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Mark Jessop darksidelemm

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View ax25_callsigns.py
#!/usr/bin/env python
#
# Print out AX25 dst/src callsigns, and packet path from a SatNOGS HexTDump
#
# Example: python ax25_callsigns.py "AE 90 64 B0 A0 9A 60 9C 6E A6 96 86 40 E1 03 F0 00"
#
import codecs
import sys
@darksidelemm
darksidelemm / 2020-11-14_FakeTLE_guide.md
Last active Nov 15, 2020
TLE Estimation for an Upcoming Rocket Launch
View 2020-11-14_FakeTLE_guide.md

TLE Estimation for an Upcoming Rocket Launch

Scenario: RocketLab are launching 30 small-sats into space in a few days. We know that one of them is going to be transmitting on the amateur radio bands, but we haven't been able to obtain a pre-launch TLE yet. We want to get setup to use strf to listen for beacon signals (see my guide here), but we need to know when to expect the satellites. We have some basic orbital information from a press release, so how can we use this to estimate a TLE for prediction purposes?

Note: I am approaching this from the point-of-view of someone who really don't know much about orbital mechanics. I'm relying heavily on the experience of others, and the content below is my attempt at documenting the process taken.

Thanks to Cees Bassa for the amazing software as always...

View spyserver_hf_aprs.sh
#/usr/bin/env bash
#
# SpyServer HF APRS iGate Script
#
# Mark Jessop <vk5qi@rfhead.net> 2020-09
#
# This script enables operation of a HF APRS iGate using input from a SpyServer.
# This is targeted for a Raspbian install. These instructions will probably work on
# other debian-based systems too.
#
View hfaprs.conf
#
# SpyServer + Direwolf configuration File
#
# Setup Direwolf to read from stdin.
ADEVICE - null
ACHANNELS 1
# Single input channel
CHANNEL 0
View gist:f09c3eb4a0fe837e4fd42347d264d85a
#!/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
View mute_button.ino
/*
Heil Dual-Switch Footswitch Momentary Mute Button
Mark Jessop < vk5qi@rfhead.net >
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:
View airspy_capture_wideband.sh
#!/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
@darksidelemm
darksidelemm / SatNOGS_RSPdx.md
Last active Sep 9, 2020
Adding SDRPlay RSPdx Support to SatNOGS
View SatNOGS_RSPdx.md

Adding SDRPlay RSPdx Support to SatNOGS

Author: Mark Jessop vk5qi@rfhead.net 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!

@darksidelemm
darksidelemm / STRF_Setup.md
Last active Feb 13, 2021
Setting up STRF Capture & Processing
View STRF_Setup.md

Setting up STRF Data Capture & Processing

Author: Mark Jessop (VK5QI) vk5qi@rfhead.net

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

View rtl_capture.sh
#!/bin/bash
# STRF Capture Script
# Mark Jessop <vk5qi@rfhead.net>
#
# 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