Monday, 21 April 2014

Update on the WSPR Ultimate 3 kit

I thought i would share a quick update on my WSPR experiments at home. My initial setup of the WSPR included what I though was quite a healthy heartbeat from the GPS module. In fact this was incorrect, i had the Serial Data and PPS lines crossed and the U3 thought the Data was the PPS signal. hence why the recalibration sent the Reference oscillator wildly off course.

Now fixed, i don't have a heartbeat coming from the module, but thats because the GPS module is too close to the U3 and also there is a lack of pull up resistors between the 3.3v and TX pins. both these issues I will fix this week

Another point and is based upon many questions i am getting about the module is what antenna am I running. Well its simple Im using my main shack antenna - this being the MQ26-SR. With the calculated output of the WSPR module(288mW) and the ERP figures of the antenna (6dB), the grand ERP will be about 1.1W-ERP

This 1.1W ERP would account for how well the little module is doing. I have since corrected the DDS instability, by adding a heatSink, only the clock update and calibration need sorting - these both will be corrected when I sort out the GPS module.

This map shows a 8 hour transmission period, transmitting once every 4 minutes. No calibration is done as the GPS module is disconnected. I manually set the Reference oscillator by transmitting a 14Mhz signal and measuring the output on the Oscilloscope. I made the change to the oscillator by making adding the difference to the Ref. Oscillator of how much it was off by. (in my case just 163Hz)

Anyway here is a quick tour around the unit. This video was taken and made before I realised i had the GPS wired up wrong, and before I corrected the instability of the DDS module.