Propagation Testing with GNSS on OpenStreetMap – Telecommunications, Navigation & Electronics

Introduction

In the previous post I did a walkabout to test the propagation testing equipment on OpenStreetMap (Ref.1). In this post I do the same thing but actually drive over a greater portion of the map area. For reference purposes I use Toronto Marine Weather at 162.4MHz as the test signal.

Equipment Block Diagram

Fig.2 Equipment for Drive Test Inside Car

Figure 1 shows the equipment block diagram. For reception, I use a VHF whip with magnetic base that conveniently mounts on the car roof with a lead in long enough to reach the spec analyzer on the front seat. The GNSS receiver has a magnetic base as well and sits next to the VHF antenna. Since the spectrum analyzer will take usb power from the laptop, a portable lithium battery/inverter feeds the laptop power supply in order to operate over several hours. Figure 2 shows the equipment inside the car.

Drive Test Results

Fig.3 OpenStreetMap Selection of Toronto Including the Harbourfront

Fig.4 Signal Capture Screen Set for GPS delta=10m

Figure 3 shows the OpenStreetMap used on the previous post and in this one. The coordinates were entered into the spectrum analyzer software and saved as a session. Figure 4 shows the propagation results consisting of saved power levels/lat_long/alt for every gps delta of 10m. The drive path in the centre of the map was relatively short approx 25Km due to heavy traffic. Power levels varied from dark blue to light green -90dBm to -60dBm.