Mark Jessop darksidelemm

Adding SDRPlay RSPdx Support to SatNOGS

Author: Mark Jessop [email protected] Date: 2020-05-08

The SDRPlay RSPdx is a pretty new SDR, and as such is only supported in the SDRPlay v3 API. The current pothosware of SoapySDRPlay only supports v2 of the API, so we need to use a different fork for now.

Note that the v3 API is in beta, and users of older model SDRPlay units may have better luck using the v2 API.

This guide assumes you are starting from an updated SatNOGS RPi image. I have only tested my RSPdx with a few observation so far, so there may be bugs!

Setting up STRF Data Capture & Processing

Author: Mark Jessop (VK5QI) [email protected]

This guide provides information on how to capture FFT data using the strf toolset, process it to look for satellite signals, and finally compare their doppler shift against TLEs from the SpaceTrack database. This can help with resolving the 'TLE lottery' after new launches, or cataloguing transmissions from spacecraft already in orbit.

It should be noted that the analysis described in this document is but a small subset of what the strf tools are capable of! Scott Tilley has a post describing some of the history behind strf and giving a crash course on the relationship between orbital dynamics and the doppler effect here: https://skyriddles.wordpress.com/2019/01/04/basic-orbital-dynamics/

The target platform is Debian-based distributions (e.g. Debian, Raspbian, Ubuntu), but should be applicable to other Linux-based platforms. The data processing software (rfplot and rffit) is also k

Decoding FSK9k6 transmissions from SatNOGS observations using Direwolf

Dependencies

Direwolf - https://github.com/wb2osz/direwolf
sox
wget

Setup

Create a file called ax25_9600.conf with the following contents

	#
	# SpyServer + Direwolf configuration File
	#

	# Setup Direwolf to read from stdin.
	ADEVICE - null
	ACHANNELS 1

	# Single input channel
	CHANNEL 0

	#!/bin/bash
	#
	# WIA Broadcast - FreeDV Encoder Cron Job
	#
	# To be run ~2AM Sunday Morning, to be sure all the required files are in place...
	#
	# Requirements:
	# - freedv_tx and required libs should be in this directory.
	# - ffmpeg (available with apt-get, or macports, or homebrew or whatever)
	# - wget

	/*
	Heil Dual-Switch Footswitch Momentary Mute Button

	Mark Jessop < [email protected] >

	Mutes system audio on Windows machine when a footswitch is pressed, then un-mutes when
	the switch is released. This is useful when listening via a remote SDR on a PC, which
	can also hear your own transmissions (helps avoid echo!)

	Hardware:

	#!/bin/bash
	# STRF Cronjob Script
	#
	# Compile rffft from https://github.com/cbassa/strf
	# Use: make rffft
	# You should only need libfftw3-dev as a dependency.
	#
	# Prepare directory with:
	# mkfifo fifo
	# mkdir data

	#!/bin/bash
	# STRF Capture Script
	# Mark Jessop <[email protected]>
	#
	# Compile rffft from https://github.com/cbassa/strf
	# Use: make rffft
	# You should only need libfftw3-dev as a dependency.
	#
	# Prepare directory with:
	# mkfifo fifo

	Sonde Type Count Percentage

	AVK - AK2-02 (Russia): 6 0.8
	AVK-BAR (Russia): 15 1.9
	AVK-MRZ (Russia): 8 1.0
	Beijing Changfeng CF-06 (China): 2 0.3
	GTS-1 (China): 82 10.6
	Graw DFM-06: 1 0.1
	Graw DFM-09: 46 6.0
	Intermet iMet-1-AB: 5 0.6

	#!/usr/bin/env python
	import crcmod


	def check_crc(data, crc):
	crc16 = crcmod.predefined.mkCrcFun('crc-ccitt-false')

	_crc = crc16(data)

	# Convert incoming CRC to a int