erikson1970

GNU Radio in M1 Macs (with Docker Desktop)

This note describes the steps we took with the SETI Institute summer interns 2021 to install GNU Radio in their M1 Macs (MacBook Air M1 2020 model). We used gnuradio-docker-env as a starting point, which was of invaluable help.

There might be omissions, typos, etc., in this note, so any feedback is welcome. The procedure could also be streamlined a lot by generating known-good images and pushing the to Docker Hub.

XQuartz

DigitalOcean does not provide a way to download a snapshot of your droplet locally. You can use rsync to accomplish this instead.

On your local machine, assuming you have added your-server in your SSH config:

rsync -aAXHv --append-verify --exclude={"/dev/*","/proc/*","/sys/*","/tmp/*","/run/*","/mnt/*","/media/*","/lost+found"} your-server:/

-a : archive mode (all files, with permissions, etc.)
-A : preserve ACLs/permissions (not included with -a)

LTE-Cell-Scanner under Raspbian (and maybe Ubuntu/Debian)

Mark Jessop [email protected] 2017-11-19

Here in VK-land, GSM is dying, if not already dead in many parts of the country. As such, RTLSDR calibration tools like kalibrate-rtl are not particularly helpful! However, thanks (mainly) to Telstra, we have a very wide coverage 4G (LTE) network on 'Band 28', which is in a good frequency range for use with a RTLSDR (Downlink band 758 – 803 MHz). LTE-Cell-Scanner provides the 'CellSearch' utility, which will search for LTE cells, and determine the RTLSDR's clock offset. This gist attempt to provide some sort of guide on getting CellSearch running under Raspbian.

1. Copy m3u8 link

2. Run command

echo "Enter m3u8 link:";read link;echo "Enter output filename:";read filename;ffmpeg -i "$link" -bsf:a aac_adtstoasc -vcodec copy -c copy -crf 50 $filename.mp4

Simple Security Guidelines

Using an iDevice? (Best option)

Use an iPod or an iPad without a SIM card
Use an iPhone
Do not jailbreak
Always upgrade to new iOS versions
Use Brave browser

Need Secure chat?

Operational PGP

This is a guide on how to email securely.

There are many guides on how to install and use PGP to encrypt email. This is not one of them. This is a guide on secure communication using email with PGP encryption. If you are not familiar with PGP, please read another guide first. If you are comfortable using PGP to encrypt and decrypt emails, this guide will raise your security to the next level.

tmux shortcuts & cheatsheet

start new:

tmux

start new with session name:

tmux new -s myname

	#!/usr/bin/env python

	import threading
	import time
	import RPi.GPIO as GPIO

	GPIO.setmode(GPIO.BOARD)

	# GPIO pins

	# When you're sure of the format, it's much quicker to explicitly convert your dates than use `parse_dates`
	# Makes sense; was just surprised by the time difference.
	import pandas as pd
	from datetime import datetime
	to_datetime = lambda d: datetime.strptime(d, '%m/%d/%Y %H:%M')

	%time trips = pd.read_csv('data/divvy/Divvy_Trips_2013.csv', parse_dates=['starttime', 'stoptime'])
	# CPU times: user 1min 29s, sys: 331 ms, total: 1min 29s
	# Wall time: 1min 30s

	using System;
	using System.Diagnostics;
	using static System.Math;

	// Some helpers for converting GPS readings from the WGS84 geodetic system to a local North-East-Up cartesian axis.

	// The implementation here is according to the paper:
	// "Conversion of Geodetic coordinates to the Local Tangent Plane" Version 2.01.
	// "The basic reference for this paper is J.Farrell & M.Barth 'The Global Positioning System & Inertial Navigation'"
	// Also helpful is Wikipedia: http://en.wikipedia.org/wiki/Geodetic_datum