44 Silicon chip Australia’s electronics magazine siliconchip.com.au
433MHz Wireless Data
Range Extender
by John Clarke
There are many “remote control” devices
which rely on a 433MHz data link. You may
have one and not even realise it – an alarm
remote, a garage door/gate controller or even
an outdoor weather station are just some examples.
But is yours 100% reliable? Is the range a bit less
than you’d like? Perhaps the remote unit is
too far away from the receiver – or are there hills,
trees or other obstacles in the way?
Here’s the answer: a small, solar-powered repeater
that you place between the transmitter and receiver
with clear line-of-sight to both. You’ll end up with
the reliability – and the extra range – you need.T
here are quite a
few devices which
transmit periodic
bursts of data on the 433MHz UHF
“LIPD” band, including a number of
our designs, such our Driveway Moni-
tor (July & August 2015; siliconchip.
com.au/Series/288).
This includes some commercial
devices too, such as remote weather
stations. Unfortunately, it isn’t always
possible to get reli-
able reception.
Sometimes this
is because there are
hills, trees, build-
ings etc between
the transmitter and
receiver locations.
Other times, it’s
because of limit-
ed antenna sizes
or the 25mW le-
gal limit placed on
unlicensed devices operating in this
band (many 433MHz transmitters are
far weaker than this).
Even the weather can have an im-
pact: a shrub or tree that has little to no
effect in dry weather can play havoc
with UHF signals in the wet.
While 433MHz signals aren’t atten-
uated as much as higher frequencies
(eg, 2.4GHz, which is also used for
data), if you’re suffering from marginalsignal anyway, it could be enough to
stop data getting through.
This repeater can be placed in a lo-
cation where it can clearly and reliably
receive signals from the transmitter,
and which is also a better location for
reception by the receiving unit (ie, it
can be placed somewhere in between
the two devices).
It stores the received data and then,
after a short delay, re-transmits the
same signal in the same
frequency band.
So this design is suit-
able for extending the
wireless range by up to
two times, where line-
of-sight transmission is
possible.
But it’s also extremely
effective at improving the
signal integrity where the
two units have obstruc-
tions between them, in-Features
* Extends the range of 433MHz transmitters
* Overcomes ‘line-of-sight’ limitations caused by trees, obstacles etc
* Receives 433MHz signal and re-transmits at 433MHz after a short delay
* Suitable for use with projects that transmit intermittent signal bursts
* Discrimination of genuine signal from noise
* Repeater chaining possible
* Adjustable delay period
* Adjustable maximum data rate detection
* Solar power with LiFePO 4 cell storage
* Up to 200m open-space range with optimised antenna