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Connecting up a weather web-camera

This section describes connecting up a weather web-camera to power and a network. Covered are USB leads, Ethernet network connectors, Power-over-Ethernet, the issues of navigating cables and, alternatives to cabling like Ethernet-over-Power, Wi-Fi and 3G Networking.


USB leads

USB webcams receive their power and transmit their images along the same USB lead. A USB lead combines both data and power into one cable, with power for the web-camera being supplied by the connected computer or USB hub. This means that in general, USB web-cameras have no need for a separate power brick.

Picture of USB A and B plugs USB leads terminated in either A (top) or B style plugs, carry both data and power, however, they can only trail to distance of five meters (15 feet) away from a computer or USB hub. This constraint afflicts all USB devices including external disc drives and printers.

The ideal location for a weather web-camera will often exceed this distance. So called USB extenders can increase this range in multiples of five meters, but they become costly and are far less reliable than a long-range network cable.
In fact, many long-range USB extenders use network cable anyway.




Ethernet networking

Ethernet is the name used to describe the most common form of computer network. Even through USB is sometimes used to build networks, USB is not a sound alternative to Ethernet. Ethernet is designed to be robust, flexible and scalable.

Computer networks are built around devices called switches, hubs and routers. All of these devices act as some form of a central node into which are plugged computers, printers and other switches, hubs and routers. Collectively, a group of computers networked together is called a Local Area Network or LAN.

A LAN could be made up of many hundreds of PC's in an office building or, be just a single home PC plugged into a cable modem; the cable modem itself being a router. Many LAN's converge together to form a Wide Area Network, or WAN. Generically, all WANs added together form The Internet.

All devices connected to an Ethernet network communicate with each other
using internet protocols.

An IP Camera uses internet protocols, which is how it can communicate across the internet without requiring an interviening computer. And hence the name, Internet Protocol camera.

Pictured, an IP web-camera connects to the world over a local area Ethernet network via the RJ45 socket at it's rear. This network is then probably accessible across the Internet.

In the home, there needs to be a corresponding and spare network port on the cable modem to connect the web-camera to.

Too often, both network and power cables shipped with an IP web-camera are far too short to be of any practical use. Custom leads will need to be fabricated.
Picture of the connections to an IP camera


Wireless or Wi-Fi Networking

The advent of Wireless Internet (WiFi) means it is easy to avoid Cable Hell. With a range of around 70 meters (200 feet), a Wi-Fi IP web-camera can prove to be a worthwhile investment.

The wireless web-camera connects to a network in exactly the same way as does a wireless Laptop. Furthermore, they can be configured to exploit the benefits of Wi-Fi security (such as WEP and WPA-PSK). Simply, there is little chance of a web-camera being hijacked by an unauthorised person sat in a nearby parked car with a wireless laptop.

Once again, the availability of a power source should be considered, especially as Wi-Fi web-cameras consume more power than their wired equivalents. Using batteries to power a Wi-Fi camera for more than a few hours is impractical as some cameras consume up to five amp-hours (1 amp at 5 volts over 1 hour). Solar panels charging a battery is an astute solution for powering a remote weather web-camera, but as an energy source, solar is unpredictable and expensive.


With more homes having wireless routers, a wireless web-camera can save a lot of disruption. Although there can be some frustating issues with getting a Wi-Fi web-camera to talk to the network that it is meant to be connected to, on balance, Wi-Fi is often a lot less stress than having to dig up floors and risk puncturing holes in the plumbing!

Picture of wi-fi signal finder When installing a Wi-Fi camera, or any other Wi-Fi device, a hot-spot finder or bug sniffer is a useful gadget to have. It quickly confirms if the device is actually transmitting.


Using a 3G Network

The connectivity offered by 3G mobile phone networks offers another means for connecting an IP web-camera to the internet in remote areas or, in urban places where a conventional Wi-Fi or DSL connection is unavailable. You can even use the technology to create a webcam from a moving object, like a river boat, a tour-bus or a locomotive cab.

There are many means of connecting to a 3G network; a 3G enabled Smart Phone, a Tablet with 3G built-in, or a USB dongle that plugs directly into a laptop. There are also dedicated 3G Routers that function exactly the same as a wired DSL router. With multiple Ethernet ports and a built-in Firewall, the only difference is the internet connection is achieved by transmitting over the mobile network's airwaves. Some 3G routers require a separate USB 3G dongle to function, whilst portable pocket-sized devices called Mi-Fi Dongles, have everything built-in.

To connect to a 3G network requires a dedicated Data SIM. A Data enabled SIM gives access to the network operators speedy 3G network, rather than a conventional cellular SIM which may offer internet access using the far slower GPRS mode; which is of no use to man or beast.




Some points to consider about 3G. As domestic 3G is designed for downloading social content, upload speeds are limited. Uploading streaming video is not so reliable unless, you just so happen to live underneath a 3G tower.

Web-cameras connected to 3G routers can only push their images on to a server. Images cannot be viewed from the web-camera ad-hoc. This is because 3G networks are configured so users are effectively inside a Local Area Network of the tower they are connected to. Therefore, the user has no unique or static IP address. Frustratingly, even when using a Dynamic DNS service, the 3G router cannot be accessed from the outside world because the tower's IP address is not exposed to the web. As the router's ports cannot be mapped to, any camera configuration, control and trouble shooting needs to be done router-side.

Although 3G devices have quoted speeds of 3.6Mbps thru 7.2Mbps, practical 3G network reception is susceptible to local terrain, the number of other connected users and meteorology; like rain, hail and that once in a lifetime weather event! Signal strength and throughput speeds can fluctuate from minute to minute. Adverse Network Breathing can drop connections or worse, force the 3G modem to default to it's disastrously slow GPRS mode. Low speeds may result in an uploaded image being partly greyed out because the connection timed out. Streaming video is only practical when the image size is small, the frame rate is low and the compression ratio is high.

As 3G costs by data volume and not time connected, a 3G router can be always on. However, when compared to DSL, 3G data tariffs are expensive and restrictive. Pay-as-you-go tariffs limit both data and days, and top-up regimes are often confusing. For contract tariffs, 3G providers are unlikely to provide a duplicate SIM for use in your camera. Unlocking a 3G from it's parent network allows a data SIM from any competitive operator to be used. Be sure the price charged for unlocking doesn't exceed any cost savings as, some network unlocking charges are dearer than buying a whole new dongle for the other network!

Picture of a USB 3G Dongle
3G routers either come with a 3G modem built-in or require the addition of an external USB 3G dongle.
As a rule of thumb, when used for uploading images from a weather camera, a 1Gb data SIM provides enough resource to upload over twelve thousand images. Over the 30-day lifespan of a typical pay-as-you-go SIM, this equates to sending in daylight hours, one image every four minutes. As 3G networks charge by data usage, use the camera's scheduling feature to avoid sending images when they are not required. Set image quality, and therefore the amount of bytes transmitted, to the minimum needed. Changing quality from excellent to good makes no discernable difference to the viewer but, could extend the top-up period of a SIM by a third!



Ethernet Over Power

Where it is impractical or even dangerous to have Ethernet cables sprawling around a dwelling, the mains wiring can be safely borrowed to provide a fully functional computer network.

Also termed Networking over mains, Powerline networking or HomePlug AV, connecting up a network using the mains sockets requires plugging a master network adapter into a power socket and then, connecting this to a DSL router using a conventional Ethernet cable. Slave network adapters are then plugged into power sockets around the dwelling with, an Ethernet cable from the slave being plugged into devices like games consoles, media servers and IP cameras. And all without drilling or crimping! The network is configured with a web based screen in the same way as a router or an IP camera. Most PoE devices will run at 100Mbps or more. The Ethernet cable from the slave can be up to 100 meters long. If a power socket is in proximity to a web-camera, EoP could be an elegant solution that should be up and running in just minutes.

On the minus side, EoP devices are still an expensive option when compared to the cost of an Ethernet home cabling kit and, may be outmoded by advances in wireless Wi-Fi networking.

Furthermore, controvesy surrounds EoP regarding it's impact on shortwave radio reception.
Data is piggybacked onto the mains current using frequencies that span the High Frequency band from 3 to 30MHz. In operation, a building's unscreened power cables act as a giant unbalanced loop aerial that fills the space with radio noise; which might jam certain HF bands, thus rendering shortwave reception impossible. Neighbouring homes within noise range may also be affected. Although EoP products must comply with FCC Regulations, the technology is not without it's detractors. Conventional Medium Wave, FM and DAB radio reception should be unaffected.

Picture of EoP adapters - Courtesy Netgear Although they can go anywhere inside a dwelling, EoP is still an expensive option for which there are alternatives.


Cat-5 Ethernet cable

The cable used on an Ethernet network is described as UTP cable, which stands for unshielded twisted pair. Inside, the cable has eight cable cores arranged as four twisted pairs, but unlike with audio and video cables, there is no foil shielding around the inner cores. It is the twisting alone that provides a degree of isolation from interference from outside the cable and, allows the cable to carry data at very high rates up to a distance of 100 meters (300 feet). Often, the cable is named by its specification schedule of Category-5 (think of the worse hurricane level), which is abbreviated to Cat-5 or Cat-5E. Network cable is terminated with an RJ45 module (wall socket) or, an RJ45 plug. Cat-6 cable is very similar, but will allow even faster data transmission rates.
Picture of network cable
Each length of Cat-5 cable can run to 100 meters (300 feet)



Power over Ethernet

IP web-cameras that use Ethernet network cable can be up to 100 meters (300 feet) away from a DSL router, which gives significant flexibility when positioning a weather web-camera. In practical terms, both network and power supplies must be considered. Although network cables can be over 100 meters long, the power cables fitted to the power bricks supplied with an IP camera are often an inconvenient meter in length; which means some form of power extension is required.

An effective solution is to use network cable in a similar way to a USB cable, by supplying both data and power along the same cable. This technique is called Power-over-Ethernet, or PoE.

Ethernet cables are made with eight cables inside, but only four are ever used for transmitting data (the green and orange pairs). The other four cables (the brown and blue pairs) are assigned for passing direct current. In most computer networks, these four cables are never used. The implication being that in many networks, 50% of copper is waisted!

Power-Over-Ethernet uses two devices; the sender/injector and the receiver/splitter. The sender connects to the network and to a power supply brick. Normally the power supply provides a voltage from 7 to 48 volts DC. The sender unit then connects along a single Ethernet cable to the receiver unit; which can be up to 100 meters (300 feet) away. The receiver then splits the single cable back into two; a regular Ethernet cable and a regular power cable.

Importantly, the longer a PoE enabled cable, the greater the voltage drop: a five volt power brick at the sender end, may only muster three volts at the receiver. Which is insufficient to energise a web-camera! With long cable runs, an alternate power brick is necessary. Furthermore, the most power flowing through a Cat5 cable should really not exceed fifteen watts: thus a 12 volt input, regardless of voltage drop, can only safely provide a maximum current of 1.25Amps for the device at the other end. Generally, PoE is able to power most IP Cameras without issue.

Picture of a PoE adapter Picture of the inside of a PoE adapter
A prototype homebrew Power-over-Ethernet receiver. Components are housed in a standard power socket block, which is robust and flame retardant. The grey capacitor damps any any in-rush current and the LED proves the receiver is powered. Power goes to the camera through the power socket on the front cover. Only the data carrying cables are connected on the Cat5e socket. The sender/injector unit is almost identical. A forward biased power diode can be added to the system to provide reverse voltage protection.


PoE Wiring Plan
 
For the those wishing to find out more about constructing a PoE sender and receiver, a Power-Over-Ethernet wiring plan can be found by clicking the PoE icon. The plan is intended for providing direct current (DC) in the range of
7 to 48 volts, at up to two amps. It also incorporates indicator LED's at both ends to indicate correct system function. The sender and receiver can be built from off-the-shelf networking components (as pictured above).

Note, this design is as-is and should be checked thoroughly before any work is undertaken. Furthermore, both operating voltage and current of the attached device should be ascertained to ensure that the load on the PoE system is within design tollerance and, the power source will be ample to drive over the required distance. 412K bytes PDF format.


Navigating cables

Installing any cable can present a challenge. Decide on the best path to navigate a cable from the router to the weather web-camera. This could be up into a loft, across and down into another room or, under a carpet and out into the garage.

Good cabling is discrete and safe. Cables should never become trip hazards, so run them along skirting boards, behind cupboards, and where major carpentry is not required, through partition walls and under floorboards. Avoid running cables in parallel contact with mains cables as this may induce interference from electrical devices into the network. When it comes to drilling holes, avoid drilling mystery walls that may contain power, water and gas services. Where cables run outside, they should be insulated an protected.

Cat-5E cable is available in short lengths and longer on economic drums. Measure the exact distance to navigate and then add ten percent; cables have a habit of shrinking twelve inches short of where they need to be! Cabling Kits are also available which often include a drum of Cat-5e, plugs, plug boots, a network switch box and sometimes, a plug crimping tool.

When threading cables through small apertures, it helps to tape over the cable end to keep the inner strands from pushing out and impeding progress. Terminate both ends of the cable with RJ45 network plugs. For a neater job, at a little more expense, an RJ45 module and patress could be mounted near to the web-camera and router instead of a bare plug. Then, only after testing the network system works, use cable ties, clips and clamps to secure the cable in place.

Picture of a wiring plan
There are many possible paths for a cable from the router to the web-camera. Typically, the longer the cable run, the greater the difficulty. There is often a distance where a non-cable solution like Ethernet-over-Power or Wi-Fi becomes a practical alternative.



RJ45 8P8C connectors

Ethernet cables are terminated with RJ45 connectors. Often termed an 8P8C connector, this means there are eight positions which are occupied by eight contacts and, it fits into a socket called a module.

When viewed end-on, RJ45 connectors are oblong.
Do not confuse this connector with it's cousin, the RJ11 connector. The RJ11 standard, also called 6P4C, is widely used to connect DSL routers to telephone lines. An RJ11 plug when viewed end-on is square-ish not oblong. The smaller 4P4C connector is used for American telephone cables.
Registerd Jack 45 versus Registerd Jack 11

See the diagram below for the RJ45 connector wiring plan. There is no need to strip the eight cables bare before they are located inside the connector. The plug contacts have teeth that bite through the insulation in a technique called insulation displacement. The contacts must be punched down firmly in order to make a reliable contact.

An RJ45 crimping tool is a worthwhile investment as it crimps all eight contracts at once. An automated cable tester is a nice-to-have accessory as it tests each conductive line at once. Should for some reason, the connector fail to make, it is often best to cut off the failed end and start again. A small bag of 8P8C connectors is a wise purchase. Never push an uncrimped connector into a module. The still proud contacts will foul the contact tangs, and prove a real nuisance to remove. That's experience talking.

Picture of a correctly assembled RJ45 plug Picture of a badly assembled RJ45 plug
A correctly assembled RJ45 connector Untwisting the cable pairs will cause the cable to lose its high speed data integrity

Although unnecessary for most inside wiring jobs, RJ45 connectors can be covered using protective boots. Available in a range of colours, boots are suitable for colour coding the otherwise grey and buff cables. When assembling ad-hoc cables, snag-less boots are preferable.

Pictured, an ordinary booted connector (top) and a snag-less boot. See how the blue boot covers the locking tab on the RJ45 connector. This prevents the tab acting like a fishing barb, snagging and then dragging on every other cable in creation.

Put boots on the cable before crimping the connectors!
Picture of a snagless boot


RJ45 8P8C connector wiring plan

Picture of an RJ45 8P8C cable wiring plan
Cat-5 cable colours and their corresponding place within the 8P8C connector. Both connectors at either end of the cable are wired in exactly the same way, making two identical looking plugs.

So is there actually a need to over-loop the solid green and solid blue coloured cables? The answer is no. In technical terms, provided the cable colour at each position on both connectors is the same, there is no need for over-looping. This is because the devices at either end have no idea of the colour of the insulation being used! Only pedantic inspectors might.

Where there is a need to make-up custom network leads, a few inexpensive tools are a worthwhile and stress-busting expenditure.

Pictured, the blue handled device is an RJ45 crimping tool.

The grey boxes are both ends of an automated cable continuity tester.

The red handled clippers are for cutting a clean edge on the Cat-5 cable so the strands will insert into the RJ45 connector without scrunching.
Picture of some network accesories


Save power and stress

Picture of a programmable power timer Employ a programmable electronic timer to conveniently switch the weather web-camera on and off throughout daylight hours. For maximum effectiveness, the timer will need adjusting as the season's progress. A programmable timer also allows a web-camera to be shut down during difficult periods of the day when an overheat is likely. An electro-mechanical timer is also suitable, provided there is not a power cut, as the timer will switch out-of-phase with the planned schedule.

A programmable timer will also solve the upload time synchronisation issue; most web-cameras upload their images relative to the time when they were powered on and not, to a 24 hour clock. If a web-camera update is required every hour on the hour, then powering up the camera just before the hour, will ensure that uploads are synchronised to the top of the hour.


Summary
  • The location of the power supply point is a critical factor with most cameras.
  • USB leads provide power but can only run to five meters.
  • If the web-camera is remote from a power supply, consider using PoE or EoP.
  • Navigate cables responsibly and never compromise on safety.
  • Invest in some inexpensive networking tools to avoid stress.
  • Always crimp RJ45 plugs before inserting them into a socket.
  • Wi-Fi cameras are not as cheap, but save on installation effort.
  • A 3G connection can save the day where there's no cables or Wi-Fi.
Mounting a weather web-camera Configuring a weather-web-camera on a network