Cheap 433 Mhz Serial TX & RX - Which ones!

[Kevin Walton]

Hi All

I'm looking for a pair of cheap 433 Mhz Serial TX & RX modules to send
GPS information from a model airplane back to a laptop on the ground.
It's the first time I hzve played with these modules and I'm just
overwelmed by the level of information and choices around.

I need a 4800 baud data rate for the GPS and I'd like to feed Serial
directly in and get Serial directly out, but can do some work on
Veroboard for level changers or encoders etc if I need to.

The Renton LC-434 modules:

http://www.rentron.com/PicBasic/RemoteControl.htm

look quite good, but are in the US and quite expensive (40 USD plus
shipping for the pair).

Most of the options on http://www.rfsolutions.co.uk/ in the uk that I
can find avaliable don't talk about serial options.

What can I buy from RS, Maplins, Farnell or another supplier to do the
job simply and cheaply for me (25 USD, 25 pounds type level)?

Sorry for the simple question but I'm a bit overwelmed with all the
options right now and supprsingly can't find anyone who has done
exactly htis before on the web!

Cheers
Kev

 

[Vladimir Vassilevsky]

I'm looking for a pair of cheap 433 Mhz Serial TX & RX modules to send
GPS information from a model airplane back to a laptop on the ground.

I have just accomplished the similar project.

It's the first time I hzve played with these modules and I'm just
overwelmed by the level of information and choices around.

The important consideration is the need for licensing in the different
countries.
The operating distance should be 2..3km at least. That means you can't
go with a garage opener transmitter or Bluetooth device.

I need a 4800 baud data rate for the GPS and I'd like to feed Serial
directly in and get Serial directly out,

RS232 over wireless is definitely not the best choice. It is very error
prone and unreliable. 4800 bps is too slow if you are looking for GPS
updates every second.
I used packetized PSK transmission with FEC.

The Renton LC-434 modules:

Consider Aerocomm modules.

Sorry for the simple question but I'm a bit overwelmed with all the
options right now and supprsingly can't find anyone who has done
exactly htis before on the web!

Here I am.

Vladimir Vassilevsky

DSP and Mixed Signal Design Consultant

http://www.abvolt.com

 

[Tim Auton]

I'm looking for a pair of cheap 433 Mhz Serial TX & RX modules to send
GPS information from a model airplane back to a laptop on the ground.
It's the first time I hzve played with these modules and I'm just
overwelmed by the level of information and choices around.

I need a 4800 baud data rate for the GPS and I'd like to feed Serial
directly in and get Serial directly out, but can do some work on
Veroboard for level changers or encoders etc if I need to.

Most of the options on http://www.rfsolutions.co.uk/ in the uk that I
can find avaliable don't talk about serial options.

What about their "Low cost FM transceiver", 2-way (which you don't
need) but it takes serial logic levels and does all the buffering,
encoding, decoding etc. for you. £34 a pair.

What can I buy from RS, Maplins, Farnell or another supplier to do the
job simply and cheaply for me (25 USD, 25 pounds type level)?

Have you looked at Rapid Electronics? You can download the "Security &
Warning Devices" bit of their catalogue as a PDF from

www.rapidelectronics.co.uk

They supply RF Solutions stuff as well as LPRS "Easy Radio" modules, a
pair of "Easy Radio FM transmitter and receiver" would set you back
just under £30. They also do all the encoding/decoding business for
you. I've used Rapid Electronics before and they live up to their
name. They also sell enconding/decoding chips and the like (and of
course the full range of the rest of the electronics gubbins you could
ever want).

I don't know how much range you want, you'll not get a whole lot for
£25 (200m or so with small omnidirectional whips) and you should look
at the licensing requirements to see how much transmit power you are
allowed. You could use a directional receive antenna for more gain
and/or be naughty and overpower a transmitter a bit and use something
other than the 1/4 wave whip transmit they are approved for. That
would of course be illegal, but I doubt anybody would even notice in
the wide-open spaces you need to fly a plane.


Tim

 

[Tim Auton]

Sorry to follow myself up, but if by "serial" you mean RS232 then
something like a MAX232 would do you for the Rx logic level > PC RS232
interface.


Tim

 

[Kevin Walton]

Hi All

Thaks for the info, google seems to have lost my first reply so I'll
go over it again here.

Yes Serial = RS232, 4800 baud ASCII (NMEA) out of the GPS, into a
laptop, as though they are directly connected.

Distance wise, 200m quoted ground to ground should give me a fair bit
more for air to ground I think and 400m should be enough. In remote
locations I'm happy to play with a little more power and different
aerials

Will have a look at the specific recomended solutions.

Cheers
Kev

 

[Kevin Walton]

Hi all

An "Easy Radio FM transmitter and receiver" on it's way to me....

http://www.lprs.co.uk/main/product.info.php?productid=152

Will let you know how it goes

Cheers
Kev

 

[Luhan Monat]

I'm looking for a pair of cheap 433 Mhz Serial TX & RX modules to send
GPS information from a model airplane back to a laptop on the ground.
It's the first time I hzve played with these modules and I'm just
overwelmed by the level of information and choices around.

Try these, there cheap. $4 transmitter, $5 receiver.

http://www.mouser.com/index.cfm?han...uctid=446416&e_categoryid=132&e_pcodeid=50900
RCR-433-RP Radiotronix Embedded Wireless Modules Distributor - Mouser
Electronics - Electronic Component Distributor

 

[Randy Ott]

Kev,

I would suggest you take a look at local regulations. For example, in the
US, FCC regulations put a limit on the duty cycle of these 425-435 MHz
transmitters. This makes them useful only for remote control. The cheap
ones use OOK modulation which would be difficult to use with an NRZ data
stream.

There are some transmitter/receiver modules available as a "wire
replacement" but they are not so cheap.

You can see an example at www.radiotronix.com

Randy Ott

 

[Vladimir Vassilevsky]

Try these, there cheap. $4 transmitter, $5 receiver.

http://www.mouser.com/index.cfm?han...uctid=446416&e_categoryid=132&e_pcodeid=50900
RCR-433-RP Radiotronix Embedded Wireless Modules Distributor - Mouser
Electronics - Electronic Component Distributor

Radiotronix is not going to work for model airplane. The operable
distance of their modules is about 100m max. Also, you have to apply for
license.

The good transmitters for a few km range are build by Aerocomm,
DataRadio.

Vladimir Vassilevsky

DSP and Mixed Signal Design Consultant

http://www.abvolt.com