RTL-SDR for Satellite GPS on OpenCPN


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

Fig.1 RTKNAVI Input & Output Streams
Fig.2 RTKNAVI Output Stream Configuration
Fig.3 OpenCPN Connection

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, 2947, NEMA0183. Now in OpenCPN add a TCP connection as shown in Figure 3.

Fig.4 RTKNAVI GPS Satellite Fix
Fig.5 OpenCPN GPS Position
Fig.7 iPhone Fix for Comparison

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.

Fig.8 YouTube Video RTL-SDR for Satellite GPS on OpenCPN

Please send your comments, questions and suggestions to:

YouTube Channel
YouTube Channel


#1. – “RTL-SDR for Satellite GPS”

#2. – “RTL-SDR GPS Decoding Tutorial”

#7. – “RTKLIB Manual”

By Jeremy Clark

Jeremy Clark is a Senior Telecommunications Engineer and Advanced Amateur Radio Operator VE3PKC. He is the author of E-Books on Telecommunications, Navigation & Electronics.