I’ve done some more programming on the openASC project. Mainly been doing stuff to get the communication protocol more stable but also implemented some other functions. I have started to make the powermeter sensors compatible with the openASC manouver box, making it possible to have the openASC box to listen for a powermeter with a certain ID. That way if the VSWR is too high we can shut down the option to PTT the radio, hence hopefully saving some equipment from burning up.
I also did some hardcore tests on the bus. A while ago I simulated the filtering for the bus and decided to decrease the communication speed down to 57600 baud instead of 115200, hence getting a few more dB of attenuation from the ham radio frequencies. To test this I took a signal generator which I set to maximum output, which gave 2.5v peak to peak voltage on the bus at 1.8 MHz. To do this you need to insert 100mA into the bus, since it’s terminated with 50 ohms at each end. The actual communication over the bus is run at a current of 120mA, giving a peak voltage of approximately 3V. When measuring after all filtering I could barely see any ripple of the 1.8 MHz signal from the signal generator and when going up in frequency it was very little which could be seen and nothing that will have any effect on the communication. So hopefully this means the bus is very solid against RFI.
Next week I will hopefully get a manual pick & place machine at work, which will help me to assemble the rest of the boards. So hopefully I’ll soon have a few more boxes to test with and we are getting closer installing the system at the station, which will be a blast (hopefully).
