FM signals/strenghts

Ambient, baseline signal strength

Though transmitted signal strengths drop off increasingly rapidly (exponentially) from a single source, powerfully transmitted signals can be broadcasted over long distances. In and around urban areas are concentrations of powerful signal sources that produce a strong “baseline”, or ambient signal strength.

Analogue and digital signals

Analogue signals are on all the time. They convey information by modulating the amplitude or frequency, while digital signals conveys information via as a series of rapid pulse. On. Off. On. Off.
(FM stands for frequency modulation.)

Sniffer models

KITS/DIY SNIFFERS

1. Pinocio

(Photo: HC Gilje, Maxwell City, 2007)

Here’s Martin House and Erich Berger who put together the coil-based sniffer “Pinocio” (my name for it!) for close-up sniffing for the Maxwell City workshop I attended last year. It is also useful for sticking down holes! You need to plug the audio output via mini jack cable into the microphone input of a camera/other sound device to be able to hear the signal (it needs to be amplified). Listen via head phones from the headphone output of the camcorder.

We have one of these.

2. Little Sniff

(Photo: HC Gilje, Maxwell City, 2007)

Little Sniff can be heard without headphones. Its is an antenna-based EM sniffer that is built for this kit. It also derives from the Maxwell House workshop.

We have 2 of these.

CONSUMER SNIFFERS

3. Electrosmog “broadband” detector

Detects the pulsing emissions from wireless communications technologies (mobile phones, masts, DECT digital cordless phones, w/LAN’s, Wi-Fi, etc.)

• Frequency Range: 50 MHz to 3000 MHz
• Sensitivity: 0.01 volts per meter (V/m)
• Output: Audio Loudspeaker, Audio jack socket
• Controls: On/Off Switch, Volume

We have 1 of these

4. Zap checker enhanced

High sensitivity over a wide RF frequency range, with the ability to detect signals from wireless devices, cellular phones and covert “bugs” at more than 50+ feet, transmissions from “sealed” microwave ovens at 40+ feet, from walkie-talkies at 100+ feet, and from amateur radio transceivers at hundreds of feet.

• covers 1 MHz to 8 GHz.
• can be calibrated to detect different frequency ranges.
• needle display allows the user to view signal strength measurements
• audio output allows user to hear the difference in signal levels and distinguish between analog and digital signals.

(You will need to click the link above and read a description of how it works to find out which settings to use, and what you will hear/feel when you use them.)

We have one of these.

Sniffer set-up

This is the camcorder/electromagnetic detector (sniffer) set up we’ll be using at Sniffer Sounds.

1. Headphones plugged into headphones input on camcorder

2. Camcorder

3. Sniffer with audio signal output to camcorder via mini jack cable

4. Mini jack cable plugged in to microphone input on camcorder

(Don’t forget to press record to capture the sound of electromagnetic Lillehammer on the mini DV tape!)

The electromagnetic spectrum

The electromagnetic (EM) spectrum is the range of all possible electromagnetic radiation. The “electromagnetic spectrum” (usually just spectrum) of an object is the characteristic distribution of electromagnetic radiation from that object.

The electromagnetic spectrum extends from below the frequencies used for modern radio (at the long-wavelength end) through gamma radiation (at the short-wavelength end), covering wavelengths from thousands of kilometres down to a fraction the size of an atom.

[ Wikipedia. Read more here ]