t keep moving the clock around to different rooms without it looking quite odd. In this case a wireless webcam might be a better option, but it is of course more difficult to conceal.

Because of its cost, it is also not something you’d want to plant anywhere that there’s a risk of losing it. The important thing to remember is that with audio, all you need to do is expose the microphone in the direction of the targeted sound source; but with video, you will need to be more precise in how you aim the eye of the camera.

Motion detection and night vision are other options you have with video surveillance. It is possible to set video recording devices to record only when motion is detected.

And, for an added cost, you can purchase an infrared camera that will help you see in the dark (by sensing radiation and turning that heat into images on your screen. Any video surveillance system will include the same basic components: a video camera, a recorder / playback device, and a monitor. For wireless devices, include a transmitter and receiver in this list, although some devices bundle these functions into one unit.

In the past, these systems were difficult and costly to install. But they are continually getting smaller and less expensive; and anyone who owns a personal computer likely already owns most of the components necessary to implement one form of video spying.

They work in the same way as a baby monitoring device, but can be concealed in much more cunning ways (though you can find instructions on how to “hack” a baby monitor, which is a powerful audio transmitter, to quite effectively work as a concealed spy gadget). Wall Plug Transmitters Audio transmitter bugs come in all shapes and sizes and can be planted just about anywhere (a private investigator from San Francisco named Hal Lipset gained fame in the 1960s after successfully concealing a listening bug in a Martini olive!).

Some of the least expensive and most effective transmitters are available to you in the form a wall plugs and outlets. These devices are perfectly disguised and will clearly convey all conversation and sound from a 20ft square room. There are several variations as well, including plug adaptors and power strips that all would need to be disassembled in order to be detected.

There is, for example, a wall outlet transmitter that can be installed directly into the wall. Its advantage is that, because it is placed directly into the wall as a standard outlet, it is able to have a 3-foot long antenna that can be concealed by tacking it up inside the wall itself.

This device has a substantially greater range (over 1500ft), but of course is a bit trickier to install. In addition to wall plugs and outlets, you can find other devices that will perform the same function, such as a popular lamp audio transmitter that can be set to transmit only when the light is turned on. Most of these devices retail between $60 and $100.

It helps to bear in mind that if you are in the least bit technically inclined, you may want to consider putting together some of these devices on your own (the same might apply to you if you are on a super tight budget and have no other option!). For example, an audio transmitter bug that will retail for $100 can be assembled using electronics parts from a local store that cost under $5 in total.

With these bits, a few parts from a broken transistor radio, enough patience to wind a wire around a bolt, and a battery source to power it all you’ve got enough to get you going. Many schematics for assembly of such devices are available online, but perhaps the most reliable book on the topic is Brad Graham and Kathy McGowan’s 101 Spy Gadgets for the Evil Genius (McGraw Hill 2006).

To say cellphones are an epidemic would be an understatement. Everyone is either using, about to use, or has just finished using their cellphone for something. Every time they use it, there are signals that are sent through the air that, with the right equipment, may be yours for the taking – or at least yours for a peek before they continue on their way.

For several hundred dollars, you can purchase a cellular scanner device that will allow you to intercept cellphone transmissions. This requires that you are well positioned to actually intercept this cross traffic, and also does not guarantee that you will locate the transmission you desire. If you’re willing to up the ante to around $3000, you can get a souped-up version of this device that allows you to pre-program up to 20 cellphone numbers that will be recognized and intercepted automatically.

Advanced cellular interceptors can also provide the identity belonging to unknown cellphone numbers, hook up easily to recording devices, and be used as regular cellphone. Just in case you have just joined us, this method of audio surveillance, like most of the methods outlined here, is not legal. A final spy tactic involves a slightly different form of cellphone surveillance – one that actually turns the phone itself into a listening bug.

The Nokia 3310 Spy Phone is a popular example. You can leave the phone somewhere and then dial in to listen to the remote location (though admittedly it would seem a bit odd for anyone to leave their cellphone anywhere other than their purse or back pocket). You may even consider giving it as a gift to someone you’d like to keep tabs on. Sneaky.