IP CAMERA LEARNING & RESOURCE CENTER

2-Way audio, or Bi-directional audio is a relatively new feature for many IP cameras, enabling the security operator not only to listen to sounds at the camera, but also to transmit audio to the camera. By connecting external speakers to the camera, operators can talk via the camera, giving instructions or warnings to intruders, or even play pre-recorded audio sequences such as barking dogs, police sirens etc.

Bi-directional audio opens up a whole range of opportunities and improvements to surveillance. Control room operators can now interact with an intruder while capturing their actions, buying valuable time to capture identities and further critical evidence for prosecution.

No only this, but 2-way audio makes network cameras idea video conferencing tools, video or weblog recording devices and even permanent office-to-office communication tools. The possibilities are huge.

LAN stands for Local Area Network and is the term used for all computers, IP cameras and other network devices which can be used without using a router to access the internet. Devices on a LAN can most often communicate with each other (I.E. file sharing) or can share resources such as printers and internet access.

WAN, on the other hand, stands for Wide Area Network and means any network that covers a large area, say a government network spanning a country, a large company’s network linking offices or the internet. These also share information, with the most common example being websites.

A network switch is a device which allows more than two network devices to be linked via Ethernet. As Ethernet is a 1-to-1 connection, only 1 device can be connected to another. A switch offers multiple network ports on a single device and contains electronics to send the right information to the right device. Switches are nowadays set to work at either 100 or 1000 Megabits per second, but are also backward compatible so that older devices which operate at 10 Megabits per seconds can connect.

Ethernet switches usually come with 8, 16 or 32 ports. Most home routers usually have a small switch built in and allows a few network devices to be connected. Aditionally, switches can be connected to each other by Ethernet cable which allows an unlimited number of network devices to be used on your network.

A Crossover cable is special kind of network cable which allows two network devices to communicate without the need for a switch or hub.

For those of you who have tried to set up an IP camera by plugging it directly into your computer you will have found that the two devices will not communicate. This is because network devices expect to be plugged into a switch to control the transfer of data, rather than directly into another device. A crossover cable will allow you to do this.

Ethernet cable is made up of 8 wires. With a standard Ethernet cable they are arranged in the same order from one device to the next. However, four of the wires are switched with each other in an Ethernet crossover cable. This allows the two devices to connect with each other as if an Ethernet switch and two straight cables were being used.

Ethernet cables are usually defined by having plugs which are a different colour to the rest of the cable (see image below), but you can usually tell a crossover cable apart from an ordinary ’straight’ cable by the wire positioning within the connector.

In home networking terms, Ethernet is a standard for transmitting data. Each device that wishes to communicate will need to have an Ethernet network port and cabling (see RJ-45).

For home networks, there are, at present, three speeds of Ethernet. 10Base-T is the slowest and oldest Ethernet standard which will communicate at 10 megabits per second (Mbps). Following on from this is 100Base-T, which most modern PCs use this and will communicate at 100Mbps. The newest standard is 1000Base-T which will transfer information at 1 Gigabit per second (1000 Mbps). Most Ethernet devices are marked with the connection speeds that they can achieve. Most are marked 10/100, meaning that that they can communicate at both 10 and 100Mbps. More modern equipment may be 10/100/1000 which will also work at gigabit speeds.

Ethernet is a 1-to-1 connection meaning that a cable cannot be split at random and connected with another device. Ethernet cabling must be run from one port to another. When connecting devices, say a computed and an IP camera, an Ethernet “switch” must be placed in between the two to transfer information. Alternatively, an Ethernet Crossover cable may be used.

One thing to remember when planning an Ethernet network is that the network is only as fast as its slowest connection. For example, if you have two computers capable of gigabit transfer speeds, but have a switch in between which is only capable of 100Mbit, the information will only be transferred at 100Mbit. This is not a problem if the network is only being used for small data transfer, say internet access, but should be considered when the movement of large files is expected, for example the daily backup of a IP camera recording server.

E-Flip or Electronic Flip is a feature found in some PTZ cameras which have a 180° tilt.  It allows a moving target to be tracked when they move directly underneath a security camera. Normally if a target moves underneath the camera the image will be upside once it has passed the 90° point.

What E-Flip does is detect the position of the camera and automatically flip the image to the correct orientation so that it will always appear the right-side-up.

For security monitoring this allows quicker response time from the camera as a conventional CCTV camera with a 90° tilt action will have to rotate 180° before allowing the operator to continue tracking the target. It also makes following a moving target much simpler.

Iris

The Iris is a component in a camera lens which can be opened or closed to let in more or less light to the imaging sensor. This helps balance the exposure of the image so that the camera can provide a high quality image, ideal for security applications which require fine detail such as being able to recognise faces or objects.

In a large security surveillance and monitoring system it is not realistic to expect the operator to manually adjust the iris of each camera according to lighting conditions, especially if they have a large number of cameras or for cameras which are located outdoors. Using a camera which includes an auto iris lens provides a solution. The camera will detect the amount of light entering the lens and automatically open or close the iris to provide an image of the correct exposure.

Outdoor use

Cameras with auto-iris lenses are recommended for outdoor use as light can change dramatically throughout the course of the day, especially if the sun is prominent in the image to be captured.

Manual

Some fixed cameras come with manual iris lenses which can only be set on the lens once before the camera is installed. These cameras usually have routines and settings in the software to help adjust the exposure.

One of the main uses for IP cameras today is security for your home or business. They are great tools for monitoring your property and can provide instant feedback when alarms have been triggered. Sometimes though you may want to switch them off.

Scheduling

A camera which is installed in a home is perfect for alerting you to intruders when you are at work or on vacation but in the main, it’s not neccessary to be alerted when you are at home. This is where scheduling becomes useful.

As part of setting up alarm events in the camera (such as a motion detection event), most IP cameras today also offer the scheduling of events allowing you to specify when the camera should alert you and when it shouldn’t.

An example would be to set a schedule which activates motion detection events during the day while you are at work and turn off at the time when you return home. This means that the camera will only send emails throughout the day when you are not home, otherwise your inbox would fill up with pictures of yourself at home, which isn’t entirely useful to most people.

Recording Software

Scheduling also forms a large part of how recording software operates as a system can be set up to do many tasks automatically, making the operators role streamlined and more efficient, especially if the security system contains many cameras. In some applications, other tasks such as archiving, gaurd patrolling, emailing etc. can all be set to a specific schedule, sometimes on a per-camera basis.

An example of a schedule displayed in graphical form - Panasonic BB-HNP15 Network Camera Recorder

There are many IP cameras available today which have a zoom lens and this allows the camera to enlarge areas of a scene so that more detail can be seen from distant objects. This is not to be confused with digital zoom, which is another feature entirely.

Technically, the way that the lens achieves a level of magnification is by adjusting its focal length. On zoom lenses this can be done mechanically using the camera’s controls so images can be zoomed from a remote computer once the camera has been fixed in position. Mechanical zoom cameras will usually have an auto-focus feature to allow it to refocus once it has been moved. The other type of zoom lens is a varifocal lens and these in general have a fixed, manual zoom as they are normally found on static cameras. Once a varifocal lens has been set to the required zoom (and manually focussed) it cannot be adjusted without physically adjusting it at the camera.

Focal Length Vs Viewing Angle

Simply put, the viewing angle of the camera will become narrower when you zoom-in. This corresponds to the horizontal and vertical viewing angles. As you zoom-in (telephoto) you will start to narrow your field of view as you magnify one particular area of interest. It is important to check, especially with fixed varifocal lens cameras, that the lens will give you the required shot before you purchase.

Zoom Ratio

Most zoom lenses present their zoom capabilities by using a number such as 3x or 10x etc. This is known as the zoom ratio. It is determined by calculating the ratio between the cameras focal length at the telephoto (zoomed-in) position and the focal length at the cameras wide-angle (zoomed-out) position. IP cameras with varifocal lenses will typically have a zoom ratio of about 3x but some of the high-end PTZ dome cameras can have as much as 30x/35x zoom giving them the ability to capture distant subjects in extremely high detail.