The PPS voltage is 3.3V and tried with a resistive divider and without. I verified the pulse with an oscilloscope.
#B field vlf receiver serial
gpsd was able to detect the RES 360 SMT's default 115200 8O1 UART settings and PPS via the serial port and the PPS capability of FreeBSD's UART driver, so that means I can discipline ntpd with it. I finally got everything assembled and working. So, using low noise LDO's, I was going to build three different power supplies to ensure all grounds remained separate.ĭoes this sound unreasonable or unnecessary? Paul, what do you think? With using linear regulators, that means three different power supplies, perhaps utilizing all different windings on a power transformer.
#B field vlf receiver Pc
This would mean that the PC GPS interface needs three isolated power sources. Since the sound card ground and serial port ground share the same point, that means the serial port of the GPS module would also need to be isolated optoisolator circuits. I also wanted to use the same GPS module through the serial port of the PC so it can be used with gpsd to discipline ntpd. In the latest vlfrx-tools notes, Paul has a schematic that uses an optoisolator that isolates the PPS output so noise and ripple from the supply rail of the GPS module does not transfer to the sound card input and affect the centroid measurement.įor the GPS module interface, I wanted to use linear regulators for the power supplies of the GPS module and the soundcard input side of the PPS circuit.
The latest version of vlfrx-tools (0.9b) includes a vttime that makes it easier to use a GPS module where you can't adjust the pulse width of the PPS output, like the timing receiver modules from Trimble.
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