Talk

TODAYS MEETING … Introduction to Radio Snooping

Speaker: Tim Peters (W3TLP)

Speaker Background

• 5th year, Extra Class amateur radio operator (highest license level)
• Primary board operator at Houghton Community Radio

Radio Snooping…

• Radio waves do not stop at borders or property lines
• In the United States, it is generally legal to listen to radio transmissions
  • Exception: cellular telephone communications

Radio Frequencies and Bands

• Radio frequencies are divided into bands within the electromagnetic spectrum
• Bands are typically defined by ITU, IEEE
• Commonly used bands:
  • LF, MF, HF, VHF, UHF, SHF

Scanner Radios

• A scanner radio is a receiver that rapidly scans through preprogrammed frequencies
• When activity is detected:
  • The scanner stops on that frequency
  • Remains there while the transmission is active
• Scanner radios are inexpensive and widely available

FCC and Spectrum Use

• The FCC (Federal Communications Commission) regulates radio spectrum use in the U.S.
• Specific frequency ranges are allocated to specific services

Common Radio Services

Amateur (Ham) Radio

• Used by licensed amateur operators worldwide
• Common bands range from 6m through 23cm
• Typically easy to monitor with analog receivers Modes
• AM (Amplitude Modulation)
• FM (Frequency Modulation)
• FM is the most common
• Digital modes also exist Typical traffic
• Casual conversation
• Emergency response
• Event coordination

VHF High Band

• Used by:
  • Fire departments
  • EMS
  • Business and dispatch radios
• Primarily FM, with some digital systems
• Includes paging for emergency and business users

VHF Low Band

• Largely obsolete
• Still used in some wildfire applications

Airband

• Used by aircraft and air traffic control
• Uses AM instead of FM
• Common traffic includes flight arrivals, departures, and coordination
• AM is used to reduce interference issues in aviation

Marine VHF

• Uses FM
• Focused on safety and navigation
• Includes bridge coordination and distress calls
• FM is more resistant to environmental interference

FRS / GMRS

• Consumer walkie-talkie services
• GMRS requires a license but uses the same frequencies as FRS
• Limited to 22 channels
• Easy to monitor with scanners Common traffic
• Recreational users
• Outdoor activities
• Retail and local communications

MURS

• Multi-Use Radio Service
• Low power (2 watts)
• Operates in VHF
• Used by some wildfire and utility services

UHF Business Bands

• Used primarily by commercial and business radios
• Generally unremarkable traffic

49 MHz Band

• Older cordless phones
• Baby monitors
• Legacy consumer devices
• Typically unencrypted and insecure

900 MHz ISM Band

• Industrial, Scientific, and Medical devices
• Shorter range
• Good building penetration

Radio Trunking Systems

• Conventional radio assigns a fixed frequency per user
• Large systems require many users to share limited spectrum

How Trunking Works

• Uses a control channel and multiple working channels
• When a user transmits:
  • A controller assigns an available working channel
• When transmission ends:
  • The radio returns to the control channel
• Allows many users to share the same infrastructure without interference

Michigan Public Safety Communications System (MPSCS)

• Statewide trunked radio system
• Used by most police and public safety agencies in Michigan
• Fully digital
• Cannot be monitored with analog scanners

Trunking Scanners

• Consumer-available scanners exist for trunked systems
• Significantly more expensive than basic scanners

Police Communications

• Most police radio traffic is encrypted (AES-256)
• Encrypted traffic cannot be monitored by non-authorized listeners
• Many other unencrypted services remain available to monitor

Notes

• Additional radio services exist beyond those listed

Post-meeting

FILL THIS FORM OUT FOR CYPHERCON!!! FORM