- PIPE SDRSHARP IN TO WXTOIMG UPDATE
- PIPE SDRSHARP IN TO WXTOIMG DRIVER
- PIPE SDRSHARP IN TO WXTOIMG SOFTWARE
We used autorun.sh to schedule the satellite and start the interface. We also used autosat.py to call receive_and_process_satellite.sh when satellite passing our head. As for the interface, we developed the autosat.py with pygame to show the satellites pass events and images received.
PIPE SDRSHARP IN TO WXTOIMG SOFTWARE
This is the low level software of our Raspberry Pi. Then, we impelemented the receive_and_process_satellite.sh, which received the signal from satellites and process it into a wav file. We also implemented schedule_satellite.sh to calculate each pass event and store the information into atqlog.sat and goodluck.sat, two files that contains the information of each pass event.
PIPE SDRSHARP IN TO WXTOIMG UPDATE
The first script we implemented is schedule_all.sh, it update satellite information from celestrak and creates a TLE file for prediction use. After all the software installation process, we implemented scripts to schedule the satellite signal receiving. In addition, we installed the wxtoimg for audio decoding and weather map generation. To know when the satellites pass overhead, we installed predict software. We also installed the sox audio toolkit for post processing the audio stream from satellite.
PIPE SDRSHARP IN TO WXTOIMG DRIVER
First of all, the driver for the RTL dongle has been installed to raspberry pi. In this section, I will discuss the software we implemented for this project. The picture above on the right is our QFH antenna. Later that evening, we did an initial test since there's a satellite pass-by at 10:30pm. In the process, we cut the additional PVC pipe, sticked the 3D printed parts to PVC pipes, measured dimensions, soldered wires, and put it all together. 23, 2019, we met at the ECE Maker Club 3pm in the afternoon and worked on building the antenna. On Thursday, we did some initial build by cutting the PVC pipes and then went to Home Depot again for purchasing additional PVC pipe. The next day, we picked up those printed parts and headed to the Home Depot for buying suitable pipes and coax cable. This included the parts for the top, middle, and bottom mounting brackets. 18, 2019, I sent the custom-made STL files to the Rapid Prototype Lab for 3D printing. We finally settled down with building the QFH Antenna because of the its easy-to-build characteristics and that beautiful helix shape. On Nov. Based on the calculation, we need to design the antenna with the following dimension (Picture below on the left) This antenna is omni-directional and we don’t need to move it based on the location of satellites. Unlike previous two styles, Quadrifilar Helix (QFH) antenna contains a single wire that wound in the form of a helix.This antenna style has a safety concern: every dipole is sharp-pointed to outside.
Each of the four dipole supports is tilted 30 degrees from vertical. Each dipole should have length of 38.25 inches and 21.5 inches spacing. Double cross antenna contains four dipoles.We also have to move the antenna direction based on the location of satellites. To receive signals from NOAA, we need to set two dipoles with leg length 53.4cm and spread apart 120 degrees. It is based on a very simple linearly polarized dipole. V-dipole antenna is the most trivial antenna during the construction.
In the beginning, we did some research and considered three different kinds of antenna for receiving signals from NOAA satellites: V-dipole Antenna, Double Cross Antenna and QFH (Quadrifiliar Helix) Antenna. The figure below shows the components of our design. The tools we used are Raspberry Pi, piTFT touchscreen, SDR USB dongle and satellite signal receiving (QFH) antenna. The final outcome of this program is to process/decode the weather images and display them on the touchscreen as they become ready. This system is capable of displaying the time remaining for the next satellite overhead event and recording the signals autonomously for decoding. In specific, we were trying to develop and test a design for incorporating this SDR dongle into the Raspberry Pi ecosystem and developing a nice yet simple graphical interface for receiving the live weather image from the NOAA satellites. Thererfore, we wanted to do some experiments with it. Because of that, it can be applied to receive signals from FM radios, HAM communications, and even satellite signals. We found it very interesting because it has a very broad range of frequency detections and leaves all the filtering & processing stuff to the software.
In the beginning of the autumn semester, we came across some videos from Youtube introducing the SDR (Software Defined Radio).