GNU Radio

GNU Radio is a free & open-source software development toolkit that provides signal processing blocks to implement software radios. (HackRF, BladeRF, USRP, RTL-SDR)

Gqrx SDR

Gqrx is an open source software defined radio receiver (SDR) Airspy, Funcube Dongles, rtl-sdr, HackRF and USRP devices

SigintOS

SigintOS as the name suggests, SIGINT is an improved Linux distribution for Signal Intelligence. (HackRF, BladeRF, USRP, RTL-SDR)

URH

Universal Radio Hacker (URH) is a complete suite for wireless protocol investigation with native support for many common Software Defined Radios

Kismet

Kismet is a wireless network and device detector, sniffer, wardriving tool, and WIDS (wireless intrusion detection) framework

Gps-sdr-sim

Software-Defined GPS Signal Simulator

SDRSharp

SDR software for Airspy and RTL-SDR dongles and HackRF/AirSpy/USRP! The best Windows SDR software out there

SigDigger

Qt-based digital signal analyzer, using Suscan core and Sigutils DSP library for hackrf and other sdr-rtl dongles

Gqrx-scanner

A frequency scanner for Gqrx Software Defined Radio receiver. Scan ranges, bookmarks, filter on tags as well. Very handy tool to remote control your gqrx software.

FCC Freq Alloc

FCC Online table of Frequency Allocations. This is a PDF. HAndy way to see whats allocated to what in the USA. Only gives an idea of the range not the direct frequency.

Radio Spectrum

The radio spectrum is the part of the electromagnetic spectrum with frequencies from 30 Hz to 300 GHz. (Wiki page/link)

DKScan

Danish frequencies for all known services and bands. This might be outdated and also TXT document. You can refer to their site, this is just a backup. www.dkscan.dk