A Microcontroller Operated SWR Meter: Unterschied zwischen den Versionen

Version vom 13. September 2009, 03:33 Uhr

1 Project description

This project is part of the SVXLink project. Since I intend to use T7F transceivers for this project, it is highly interesting to detect troublesome antenna and SWR conditions and to be able to shut off the transmitter. The only way to do that is to read out the SWR digitally. And this can be done using the I2C BUS.

BTW, I want to measure some more values:

• PA temperature
• Transmitter power consumption / input current
• Total system input current

And I want to switch some things, too:

• Be able to switch the transceiver OFF

But very basically this project can also be seen in an isolated perspective: I want to learn how to use a microcontroller and set up a project that's usefl for other OMs as well.

2 Other People's work

• http://www.dj4uf.de/projekt/swr/swr.htm - cool idea for a simple directional coupler. I see that a Aircell cable is perfectly suited for this job.
• http://accrochages.drone.ws/en/node/125 - a voltage meter project based on the Arduino
• http://www.foxdelta.com/products/swr-hf.htm <- There you can buy pre-assembled kits, but that's not what I want.
  • http://www.electronics-lab.com/blog/?p=2092
  • http://www.youritronics.com/100w-vhf-uhf-lcd-pic16f88-swr-meter/

3 Project Plan

• First build a directional coupler. Role model: http://www.dj4uf.de/projekt/swr/swr.htm
• Then make sure the readouts of the forward voltages are within a reasonable range. identify peak voltages.
• Then take the BeagleBoard and be successful measuring voltages through a Analog Digital Converter (ADC).
• Then connect the coupler to the ADC and see if it's possible to measure the voltages.
• Then connect an LCD display to an Arduino board.
• Then successfully control the LCD display and devise a reasonable display readout
• Then read the I2C bus from the Arduino board
• Then calculate the SWR based on the readings from the I2C bus and send them to the LCD display
• Finally build a nice case
• Write an article and post it in some fancy electronics magazine :-)

4 Progress

• 2009-09-04 The BeagleBoard has an I2C header in the expansion port. So it is just a wonderful idea to use it and read out some things. The only problem: It's operated with 1,8V. So I need a bidirectional voltage translator.
  • I found one across the Atlantic at Ebay: Gravitech has such a thing for a decent price: http://gravitech.us/MicroResearch/I2C/I2C-TRN/I2C-TRN-Manual.pdf
  • Another option would be to built it by myself using the PCA9306: http://focus.ti.com/docs/prod/folders/print/pca9306.html
• 2009-09-05 I decided to get the one from Gravitech.
• 2009-09-10 My ADC arrived. I'm still waiting to receive the voltage translator. And I have bought some books on Arduino programming. Still need to buy the Arduino board and an LCD display.
• Come back and see in a few weeks / months...