Radio connection to Mlb.Planet
What is a Radio connection?
Several companies produce relativly low cost radio equipment that can be
used to provide a full time internet connection to an ISP.
The most common equipment is the internal PC card that contains all of the
electronics necessary for a low power radio receiver/transmitter system.
Such cards go under the brand names of WaveLan, RangeLan, LanRover etc.
Already in New Zealand there are many ISPs using this technology to
provide short range data links from several hundred metres up to twenty
kilometers.
Software to interface to these cards exists for Linux and other popular OS
and products such as PCRoute also work to provide a complete low cost PC
based router.
Most radio connections work on a point-to-point basis with antennae at
each end aligned with each other. Some ISPs with multiple short range
radio connection have used a less directional antennae at their location
and can provide a signal to multiple customers eaach with their own
radio equipment.
Why Radio?
A radio Internet connection to Mlb.Planet has several major advantages over
other types of connection
Once a radio system is installed there are no
further ongoing communications costs - ie. no monthly rentals or time
charges. Compared to the monthly rates charged by Telecom and other Telcos
for their services this soon provides major savings in running costs.
A radio connection has much higher bandwidth (ie link speed) than other
forms of data connection. Nearly all radio equipment can sustain a throughpout
of 1Mbit/second and even with marginal signal reception this can still get
up to in excess of 256Kbits/second.
The cost of a complete WaveLan connection is about $2500, this is often
a lower cost than purchasing a router to manager a DDS link.
Radio link issues
There are also several factors that effect the suitability of a radio
link for an internet connection, these really need to be considered and
possible problems resolved before proceeding.
The most important issue is that there should be line-of-sight between
both ends of the radio link. This is the ideal situation.
Even when this is not exactly the case there may still be a good chance that
a radio link will operate successfully. Every situation is different and
often the only way to know that a radio will not work is to try a test
connection.
The distance between the radio nodes. The shorter the range then the
stronger the radio signal and hence the higher the throughput on the link.
The antennae used at each end of the link also determne the signal gain
and hence the range limits of the radio signal. The higher gain type antennae
(about 26db gain) will often work out to a range of 8 to 10 Kilometers. For
shorter range there are lower cost antennae based on the Yagi design that
allow a greater signal spread so that multiple connections are possible. In
this case the range becomes quite small, often less than a kilometer.
Connecting to a LAN. Most often the location of the radio link antennae
will be some distance away form the computer equipment. This can be a
problem in that the RF cable connecting the radio controller (in a PC) to
the antennae needs to be kept as short as possible, 5 metres or less.
Longer cables will seriously reduce the signal strength even to a point
where the signal may be totally lost.
This cable restriction often means that the PC containing the Radio
controller needs to be physically located in a roofspace or at some
inconvenient location near the antennae. This PC will then need to have
access to power and have a network connection. The tradeoff here is
installing a longer network cable to the PC versus a shorter RF cable to
the antennae. The closer the radio controller (PC) is the the antennae then
the better quality radio signal is obtained.
A typical WaveLan 26db gain antennae located on a
suitable roof corner to provide line-of-sight to
another identical antennae several kilometers
distant.
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Page owner: <dgd@mlb.planet.gen.nz>
Last modified: 24 March 1998.