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Setting up the Si4707 WX receiver breakout board.

Got a small surprise last week, the breakout board for the Si4707 came in a few days earlier than expected so I got to play around with it over the holiday weekend. First thing I noticed, WOW that Si4707 chip is tiny! Sure the specs say it is a 3mm x 3mm package, but I don't think you get a good feeling just how small that really is until you see it. [PIC]

So after soldering on a 6 pin header so it could be inserted into the breadboard I inserted it onto one of the Proto Shields for the Arduino, and proceeded to wire it up. Five wires is all it needs, +3.3v, GND, RST, and two for communication. [PIC] Then loaded the sketch (Arduino program to run the hardware), plugged in my headphones, and tried it out. The example sketch has a serial interface so you can tune the receiver, and check other parameters, so I opened that up and tuned to my local NOAA weather frequency. The reception was lousy! The breakout board uses the headphone ground as the antenna for the receiver, and the combination of short headphone cord and poor location resulted in poor reception, ok NO reception.

A better antenna! The breakout board has provisions for an external antenna. I knew this and also ordered a BNC connector at the same time to solder onto the board. After cutting the required trace to disable the headphone antenna, and bridging the pads to enable the external antenna, I proceeded to fix the ground issue with the board. Someone else pointed it out, when you cut the trace to disable the headphone antenna you also cut the ground for the headphones, arrgh! Not a big deal, but an oversight for sure. After setting the board up, I connected a simple DIY 1/4w ground plane antenna and hung it from the bottom of the deck above my patio. (The added white wire puts the antenna length just about 1/4w for the Weather band, 162.400mHz - 162.550mHz) Still not the best, but better location, and reception is 100% better, Full quieting on one frequency, and decent on two others.

How well does it work? I had it running last night during the thunder storms in the area, and when the receiver receives the data burst for a SAME message, the SAME status on the chip changes. Using the serial monitor I was able to see the status, and message length. As soon as the receiver receives the 'End of Message' data burst, the status changes back. The sketch has no way of displaying what the actual message is, so I will have to work on that, but it is very promising.

What's next? Next step is to get the SAME message to display on the serial monitor. We are expecting afternoon thunder storms all this week, so I will have plenty of 'On Air' messages to read, if I can figure out how to extract the message from the chip.

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