[ { "see": "'VHF/UHF' printed on a TV antenna box or scanner", "is": "ITU band names: VHF is 30-300 MHz, UHF is 300-3,000 MHz", "section": "basics", "anchor": "What do VHF and UHF stand for?", "tags": [ "vhf", "uhf", "antenna", "bands", "scanner" ], "c": "wht", "sid": "what-do-vhf-and-uhf-stand-for" }, { "see": "'2.4 GHz' or '6 GHz' on a Wi-Fi router box", "is": "The radio frequency the router transmits on, counted in hertz", "section": "basics", "anchor": "What is a radio frequency, and what does \"hertz\" mean?", "tags": [ "hertz", "ghz", "frequency", "router", "wifi" ], "c": "wht", "sid": "what-is-a-radio-frequency-and-what-does-hertz-mean" }, { "see": "Full bars outside, one bar or none inside a building", "is": "Walls and especially energy-saving glass absorb or reflect signals, more so at higher frequencies", "section": "basics", "anchor": "Why does my phone lose signal inside buildings?", "tags": [ "indoor", "signal", "glass", "buildings", "bars" ], "c": "wht", "sid": "why-does-my-phone-lose-signal-inside-buildings" }, { "see": "A '5G UW' or '5G+' icon that vanishes when I walk indoors", "is": "Higher-frequency 5G carries more data but gets through walls poorly", "section": "basics", "anchor": "Why do high frequencies carry more data?", "tags": [ "5g", "mmwave", "speed", "indoor", "cband" ], "c": "wht", "sid": "why-do-high-frequencies-carry-more-data" }, { "see": "Coverage map says good service but my phone struggles indoors", "is": "Outdoor maps do not capture building entry loss, which varies with construction", "section": "basics", "anchor": "What is \"building entry loss,\" and how do engineers model it?", "tags": [ "coverage", "map", "building", "loss" ], "c": "wht", "sid": "what-is-building-entry-loss-and-how-do-engineers-model-it" }, { "see": "A museum caption saying the Titanic created radio laws", "is": "The Radio Act of 1912 followed the Titanic and required radio licenses", "section": "basics", "anchor": "Did the Titanic lead to radio laws?", "tags": [ "titanic", "1912", "history", "license" ], "c": "wht", "sid": "did-the-titanic-lead-to-radio-laws" }, { "see": "A colorful US frequency allocation chart poster", "is": "NTIA's wall chart of the US Table of Frequency Allocations", "section": "rules", "anchor": "What is the US frequency allocation chart?", "tags": [ "chart", "poster", "allocation", "ntia" ], "c": "pnk", "sid": "what-is-the-us-frequency-allocation-chart" }, { "see": "'This device complies with Part 15 of the FCC Rules' label", "is": "The device runs without a license, on condition it causes no harmful interference and accepts interference", "section": "rules", "anchor": "What does \"FCC Part 15\" on my device mean?", "tags": [ "fcc", "part15", "label", "unlicensed", "fccid" ], "c": "pnk", "sid": "what-does-fcc-part-15-on-my-device-mean" }, { "see": "Wi-Fi slows down when the microwave oven runs", "is": "Wi-Fi shares ISM bands, and Part 15 devices must accept interference from ISM equipment", "section": "rules", "anchor": "What are ISM bands, and why do so many gadgets share them?", "tags": [ "microwave", "wifi", "interference", "ism", "2.4ghz" ], "c": "pnk", "sid": "what-are-ism-bands-and-why-do-so-many-gadgets-share-them" }, { "see": "A router advertising Wi-Fi 6E or Wi-Fi 7", "is": "Uses the 6 GHz band the FCC opened for unlicensed use in April 2020", "section": "rules", "anchor": "What is 6 GHz Wi-Fi, and is it legal?", "tags": [ "6ghz", "wifi6e", "wifi7", "router", "afc" ], "c": "pnk", "sid": "what-is-6-ghz-wi-fi-and-is-it-legal" }, { "see": "A news story about a carrier buying spectrum for billions", "is": "An FCC spectrum auction; licenses, not ownership, are sold", "section": "rules", "anchor": "Why does the government auction airwaves?", "tags": [ "auction", "spectrum", "carrier", "fcc", "cband" ], "c": "pnk", "sid": "why-does-the-government-auction-airwaves" }, { "see": "Headlines about WRC-27", "is": "The 2027 ITU World Radiocommunication Conference in Shanghai, which revises the global radio treaty", "section": "rules", "anchor": "When is the next World Radiocommunication Conference?", "tags": [ "itu", "wrc", "treaty", "shanghai" ], "c": "pnk", "sid": "when-is-the-next-world-radiocommunication-conference" }, { "see": "A car radio with AM and FM bands", "is": "Two broadcast bands: AM varies signal strength, FM varies frequency", "section": "broadcast", "anchor": "What is the difference between AM and FM?", "tags": [ "am", "fm", "radio", "car radio", "frequency" ], "c": "org", "sid": "what-is-the-difference-between-am-and-fm" }, { "see": "Far-away AM stations showing up at night", "is": "AM medium-wave signals can travel much farther after dark", "section": "broadcast", "anchor": "What is the difference between AM and FM?", "tags": [ "am", "night", "distant", "skywave" ], "c": "org", "sid": "what-is-the-difference-between-am-and-fm" }, { "see": "The stereo light flickering off on an FM station", "is": "A weak signal makes the radio drop the 38 kHz stereo subcarrier and go mono", "section": "broadcast", "anchor": "How does FM carry stereo on one station?", "tags": [ "fm", "stereo", "mono", "static" ], "c": "org", "sid": "how-does-fm-carry-stereo-on-one-station" }, { "see": "An HD logo or HD2 channel on my car stereo", "is": "HD Radio, the US digital system riding alongside AM and FM stations", "section": "broadcast", "anchor": "What is HD Radio, and what is DAB?", "tags": [ "hd radio", "digital radio", "hd2", "iboc" ], "c": "org", "sid": "what-is-hd-radio-and-what-is-dab" }, { "see": "A DAB radio in the UK", "is": "Digital radio where many stations share one multiplex", "section": "broadcast", "anchor": "What is HD Radio, and what is DAB?", "tags": [ "dab", "uk", "digital radio", "multiplex" ], "c": "org", "sid": "what-is-hd-radio-and-what-is-dab" }, { "see": "My TV lost channels until I rescanned it", "is": "The 2017-2020 TV repack moved stations to new frequencies", "section": "broadcast", "anchor": "Why did TV go digital, and why did I have to rescan my TV?", "tags": [ "rescan", "antenna tv", "repack", "channels" ], "c": "org", "sid": "why-did-tv-go-digital-and-why-did-i-have-to-rescan-my-tv" }, { "see": "A NextGen TV logo on a new television", "is": "ATSC 3.0, the optional newer US broadcast TV standard", "section": "broadcast", "anchor": "What is NextGen TV (ATSC 3.0), and is regular TV being shut off?", "tags": [ "nextgen tv", "atsc 3.0", "tv", "antenna" ], "c": "org", "sid": "what-is-nextgen-tv-atsc-3-0-and-is-regular-tv-being-shut-off" }, { "see": "Tall lit towers along Route 128 in Needham", "is": "Boston's main TV transmitter sites, Cedar Street and Cabot Street", "section": "broadcast", "anchor": "In Boston: what are the towers in Needham?", "tags": [ "needham", "tv tower", "boston", "candelabra" ], "c": "org", "sid": "in-boston-what-are-the-towers-in-needham" }, { "see": "A tower with a wide triangular top holding several antennas", "is": "A candelabra tower carrying several TV stations at once", "section": "broadcast", "anchor": "In Boston: what are the towers in Needham?", "tags": [ "candelabra", "tower", "tv", "antennas" ], "c": "org", "sid": "in-boston-what-are-the-towers-in-needham" }, { "see": "Bars on my phone changing as I walk", "is": "Your phone being served by, and handed off between, cell sites", "section": "cellular", "anchor": "How does a cell network work?", "tags": [ "signal bars", "handoff", "cell tower", "phone" ], "c": "blu", "sid": "how-does-a-cell-network-work" }, { "see": "A 5G or LTE icon next to my signal bars", "is": "Which cellular generation your phone is using right now", "section": "cellular", "anchor": "What do 1G, 2G, 3G, 4G and 5G mean?", "tags": [ "5g", "lte", "4g", "icon" ], "c": "blu", "sid": "what-do-1g-2g-3g-4g-and-5g-mean" }, { "see": "A canister or box on top of a light pole", "is": "Probably a small cell adding cellular capacity to a busy block", "section": "cellular", "anchor": "Is that a cell tower or a small cell?", "tags": [ "small cell", "pole", "5g", "antenna" ], "c": "blu", "sid": "is-that-a-cell-tower-or-a-small-cell" }, { "see": "Rows of rectangular panels at the top of a tall tower", "is": "A macro cell site covering a wide area", "section": "cellular", "anchor": "Is that a cell tower or a small cell?", "tags": [ "cell tower", "macro", "panels", "antenna" ], "c": "blu", "sid": "is-that-a-cell-tower-or-a-small-cell" }, { "see": "My phone is much faster on some corners than others", "is": "Different 5G tiers: low band, mid band and short-range mmWave", "section": "cellular", "anchor": "What do low-band, mid-band and mmWave 5G mean?", "tags": [ "5g", "mmwave", "c-band", "speed" ], "c": "blu", "sid": "what-do-low-band-mid-band-and-mmwave-5g-mean" }, { "see": "News about 5G and airplane altimeters", "is": "The 2021-2022 FAA dispute over C-band 5G near airports", "section": "cellular", "anchor": "Why did 5G cause problems for airplanes?", "tags": [ "5g", "airplanes", "altimeter", "faa", "c-band" ], "c": "blu", "sid": "why-did-5g-cause-problems-for-airplanes" }, { "see": "Small antennas on subway tunnel walls", "is": "A distributed antenna system carrying cell signal underground", "section": "cellular", "anchor": "What is a DAS, and why is there signal in some tunnels?", "tags": [ "das", "subway", "tunnel", "antenna" ], "c": "blu", "sid": "what-is-a-das-and-why-is-there-signal-in-some-tunnels" }, { "see": "Cell service on the T underground", "is": "The MBTA's tunnel DAS, in place since 2005 and upgraded for 5G", "section": "cellular", "anchor": "In Boston", "tags": [ "mbta", "subway", "boston", "das", "cell service" ], "c": "blu", "sid": "in-boston" }, { "see": "My old phone or alarm panel stopped working in 2022", "is": "US carriers shut down their 3G networks in 2022 and January 2023", "section": "cellular", "anchor": "Why did my old phone stop working?", "tags": [ "3g", "shutdown", "old phone", "alarm" ], "c": "blu", "sid": "why-did-my-old-phone-stop-working" }, { "see": "UK phone lost 3G", "is": "UK operators switched off 3G between 2023 and 2025", "section": "cellular", "anchor": "Elsewhere in the world", "tags": [ "uk", "3g", "switch-off", "2g" ], "c": "blu", "sid": "elsewhere-in-the-world" }, { "see": "A radio clipped to a police officer's vest with a microphone on the shoulder", "is": "Land mobile radio, push-to-talk radio that works through repeaters", "section": "public-safety", "anchor": "What is the radio on an officer's shoulder?", "tags": [ "police", "radio", "lmr", "walkie-talkie", "repeater" ], "c": "red", "sid": "what-is-the-radio-on-an-officer-s-shoulder" }, { "see": "A scanner listing that says P25 Phase 1 or Phase 2", "is": "The digital public safety radio standard and its two versions", "section": "public-safety", "anchor": "What is P25, and what does \"Phase 2\" mean?", "tags": [ "p25", "digital", "phase 2", "scanner", "tdma" ], "c": "red", "sid": "what-is-p25-and-what-does-phase-2-mean" }, { "see": "Scanner audio that sounds digital and hops between frequencies", "is": "A trunked system, where a control channel assigns each conversation a free frequency", "section": "public-safety", "anchor": "What is the radio on an officer's shoulder?", "tags": [ "trunked", "talkgroup", "control channel", "scanner" ], "c": "red", "sid": "what-is-the-radio-on-an-officer-s-shoulder" }, { "see": "A rugged tablet or modem in an ambulance or police cruiser", "is": "Possibly FirstNet, the US first-responder broadband network on Band 14", "section": "public-safety", "anchor": "What is FirstNet?", "tags": [ "firstnet", "band 14", "att", "broadband", "700 mhz" ], "c": "red", "sid": "what-is-firstnet" }, { "see": "Scanner channels named BAPERN or MetroFire around Boston", "is": "Greater Boston's regional police and fire mutual aid radio on the T-Band", "section": "public-safety", "anchor": "In Boston: what are BAPERN and the T-Band?", "tags": [ "bapern", "boston", "t-band", "metrofire", "mutual aid" ], "c": "red", "sid": "in-boston-what-are-bapern-and-the-t-band" }, { "see": "Radio chatter on 160-161 MHz near a rail line", "is": "Railroad VHF radio between crews and dispatchers", "section": "public-safety", "anchor": "What is that chatter near the train tracks?", "tags": [ "railroad", "train", "vhf", "160 mhz", "nxdn" ], "c": "red", "sid": "what-is-that-chatter-near-the-train-tracks" }, { "see": "A harsh two-tone alarm interrupting TV or radio", "is": "The Emergency Alert System", "section": "public-safety", "anchor": "What is the loud tone before an emergency message on TV or radio?", "tags": [ "eas", "alert", "tone", "tv", "radio" ], "c": "red", "sid": "what-is-the-loud-tone-before-an-emergency-message-on-tv-or-radio" }, { "see": "Every phone in a room blaring an alert at the same time", "is": "A Wireless Emergency Alert sent by cell broadcast", "section": "public-safety", "anchor": "Why did every phone in the room go off at once?", "tags": [ "wea", "phone alert", "amber alert", "cell broadcast" ], "c": "red", "sid": "why-did-every-phone-in-the-room-go-off-at-once" }, { "see": "A weather radio that sits silent then sounds an alarm", "is": "NOAA Weather Radio activated by SAME codes for your county", "section": "public-safety", "anchor": "What is on 162.475 MHz?", "tags": [ "weather radio", "noaa", "same", "162 mhz" ], "c": "red", "sid": "what-is-on-162-475-mhz" }, { "see": "A UK phone alert test on a Sunday afternoon", "is": "The UK Emergency Alerts system, first tested nationally April 23, 2023", "section": "public-safety", "anchor": "Elsewhere in the world", "tags": [ "uk", "emergency alert", "test", "cell broadcast" ], "c": "red", "sid": "elsewhere-in-the-world" }, { "see": "A scanner for sale at an electronics store", "is": "Legal to own and use for unencrypted public radio in the US, with limits on sharing", "section": "scanners", "anchor": "Is it legal to own a police scanner in the US?", "tags": [ "scanner", "legal", "section 705", "police" ], "c": "red", "sid": "is-it-legal-to-own-a-police-scanner-in-the-us" }, { "see": "A Facebook group posting what's on the police scanner", "is": "Divulging scanner traffic, restricted by Section 705 but questioned after Bartnicki v. Vopper", "section": "scanners", "anchor": "Can I post or use what I hear on a scanner?", "tags": [ "divulge", "social media", "section 705", "bartnicki" ], "c": "red", "sid": "can-i-post-or-use-what-i-hear-on-a-scanner" }, { "see": "A gap in a scanner's frequency coverage labeled cellular", "is": "Federally required blocking of cellular frequencies", "section": "scanners", "anchor": "Why can't a scanner pick up cell phone calls?", "tags": [ "cellular", "blocked", "scanner", "fcc" ], "c": "red", "sid": "why-can-t-a-scanner-pick-up-cell-phone-calls" }, { "see": "A scanner mounted on a car dashboard", "is": "Restricted in some states, such as Florida and New York", "section": "scanners", "anchor": "Can I have a scanner in my car?", "tags": [ "car", "vehicle", "state law", "scanner" ], "c": "red", "sid": "can-i-have-a-scanner-in-my-car" }, { "see": "My scanner used to get local police and now it is silent", "is": "The agency went digital, moved to P25 Phase 2, or encrypted", "section": "scanners", "anchor": "Why did my scanner go quiet, and do I need a digital one?", "tags": [ "silent", "encrypted", "digital", "phase 2" ], "c": "red", "sid": "why-did-my-scanner-go-quiet-and-do-i-need-a-digital-one" }, { "see": "Boston police missing from my scanner app", "is": "BPD encrypted on August 9, 2025, and offers a 5-minute delayed feed", "section": "scanners", "anchor": "In Boston: why can't I hear the police on my scanner?", "tags": [ "boston", "bpd", "encrypted", "rapidsos", "delay" ], "c": "red", "sid": "in-boston-why-can-t-i-hear-the-police-on-my-scanner" }, { "see": "A news story about police radio going dark", "is": "Police encryption, and the debate between officer safety and public access", "section": "scanners", "anchor": "Why are police departments encrypting their radios?", "tags": [ "encryption", "police", "journalists", "transparency" ], "c": "red", "sid": "why-are-police-departments-encrypting-their-radios" }, { "see": "A UK scanner leaflet warning what you may listen to", "is": "Section 48 of the Wireless Telegraphy Act 2006", "section": "scanners", "anchor": "Elsewhere in the world", "tags": [ "uk", "wireless telegraphy act", "scanner", "law" ], "c": "red", "sid": "elsewhere-in-the-world" }, { "see": "A flight tracker app showing a plane over my house", "is": "The plane's own ADS-B broadcast, picked up by volunteer ground receivers", "section": "aviation", "anchor": "What is ADS-B, and why can anyone receive it?", "tags": [ "adsb", "flightradar24", "plane", "tracker", "app" ], "c": "yel", "sid": "what-is-ads-b-and-why-can-anyone-receive-it" }, { "see": "A plane labeled UAT or 978 on a tracking site", "is": "A US-only ADS-B link used mainly by small aircraft below 18,000 ft", "section": "aviation", "anchor": "What is the difference between 1090 and 978 ADS-B?", "tags": [ "uat", "978", "1090", "adsb" ], "c": "yel", "sid": "what-is-the-difference-between-1090-and-978-ads-b" }, { "see": "A plane on a tracker marked MLAT or with an estimated position", "is": "An aircraft with only a Mode S transponder, located by timing its replies at four or more receivers", "section": "aviation", "anchor": "What is MLAT, and why can't I see a plane on Flightradar24?", "tags": [ "mlat", "mode s", "multilateration", "transponder" ], "c": "yel", "sid": "what-is-mlat-and-why-can-t-i-see-a-plane-on-flightradar24" }, { "see": "A plane I can hear but cannot find on Flightradar24", "is": "Too low for MLAT, outside receiver coverage, on 978 MHz, or blocked by its owner", "section": "aviation", "anchor": "What is MLAT, and why can't I see a plane on Flightradar24?", "tags": [ "missing", "flightradar24", "coverage", "blocked" ], "c": "yel", "sid": "what-is-mlat-and-why-can-t-i-see-a-plane-on-flightradar24" }, { "see": "A private jet that shows up blank or not at all on a tracker", "is": "The owner has used the FAA's LADD blocking or a Privacy ICAO Address", "section": "aviation", "anchor": "Can owners hide a plane from flight trackers?", "tags": [ "ladd", "pia", "private jet", "privacy", "blocked" ], "c": "yel", "sid": "can-owners-hide-a-plane-from-flight-trackers" }, { "see": "Military jets showing on one tracking site but not another", "is": "ADS-B Exchange describes itself as unfiltered, including military traffic", "section": "aviation", "anchor": "What is ADS-B Exchange?", "tags": [ "adsb exchange", "military", "unfiltered", "tracker" ], "c": "yel", "sid": "what-is-ads-b-exchange" }, { "see": "Short digital bursts on a scanner around 129-131 MHz", "is": "ACARS, text messaging between aircraft and their airlines", "section": "aviation", "anchor": "What is ACARS?", "tags": [ "acars", "datalink", "scanner", "vdl" ], "c": "yel", "sid": "what-is-acars" }, { "see": "Clipped voices on a scanner between 118 and 137 MHz", "is": "Air traffic control and pilots on the VHF airband", "section": "aviation", "anchor": "What frequency is air traffic control?", "tags": [ "airband", "atc", "scanner", "121.5" ], "c": "yel", "sid": "what-frequency-is-air-traffic-control" }, { "see": "A website streaming live tower audio", "is": "Listening to aeronautical radio is permitted under US federal law; the UK is described as stricter", "section": "aviation", "anchor": "Is it legal to listen to air traffic control?", "tags": [ "liveatc", "legal", "scanner", "uk", "atc" ], "c": "yel", "sid": "is-it-legal-to-listen-to-air-traffic-control" }, { "see": "A transponder or squawk code mentioned in a flight tracker", "is": "The radar-reply box on the aircraft and the four-digit code ATC assigns", "section": "aviation", "anchor": "What does a transponder do?", "tags": [ "transponder", "squawk", "mode s", "radar" ], "c": "yel", "sid": "what-does-a-transponder-do" }, { "see": "Jets climbing in a steady line over Cambridge or Somerville", "is": "Runway 33L RNAV departures from Logan, concentrated on a narrow track since 2013-2014", "section": "aviation", "anchor": "In Boston: why do planes fly low over certain neighborhoods?", "tags": [ "logan", "noise", "rnav", "somerville", "cambridge" ], "c": "yel", "sid": "in-boston-why-do-planes-fly-low-over-certain-neighborhoods" }, { "see": "A ship app showing a ferry or tanker in the harbor", "is": "The vessel's AIS broadcast on 161.975/162.025 MHz, collected by shore receivers", "section": "ships", "anchor": "What is AIS?", "tags": [ "ais", "marinetraffic", "ship", "tracker" ], "c": "blu", "sid": "what-is-ais" }, { "see": "Big ships on a tracker but not small sailboats", "is": "SOLAS and US rules require AIS on larger and commercial vessels, not most recreational boats", "section": "ships", "anchor": "Which ships have to carry AIS?", "tags": [ "ais", "solas", "boats", "carriage" ], "c": "blu", "sid": "which-ships-have-to-carry-ais" }, { "see": "A tug or ferry showing on a ship tracker", "is": "US rules require Class A AIS on commercial vessels of 65 ft or more, larger towing vessels and big passenger vessels", "section": "ships", "anchor": "What are the US rules for AIS?", "tags": [ "ais", "tug", "ferry", "class a" ], "c": "blu", "sid": "what-are-the-us-rules-for-ais" }, { "see": "A world map of ship icons that thins out at sea", "is": "MarineTraffic's network of coastal AIS receivers, mostly run by contributors", "section": "ships", "anchor": "How does MarineTraffic track ships?", "tags": [ "marinetraffic", "ais", "receiver", "coverage" ], "c": "blu", "sid": "how-does-marinetraffic-track-ships" }, { "see": "A marine radio or scanner tuned to channel 16", "is": "The international distress, safety and calling channel, 156.800 MHz", "section": "ships", "anchor": "What is marine VHF channel 16?", "tags": [ "channel 16", "marine vhf", "distress", "156.8" ], "c": "blu", "sid": "what-is-marine-vhf-channel-16" }, { "see": "A short data burst on marine channel 70", "is": "Digital Selective Calling, with no voice", "section": "ships", "anchor": "What is marine VHF channel 16?", "tags": [ "dsc", "channel 70", "marine", "digital" ], "c": "blu", "sid": "what-is-marine-vhf-channel-16" }, { "see": "A handheld scanner at the waterfront picking up boats", "is": "Receiving marine radio is permitted under US federal law", "section": "ships", "anchor": "Can I listen to marine radio?", "tags": [ "marine radio", "legal", "scanner", "listen" ], "c": "blu", "sid": "can-i-listen-to-marine-radio" }, { "see": "A line of buoys in the water around Logan Airport", "is": "A 250-ft security zone marked by 29 buoys, set up in 2002", "section": "ships", "anchor": "In Boston", "tags": [ "logan", "buoys", "security zone", "harbor" ], "c": "blu", "sid": "in-boston" }, { "see": "A blue dot that drifts across the street downtown", "is": "GPS multipath and blocked satellites in an urban canyon", "section": "gps", "anchor": "Why is my GPS wrong downtown?", "tags": [ "gps", "multipath", "urban canyon", "phone", "accuracy" ], "c": "grn", "sid": "why-is-my-gps-wrong-downtown" }, { "see": "A pale circle around my location dot", "is": "The phone's own estimate of its position error", "section": "gps", "anchor": "How accurate is GPS on my phone?", "tags": [ "gps", "accuracy", "map", "phone" ], "c": "grn", "sid": "how-accurate-is-gps-on-my-phone" }, { "see": "A GPS test app showing satellites with different country flags", "is": "Your phone using GPS, GLONASS, Galileo and BeiDou together", "section": "gps", "anchor": "Is my phone using GPS, or something else?", "tags": [ "gnss", "galileo", "glonass", "beidou", "satellites" ], "c": "grn", "sid": "is-my-phone-using-gps-or-something-else" }, { "see": "Dual-frequency GPS (L1 + L5) on a phone spec sheet", "is": "A receiver using two GPS carriers to correct atmospheric delay", "section": "gps", "anchor": "What frequencies does GPS use?", "tags": [ "l5", "l1", "gps", "frequency", "dual-frequency" ], "c": "grn", "sid": "what-frequencies-does-gps-use" }, { "see": "A small dome or puck antenna on a cell site", "is": "Possibly a GPS antenna; cell networks rely on GPS for precise timing", "section": "gps", "anchor": "Why do cell towers and power grids need GPS?", "tags": [ "timing", "cell tower", "gps antenna", "grid" ], "c": "grn", "sid": "why-do-cell-towers-and-power-grids-need-gps" }, { "see": "A 'GPS privacy' plug-in device for sale online", "is": "A GPS jammer, which the FCC says has no lawful use in the US", "section": "gps", "anchor": "Are GPS jammers illegal?", "tags": [ "jammer", "illegal", "fcc", "gps" ], "c": "grn", "sid": "are-gps-jammers-illegal" }, { "see": "A plane on a flight tracker flying a strange zigzag near a border", "is": "Possible GNSS jamming or spoofing affecting its reported position", "section": "gps", "anchor": "Why are planes losing GPS over the Baltic?", "tags": [ "spoofing", "jamming", "aviation", "ads-b", "flight tracker" ], "c": "grn", "sid": "why-are-planes-losing-gps-over-the-baltic" }, { "see": "An 'atomic' clock with a tower icon that syncs overnight", "is": "A radio-controlled clock receiving NIST's WWVB on 60 kHz", "section": "gps", "anchor": "How does an \"atomic\" clock set itself?", "tags": [ "wwvb", "atomic clock", "60 khz", "radio-controlled" ], "c": "grn", "sid": "how-does-an-atomic-clock-set-itself" }, { "see": "A ticking voice announcing Coordinated Universal Time on shortwave", "is": "NIST's WWV or WWVH time station", "section": "gps", "anchor": "What is that ticking voice on shortwave?", "tags": [ "wwv", "wwvh", "shortwave", "time signal" ], "c": "grn", "sid": "what-is-that-ticking-voice-on-shortwave" }, { "see": "Old tutorials for receiving NOAA weather images on 137 MHz", "is": "NOAA APT, shut down in 2025", "section": "satellites", "anchor": "Can I still pick up NOAA weather satellite pictures?", "tags": [ "noaa", "apt", "137 mhz", "weather satellite" ], "c": "pur", "sid": "can-i-still-pick-up-noaa-weather-satellite-pictures" }, { "see": "A cloud loop of all North America on the TV forecast", "is": "Imagery from NOAA's geostationary GOES satellites", "section": "satellites", "anchor": "What is GOES, and why does it never move?", "tags": [ "goes", "weather", "satellite", "noaa" ], "c": "pur", "sid": "what-is-goes-and-why-does-it-never-move" }, { "see": "A bright steady light crossing the sky in a few minutes", "is": "Often the International Space Station", "section": "satellites", "anchor": "Can I hear the International Space Station?", "tags": [ "iss", "ariss", "ham radio", "space station" ], "c": "pur", "sid": "can-i-hear-the-international-space-station" }, { "see": "Smeared pictures with 'ARISS' in the corner posted online", "is": "SSTV images received from the ISS on 145.800 MHz", "section": "satellites", "anchor": "What is SSTV from the ISS, and how do people receive it?", "tags": [ "sstv", "iss", "145.800", "ariss" ], "c": "pur", "sid": "what-is-sstv-from-the-iss-and-how-do-people-receive-it" }, { "see": "A line of satellites moving together after sunset", "is": "Starlink satellites", "section": "satellites", "anchor": "How many Starlink satellites are there?", "tags": [ "starlink", "satellite train", "spacex" ], "c": "pur", "sid": "how-many-starlink-satellites-are-there" }, { "see": "A flat white Starlink dish on a roof or RV", "is": "A Starlink user terminal using Ku/Ka-band links", "section": "satellites", "anchor": "What frequencies does Starlink use?", "tags": [ "starlink", "dish", "ku band", "ka band" ], "c": "pur", "sid": "what-frequencies-does-starlink-use" }, { "see": "My phone shows 'SAT' with no bars", "is": "Direct-to-cell satellite texting, such as T-Mobile T-Satellite", "section": "satellites", "anchor": "How can my phone text from space?", "tags": [ "direct-to-cell", "t-satellite", "starlink", "texting" ], "c": "pur", "sid": "how-can-my-phone-text-from-space" }, { "see": "\"This device must accept any interference received\" in a gadget manual", "is": "The FCC Part 15 condition for unlicensed radios: no protected frequency, no harmful interference allowed.", "section": "unlicensed", "anchor": "What does \"must accept any interference received\" mean?", "tags": [ "fcc", "part 15", "label", "unlicensed" ], "c": "grn", "sid": "what-does-must-accept-any-interference-received-mean" }, { "see": "Wi-Fi cuts out when the microwave is running", "is": "The oven leaks 2.45 GHz energy into 2.4 GHz Wi-Fi channels 7-11.", "section": "unlicensed", "anchor": "Why does my Wi-Fi drop when the microwave is on?", "tags": [ "wifi", "microwave", "interference", "2.4 ghz" ], "c": "grn", "sid": "why-does-my-wi-fi-drop-when-the-microwave-is-on" }, { "see": "A router box labeled Wi-Fi 6, 6E or 7", "is": "Wi-Fi Alliance generation names for IEEE 802.11ax and 802.11be.", "section": "unlicensed", "anchor": "What do Wi-Fi 4, 5, 6 and 7 mean?", "tags": [ "wifi 7", "wifi 6", "router", "802.11" ], "c": "grn", "sid": "what-do-wi-fi-4-5-6-and-7-mean" }, { "see": "My router shows separate 2.4 GHz, 5 GHz and 6 GHz networks", "is": "Three unlicensed bands with different range and capacity trade-offs.", "section": "unlicensed", "anchor": "Why does my router have 2.4, 5 and 6 GHz bands?", "tags": [ "wifi", "bands", "6 ghz", "router" ], "c": "grn", "sid": "why-does-my-router-have-2-4-5-and-6-ghz-bands" }, { "see": "My phone shows no 6 GHz Wi-Fi while traveling in Europe", "is": "The EU opened only the lower part of the 6 GHz band.", "section": "unlicensed", "anchor": "Can I use 6 GHz Wi-Fi outside the US?", "tags": [ "6 ghz", "europe", "uk", "travel" ], "c": "grn", "sid": "can-i-use-6-ghz-wi-fi-outside-the-us" }, { "see": "The blue angular Bluetooth \"B\" logo", "is": "Runic-style branding for a 2.4 GHz short-range radio named after a Danish king.", "section": "unlicensed", "anchor": "Why is Bluetooth called Bluetooth?", "tags": [ "bluetooth", "logo", "name", "ble" ], "c": "grn", "sid": "why-is-bluetooth-called-bluetooth" }, { "see": "A store app that knows which aisle I am in", "is": "A BLE beacon broadcasting an ID that the app recognizes.", "section": "unlicensed", "anchor": "What is a Bluetooth beacon?", "tags": [ "beacon", "ibeacon", "ble", "store" ], "c": "grn", "sid": "what-is-a-bluetooth-beacon" }, { "see": "A Matter, Thread, Zigbee or Z-Wave logo on a smart bulb or lock box", "is": "Low-power smart-home mesh radios and the Matter standard that runs over them.", "section": "unlicensed", "anchor": "What are Zigbee, Z-Wave, Thread and Matter?", "tags": [ "smart home", "matter", "thread", "zigbee", "z-wave" ], "c": "grn", "sid": "what-are-zigbee-z-wave-thread-and-matter" }, { "see": "A small box with a stubby antenna on a meter, fence or bin labeled LoRaWAN", "is": "A long-range, low-data-rate IoT sensor, at 915 MHz in the US.", "section": "unlicensed", "anchor": "What is LoRa, and how far does it reach?", "tags": [ "lora", "lorawan", "iot", "sensor" ], "c": "grn", "sid": "what-is-lora-and-how-far-does-it-reach" }, { "see": "A Helium crypto hotspot in a window", "is": "A crowd-built LoRaWAN gateway that earns tokens.", "section": "unlicensed", "anchor": "What is the Helium network, and is it legit?", "tags": [ "helium", "crypto", "hotspot", "lorawan" ], "c": "grn", "sid": "what-is-the-helium-network-and-is-it-legit" }, { "see": "A new digital electric meter with no spinning dial", "is": "An AMI smart meter that reports readings by radio, often a 902-928 MHz mesh.", "section": "everyday", "anchor": "What is that new electric meter, and does it transmit?", "tags": [ "smart meter", "ami", "eversource", "national grid" ], "c": "yel", "sid": "what-is-that-new-electric-meter-and-does-it-transmit" }, { "see": "A letter from Eversource scheduling a meter swap", "is": "Eversource's Massachusetts smart meter rollout, due to finish by late 2027.", "section": "everyday", "anchor": "When is Eversource installing smart meters in Massachusetts?", "tags": [ "eversource", "smart meter", "massachusetts", "rollout" ], "c": "yel", "sid": "when-is-eversource-installing-smart-meters-in-massachusetts" }, { "see": "A National Grid notice about a new meter", "is": "National Grid's Massachusetts smart meter rollout, with a fee-based opt-out.", "section": "everyday", "anchor": "Can I opt out of a National Grid smart meter in Massachusetts?", "tags": [ "national grid", "opt out", "smart meter", "massachusetts" ], "c": "yel", "sid": "can-i-opt-out-of-a-national-grid-smart-meter-in-massachusetts" }, { "see": "The amber horseshoe-shaped tire warning light on my dashboard", "is": "The TPMS warning, fed by 315 or 434 MHz sensors in each wheel.", "section": "everyday", "anchor": "What frequency do tire pressure sensors use?", "tags": [ "tpms", "tire", "dashboard", "315 mhz" ], "c": "yel", "sid": "what-frequency-do-tire-pressure-sensors-use" }, { "see": "The four curved lines of the contactless symbol", "is": "A 13.56 MHz tap-range link powered by the reader.", "section": "everyday", "anchor": "How does tap-to-pay work, and how close do I need to be?", "tags": [ "nfc", "contactless", "tap to pay", "13.56 mhz" ], "c": "yel", "sid": "how-does-tap-to-pay-work-and-how-close-do-i-need-to-be" }, { "see": "A green CharlieCard or an MBTA gate that takes my phone", "is": "MBTA fare media: MIFARE Classic CharlieCard since 2006, contactless bank cards since August 2024.", "section": "everyday", "anchor": "Is the CharlieCard being replaced?", "tags": [ "charliecard", "mbta", "tap to ride", "fare" ], "c": "yel", "sid": "is-the-charliecard-being-replaced" }, { "see": "A gray toll tag behind the rearview mirror", "is": "An E-ZPass active RFID transponder at 915 MHz.", "section": "everyday", "anchor": "How does E-ZPass work?", "tags": [ "e-zpass", "toll", "rfid", "915 mhz" ], "c": "yel", "sid": "how-does-e-zpass-work" }, { "see": "A highway sign showing minutes to the next town", "is": "Travel times computed by matching Bluetooth MAC addresses at roadside readers.", "section": "everyday", "anchor": "How do highway signs know the travel time?", "tags": [ "travel time", "bluetooth", "massdot", "highway sign" ], "c": "yel", "sid": "how-do-highway-signs-know-the-travel-time" }, { "see": "A presenter with a belt-pack transmitter and no mic cable", "is": "A wireless mic, a low-power transmitter sharing leftover TV spectrum", "section": "show-wireless", "anchor": "Who is allowed to put a microphone on the air?", "tags": [ "wireless mic", "lavalier", "belt pack", "part 74" ], "c": "pnk", "sid": "who-is-allowed-to-put-a-microphone-on-the-air" }, { "see": "A singer wearing a molded earpiece on stage", "is": "An in-ear monitor, a wireless transmitter sending the performer their mix", "section": "show-wireless", "anchor": "Who is allowed to put a microphone on the air?", "tags": [ "iem", "in-ear monitor", "earpiece", "concert" ], "c": "pnk", "sid": "who-is-allowed-to-put-a-microphone-on-the-air" }, { "see": "A \"50 mW\" notice in a wireless mic manual", "is": "The US power cap for unlicensed mics in the TV bands", "section": "show-wireless", "anchor": "What is the 50 mW rule?", "tags": [ "50 mw", "unlicensed", "part 15", "eirp" ], "c": "pnk", "sid": "what-is-the-50-mw-rule" }, { "see": "A cheap secondhand mic system labeled 700-something MHz", "is": "A 700 MHz mic, banned in the US since 2010", "section": "show-wireless", "anchor": "What happened to 700 MHz wireless microphones?", "tags": [ "700 mhz", "illegal mic", "used gear" ], "c": "pnk", "sid": "what-happened-to-700-mhz-wireless-microphones" }, { "see": "A wireless mic receiver tuned between 617 and 698 MHz", "is": "A 600 MHz mic that had to stop operating in the US by July 13, 2020", "section": "show-wireless", "anchor": "Is my 600 MHz wireless mic illegal?", "tags": [ "600 mhz", "illegal mic", "incentive auction" ], "c": "pnk", "sid": "is-my-600-mhz-wireless-mic-illegal" }, { "see": "Referees and coaches all on wireless at an NFL game", "is": "Hundreds of coordinated frequencies managed by SBE/NFL volunteers", "section": "show-wireless", "anchor": "Who coordinates frequencies at the Super Bowl?", "tags": [ "super bowl", "nfl", "frequency coordination", "sbe" ], "c": "pnk", "sid": "who-coordinates-frequencies-at-the-super-bowl" }, { "see": "A small antenna box on a lighting truss", "is": "Probably wireless DMX lighting control on 2.4 GHz", "section": "show-wireless", "anchor": "What about wireless lighting control?", "tags": [ "dmx", "lighting", "2.4 ghz", "truss" ], "c": "pnk", "sid": "what-about-wireless-lighting-control" }, { "see": "A license plate like W1ABC on a car with a tall antenna", "is": "Likely a ham radio operator's call sign", "section": "hobby", "anchor": "What is a ham, and how do you become one in the US?", "tags": [ "ham", "call sign", "license plate", "amateur radio" ], "c": "org", "sid": "what-is-a-ham-and-how-do-you-become-one-in-the-us" }, { "see": "A UK call sign starting M7, M8, M9 or M0", "is": "A UK amateur licence; the prefix shows the licence level", "section": "hobby", "anchor": "What are the UK amateur radio licence levels?", "tags": [ "uk", "ofcom", "call sign", "licence" ], "c": "org", "sid": "what-are-the-uk-amateur-radio-licence-levels" }, { "see": "A flyer for a radio \"swapfest\" in Cambridge", "is": "The MIT Swapfest, run by the MIT Radio Society W1MX", "section": "hobby", "anchor": "Are there ham radio clubs in Boston?", "tags": [ "swapfest", "mit", "boston", "club" ], "c": "org", "sid": "are-there-ham-radio-clubs-in-boston" }, { "see": "A USB stick with an antenna showing a rainbow waterfall on a laptop", "is": "An RTL-SDR, a cheap receive-only software-defined radio", "section": "hobby", "anchor": "What is a software-defined radio, and what is an RTL-SDR?", "tags": [ "sdr", "rtl-sdr", "dongle", "waterfall" ], "c": "org", "sid": "what-is-a-software-defined-radio-and-what-is-an-rtl-sdr" }, { "see": "A flight tracker map with planes over my house", "is": "Aircraft ADS-B position broadcasts, receivable with an SDR", "section": "hobby", "anchor": "What can I listen to with an RTL-SDR?", "tags": [ "ads-b", "flight tracker", "planes", "logan" ], "c": "org", "sid": "what-can-i-listen-to-with-an-rtl-sdr" }, { "see": "A creepy buzzing shortwave station on YouTube", "is": "UVB-76 \"The Buzzer\" on 4625 kHz", "section": "hobby", "anchor": "What is UVB-76, \"The Buzzer\"?", "tags": [ "uvb-76", "buzzer", "number station", "shortwave" ], "c": "org", "sid": "what-is-uvb-76-the-buzzer" }, { "see": "A SAR number in my phone's legal settings", "is": "How much RF energy the phone deposits in tissue, tested against FCC or ICNIRP limits", "section": "health", "anchor": "What is the SAR limit for cell phones in the US?", "tags": [ "sar", "phone", "radiation", "fcc" ], "c": "wht", "sid": "what-is-the-sar-limit-for-cell-phones-in-the-us" }, { "see": "Different SAR limits for the same phone in the US and Europe", "is": "Different averaging masses: 1.6 W/kg over 1 g (FCC) vs 2 W/kg over 10 g (ICNIRP)", "section": "health", "anchor": "Why is the US limit 1.6 and Europe's 2.0?", "tags": [ "sar", "icnirp", "europe", "1.6" ], "c": "wht", "sid": "why-is-the-us-limit-1-6-and-europe-s-2-0" }, { "see": "A headline saying WHO says phones may cause cancer", "is": "IARC's 2011 Group 2B classification, based on limited evidence", "section": "health", "anchor": "What does \"possibly carcinogenic\" (Group 2B) mean?", "tags": [ "iarc", "cancer", "2b", "who" ], "c": "wht", "sid": "what-does-possibly-carcinogenic-group-2b-mean" }, { "see": "A post claiming 5G masts make people sick", "is": "WHO says no adverse health effect has been causally linked to wireless technologies", "section": "health", "anchor": "Is 5G dangerous to health?", "tags": [ "5g", "health", "mast", "who" ], "c": "wht", "sid": "is-5g-dangerous-to-health" }, { "see": "Tall towers near Route 128 in Needham", "is": "Boston's TV antenna farm: WBZ-TV's Cedar Street tower and the Cabot Street candelabra.", "section": "boston", "anchor": "Where do Boston TV stations broadcast from?", "tags": [ "needham", "tv", "towers", "route 128", "antenna" ], "c": "blu", "sid": "where-do-boston-tv-stations-broadcast-from" }, { "see": "A tower whose top splits into several arms", "is": "A candelabra tower, holding a separate antenna for each TV station.", "section": "boston", "anchor": "What is the stainless-steel tower with arms in Needham?", "tags": [ "candelabra", "tower", "needham", "tv" ], "c": "blu", "sid": "what-is-the-stainless-steel-tower-with-arms-in-needham" }, { "see": "A mast on top of the Prudential", "is": "An FM broadcast mast with a shared master antenna (as of 2004).", "section": "boston", "anchor": "What antennas are on top of the Prudential?", "tags": [ "prudential", "fm", "mast", "downtown" ], "c": "blu", "sid": "what-antennas-are-on-top-of-the-prudential" }, { "see": "WBZ 1030 coming in from hundreds of miles away at night", "is": "A 50 kW clear-channel AM station whose night skywave travels far.", "section": "boston", "anchor": "Why can I hear WBZ 1030 at night in other states?", "tags": [ "wbz", "am", "skywave", "night", "clear channel" ], "c": "blu", "sid": "why-can-i-hear-wbz-1030-at-night-in-other-states" }, { "see": "Two bare towers by the water in Hull", "is": "WBZ's directional AM array, aimed at Boston and away from the Atlantic.", "section": "boston", "anchor": "Where is WBZ's transmitter?", "tags": [ "wbz", "hull", "am", "towers" ], "c": "blu", "sid": "where-is-wbz-s-transmitter" }, { "see": "My phone works in the subway tunnel", "is": "A distributed antenna system carries carrier signals over fiber and leaky cable.", "section": "boston", "anchor": "How does cell service reach the T tunnels?", "tags": [ "mbta", "subway", "cell", "das", "tunnel" ], "c": "blu", "sid": "how-does-cell-service-reach-the-t-tunnels" }, { "see": "Radios on MBTA staff and Transit Police", "is": "The MBTA is replacing EDACS with an L3Harris P25 system.", "section": "boston", "anchor": "What radio do MBTA crews and Transit Police use?", "tags": [ "mbta", "p25", "l3harris", "radio" ], "c": "blu", "sid": "what-radio-do-mbta-crews-and-transit-police-use" }, { "see": "Boston police and fire radio on a scanner app", "is": "A UHF P25 system being upgraded across ten city radio sites.", "section": "boston", "anchor": "What radio system do Boston police and firefighters use?", "tags": [ "boston police", "fire", "p25", "uhf", "scanner" ], "c": "blu", "sid": "what-radio-system-do-boston-police-and-firefighters-use" }, { "see": "Planes flying low over my house in Somerville or Milton", "is": "Logan runway use and satellite-guided RNAV paths concentrate tracks.", "section": "boston", "anchor": "Why are planes flying over my house in Somerville, Cambridge or Milton?", "tags": [ "logan", "planes", "noise", "rnav", "massport" ], "c": "blu", "sid": "why-are-planes-flying-over-my-house-in-somerville-cambridge-or-milton" }, { "see": "A flight tracker showing a plane over Boston", "is": "Massport runs a near-live public Flight Monitor for Logan traffic.", "section": "boston", "anchor": "How can I tell which plane just flew over Boston?", "tags": [ "flight tracker", "logan", "massport", "planes" ], "c": "blu", "sid": "how-can-i-tell-which-plane-just-flew-over-boston" }, { "see": "A ship-tracking website showing a tanker in the harbor", "is": "Ships broadcast position and identity on AIS, on dedicated marine VHF channels.", "section": "boston", "anchor": "How do I track ships in Boston Harbor?", "tags": [ "ais", "ships", "harbor", "vhf", "marine" ], "c": "blu", "sid": "how-do-i-track-ships-in-boston-harbor" }, { "see": "A new Eversource meter on my house", "is": "An Itron smart meter that reports usage daily by radio.", "section": "boston", "anchor": "What is the new meter on my house, and can I opt out?", "tags": [ "smart meter", "eversource", "itron", "opt out" ], "c": "blu", "sid": "what-is-the-new-meter-on-my-house-and-can-i-opt-out" }, { "see": "A Christmas Eve transmission on 486 kHz", "is": "WA1ZMS's experimental-license commemoration of Fessenden's claimed 1906 broadcast.", "section": "boston", "anchor": "Was the first radio broadcast really from Brant Rock in 1906?", "tags": [ "fessenden", "brant rock", "1906", "history" ], "c": "blu", "sid": "was-the-first-radio-broadcast-really-from-brant-rock-in-1906" }, { "see": "A Marconi marker on a Cape Cod bluff", "is": "The site of Marconi's 1903 Wellfleet transatlantic station.", "section": "boston", "anchor": "Where was Marconi's station on Cape Cod?", "tags": [ "marconi", "wellfleet", "cape cod", "history" ], "c": "blu", "sid": "where-was-marconi-s-station-on-cape-cod" }, { "see": "A cluster of towers on a hill", "is": "An antenna farm, where stations share height, land and backup.", "section": "towers", "anchor": "What is an antenna farm?", "tags": [ "antenna farm", "towers", "hill" ], "c": "org", "sid": "what-is-an-antenna-farm" }, { "see": "A very tall tower held up by cables", "is": "A guyed tower.", "section": "towers", "anchor": "How do I tell a guyed tower from a candelabra?", "tags": [ "guyed", "tower", "cables" ], "c": "org", "sid": "how-do-i-tell-a-guyed-tower-from-a-candelabra" }, { "see": "Several identical bare towers in a row", "is": "An AM directional array; the towers themselves are the antenna.", "section": "towers", "anchor": "Why do AM stations use several tall towers?", "tags": [ "am", "array", "towers", "directional" ], "c": "org", "sid": "why-do-am-stations-use-several-tall-towers" }, { "see": "Stacked rectangular panels on a rooftop mast", "is": "Often FM broadcast panel antennas, though cell panels look similar.", "section": "towers", "anchor": "What are the flat panels on a rooftop mast?", "tags": [ "panel", "rooftop", "fm", "bay" ], "c": "org", "sid": "what-are-the-flat-panels-on-a-rooftop-mast" }, { "see": "A thick cable along a subway tunnel wall", "is": "Radiating (leaky feeder) cable from a distributed antenna system.", "section": "towers", "anchor": "What carries cell signals into a tunnel?", "tags": [ "leaky feeder", "tunnel", "das", "cable" ], "c": "org", "sid": "what-carries-cell-signals-into-a-tunnel" }, { "see": "Who owns that tower?", "is": "Look it up free in the FCC's ASR database by coordinates and radius.", "section": "towers", "anchor": "How do I look up a tower near me?", "tags": [ "asr", "fcc", "tower", "owner", "lookup" ], "c": "org", "sid": "how-do-i-look-up-a-tower-near-me" }, { "see": "Who is licensed to transmit from that antenna?", "is": "Search the FCC's Universal Licensing System.", "section": "towers", "anchor": "How do I find out who holds a radio license?", "tags": [ "uls", "fcc", "license", "lookup" ], "c": "org", "sid": "how-do-i-find-out-who-holds-a-radio-license" } ]