RF Bridge for data recording

Wireless & IoT
1

I am looking to build a wireless data recording device that uses a DAQ board and a serial input to the computer. Right now, the system works just fine wired and plugged in to a standard USB 2.0 port. What I want to do is wirelessly bridge the sensor to the computer from a couple hundred feet away (hence the reason to try to remove wires).

From sparkfun.com I have looked at a few products that look promising:

Transmitter:

Power:

Polymer Lithium Battery (1 for each DAQ/sensor)

http://www.sparkfun.com/commerce/produc … ts_id=8483

5V DC to DC Step Up - VPack PCB

http://www.sparkfun.com/commerce/produc … ts_id=8290

With this setup I estimated that I could get 5V at 300mA for 4 hours. Correct me if I am wrong. The goal of this is to power a DAQ board and sensor through a USB connection as well as power the RF transmitter.

RF Transmitter:

RF Link Transmitter - 434MHz

http://www.sparkfun.com/commerce/produc … ts_id=8946

ProtoBoard - Square 2"

http://www.sparkfun.com/commerce/produc … ts_id=8811

The DAQ will connect to the transmitter through a standard Female USB connector.

Receiver:

This will be powered through a computer’s (Laptop) USB port.

RF Link 4800bps Receiver - 434MHz

http://www.sparkfun.com/commerce/produc … ts_id=8950

Proto Breadboard - Rectangle Wired 3"

http://www.sparkfun.com/commerce/produc … ts_id=8812

The intended use of this is merely wirelessly bridge a gap between a single sensor and the computer that will be recording data.

Any help would be helpful (i.e. If this setup is feasible).

If this is not feasible, are there any better methods you would recommend?

Thanks

2

Those little RF-Link transmitter / receivers are inexpensive, but can be difficult to get working reliably. They simply modulate the RF carrier with the input signal, so in general they aren’t suited for transmitting async serial from one point to another.

Take a look at our radio module comparison and tutorial: http://www.sparkfun.com/commerce/tutori … als_id=128

My first thought would be Bluetooth, which is simple to get working using one of our modules, and doesn’t require extra hardware on the PC side (if you already have Bluetooth built into your PC). Unfortunately your range is a bit farther than I’d trust Bluetooth to work over.

I’d suggest looking at our XBee modules, which have a whole RF protocol built into them designed to send serial data from one point to another. We carry a whole range of modules with various power and antenna options, so you should find something that will work for your distance.

Hope this helps, any other thoughts?

3

XBees (series 1 anyway) also have firmware to read Input port digital bits and recreate them on a distant XBee as outputs. And vice-versa.

Virtual wire, they call it.

4

You will be FAR happier with the XBee modules. A pair of Series 1 modules will fill the bill perfectly.