radio signal intelligence (SigInt)

Introduction

this page is about developing abilities to better understand radio transmission sources, especially if you are paranoid!
for example, using a spectrum analyzer can:
- show if a criminal is using a radio jammer in your vicinity
  - these are illegal in Australia and could be used to prevent potential victims from calling on their mobile phones, or jamming GPS signals, etc
  - a jamming device would show up as all frequencies having a lot of noise
- detect where a radio transmission is coming from
  - requires a bit of triangulation and a directional antenna such as the null direction of a loop antenna, dial in the frequency of the transmission and set zero span on to keep this narrow, then look for the position where the signal drops out
    - log periodic and yadi antennas are too broad for this use
    - its helpful if the spectrum analyzer has a sound feature which increases pitch as the signal strength increases
- display a range of radio wave activity according to frequency

whilst you could use a software defined radio (SDR) receivers and a tablet or laptop, you really need a portable spectrum analyzer with a wide frequency range so you can take it out on location and have the extended frequency range to detect WiFi and Bluetooth, etc which basic SDRs may not detect
many WiFi Routers can allow software to display a spectrum of WiFi signals and their relative strengths - but these have a limited frequency range usually restricted to the WiFi frequencies

TinySA Ultra
HackRF Portapack
- this is not only a spectrum analyzer but a versatile SDR transceiver with extended frequency range
- see transceivers - software defined radio (SDR)
- https://www.youtube.com/watch?v=n7N7G_9tj9w

NB. indoor environments can be complex, with materials like concrete and metal affecting RF propagation and making locating more difficult
KrakenSDR
- https://www.youtube.com/watch?v=y9YkFZDCyeo&t=11s
smartphone apps
- these use the antenna in your smartphone to help you locate an RF transmitter
RF Detectors
- these are generally basic devices which emit a sound or visual alert to indicate RF signal strength - some allow selecting certain types of RF eg. WiFi vs Bluetooth vs 4G/5G
- more advanced devices:
  - ThinkRF devices for indoor geolocation

hackers can use devices such as FlipperZero to not only create a WiFi hotspot but can configure it to open a bogus web page which looks like the real thing
- when a user logs onto that WiFi, their browser will automatically open to the bogus web page and this could look like a real online service log on page - but logging on will only send their log on details back to the hacker's device - it won't actually do anything else on the browser
- see https://www.youtube.com/watch?v=3Kr_3OZHy_g
- the hacker could already have checked the WiFi name that a person is usually logging into, and then re-use that name for their bogus hotspot but by sending a more powerful WiFi signal, it may trick their phone to connect to the hacker's WiFi server

transceivers - software defined radio (SDR) such as FlipperZero or HackRF Portapack can record radio transmissions from your remote control and play them back to unlock your car or your roller door IF the technology for these is of the older type which allows this
- most cars made after 2014 apparently have improved remotes which are not so easily hacked