In the previous post we looked at how to receive GPS spread spectrum signals using an RTL_SDR V3 with a patch antenna (Ref.1, Ref.2). In this post we will see how to send the RTKNAVI data to OpenCPN so that we can plot our position on a nautical chart.
RTKNAVI Output Stream Setup
Figure 1 shows the input and output signal flow to RTKNAVI taken from the manual (Ref.3/p8). We setup the input stream in the previous post, now we are going to configure the output stream. Open rtknavi, and in the top right hand corner select O for output. Configure the output as shown in Figure 2 for TCP Server, 127.0.0.1_port 2947, NEMA0183. Now in OpenCPN add a TCP connection as shown in Figure 3.
Once you have configured rtknavi and OpenCPN for TCP Server/Client, go through the same procedure for reception as we did in the previous post. Figure 4 shows the rtknavi satellite fix, Figure 5 shows the GPS location on OpenCPN (red boat), FIgure 7 is an iPhone GPS fix for comparison and Figure 8 is the YouTube video explanation.
Please send your comments, questions and suggestions to:
#1. – “RTL-SDR for Satellite GPS”
#2. – “RTL-SDR GPS Decoding Tutorial”
#7. – “RTKLIB Manual”