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!
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!