The Airwaves

Flightradar24 says its main source is ADS-B, the position broadcast most aircraft send about once a second, picked up by more than 50,000 ground receivers, most of them user-built. For aircraft with only Mode S transponders it uses multilateration, and it adds satellite ADS-B over oceans and some radar data.

In the US, yes: 18 USC 2511 says it is not unlawful to intercept communications transmitted by any marine or aeronautical communications system. In the UK, a 2012 petition to Parliament stated that listening to services you are not authorized to receive is an offence, though that is a petitioner's statement, not an official ruling.

In the US, generally yes: the FCC says Section 705 of the Communications Act does not prohibit the mere interception of radio communications. Divulging or profiting from what you hear can violate it, scanners able to receive cellular frequencies are banned, and some states restrict scanners in vehicles.

The agency may have moved to digital P25, moved to P25 Phase 2, which many older scanners cannot decode, or encrypted its traffic. A newer scanner helps with the first two; encrypted traffic is not readily accessible to the public under the Wiretap Act.

Yes. Boston Police switched to a digital encrypted radio system on August 9, 2025. The department offers a free public feed at radio.rapidsos.com/boston, delayed about 5 minutes in most cases.

US law bars the FCC from authorizing scanners that can receive cellular frequencies, and such scanners could not be made or imported for US use after April 26, 1994. Intercepting phone calls can also bring severe criminal penalties under 18 U.S.C. 2510-2520.

Walls, floors and windows absorb or reflect radio waves, and the loss generally rises with frequency. Energy-saving low-E glass is especially hard on signals: one industry summary puts it at about 25-35 dB of loss at 3.5 GHz, against 5-8 dB for ordinary glass.

It means the device may operate without a license under the FCC's Part 15 rules. In exchange, it has no right to any frequency, must not cause harmful interference, and must accept interference from other users.

Under FCC Part 15 (47 CFR 15.5), unlicensed devices have no right to any frequency and must accept interference from licensed stations, other devices and ISM equipment. They must also not cause harmful interference, and must stop operating if the FCC says they are.

In the US, AM stations are assigned 540-1600 kHz in 10 kHz steps, and FM runs from 88 to 108 MHz with channels 200 kHz apart starting at 88.1 MHz. That spacing is why US FM frequencies end in an odd decimal.

Yes. The MBTA has had a distributed antenna system in its tunnels since a 2005 contract, built out line by line around 2010-2012, and American Tower later modernized it for 5G.

In the US, not necessarily. Unlicensed mics may operate in the TV bands at up to 50 mW EIRP under Part 15, must not cause harmful interference and must accept interference. Part 74 licenses, with more power, are open to broadcasters, film and TV producers, and large venues and sound companies using 50 or more devices.

In the US, the FCC limit is 1.6 W/kg averaged over any 1 gram of tissue. ICNIRP's 2020 guidelines set 2 W/kg over 10 grams for head and torso. The two use different averaging masses, so they are not directly comparable.

The WHO-commissioned review led by Ken Karipidis, published in Environment International in 2024, found moderate-certainty evidence that mobile phone use likely does not increase the risk of glioma, meningioma, acoustic neuroma and other head tumors. It screened over 5,000 studies and included 63, according to ARPANSA.

A microwave oven runs at about 1,000 W at 2.45 GHz, inside the same band as 2.4 GHz Wi-Fi, and some energy leaks around the door. A 2009 Design News test found an oven cut throughput by 21% on Wi-Fi channel 1 and 51% on channel 9. Using the 5 or 6 GHz band avoids the problem.

GPS.gov says GPS-enabled smartphones are typically accurate to within 4.9 m (16 ft) under open sky. Accuracy worsens near buildings, bridges and trees.

Tall buildings block satellites and reflect their signals (multipath), both listed by GPS.gov as causes of reduced accuracy. Fewer clear signals and bounced ones shift your computed position.

In the US, yes. The FCC says jammers have no lawful use in the United States and are per se illegal, citing federal law against willful interference and rules barring the sale or use of noncompliant devices.

WWVB is a NIST radio station near Fort Collins, Colorado that broadcasts a time code on 60 kHz. Radio-controlled ('atomic') clocks typically sync to it overnight.

Governments manage it rather than own it outright. In the US, the FCC administers spectrum for non-federal users and NTIA for federal government users, and many bands are shared between the two.

The FCC's C-band auction (Auction 107) closed its clock phase on 15 January 2021 at over $80.9 billion in gross bids, for 280 MHz at 3.7-3.98 GHz. The previous record was the 2015 AWS-3 auction at $44.9 billion.

WBZ is a Class A clear-channel AM station running 50,000 watts day and night from Hull. At night AM signals bounce off the upper atmosphere, and Fybush reported in 2005 that WBZ reached New York City strongly after dark.

Search the FCC's free Antenna Structure Registration database by coordinates and radius; it covers structures over 200 ft or near airports. Shorter antennas are better found through license records in the FCC's Universal Licensing System.

The Boston area NOAA Weather Radio signal is on 162.475 MHz from Blue Hill, Massachusetts. NOAA Weather Radio uses seven VHF channels between 162.400 and 162.550 MHz.

Channel 16, 156.800 MHz, is the international distress, safety and calling channel. The US Coast Guard announces safety broadcasts on 16 and then reads them on channel 22A.