The radio signals on a Miami street, band by band

Walk any street in Miami-Dade with a spectrum analyzer and the same families of signals appear again and again: broadcast stations, aircraft, boats, two-way radios, cell sites, smart meters and Wi-Fi. Almost everything that lights up has an everyday explanation. This guide tours the spectrum from the bottom to the top, describes what each signal looks like in a sweep and how it behaves from block to block, then covers what changes by time of day and weather, and how to plan a survey route that gives you results you can trust.

Before the tour: how to read what you see

A spectrum sweep is a graph of signal level against frequency. Each kind of transmitter has a recognisable shape: its width, how flat or peaked its top is, and whether it's there all the time or only in bursts. Learning those shapes is most of the skill. If the idea of a sweep is new, read what a spectrum analyzer is first.

Three things to keep in mind throughout:

• Levels are relative. Consentiva shows levels in dBFS, relative to the receiver's full scale, unless you've entered a calibration offset to show dBm. Compare one block with another and one day with another; don't treat a dBFS number as an absolute power. The units guide explains why.
• Average and peak-hold show different things. The average shows steady transmitters well. Peak-hold keeps the highest level seen at each frequency, which reveals brief bursts such as Wi-Fi, aircraft transponders and two-way radio.
• Your plan sets your window. The HackRF One covers 1 MHz–6 GHz. Consentiva's Free plan sweeps 30 MHz–2.7 GHz (with analysis locked), Standard sweeps up to 2.7 GHz and Full sweeps to 6 GHz. Signals above 2.7 GHz in this tour need Full.

Below 30 MHz: AM broadcast and CB

The US AM broadcast band runs from 530 to 1700 kHz. That's mostly below 1 MHz, which is where the HackRF's rated range and Consentiva's sweeps begin, so the lower part of the band isn't swept at all. The upper part (1–1.7 MHz) sits right at the edge of the HackRF's range, where its sensitivity is poorest, and the antennas people normally use with it are tiny compared with AM wavelengths of hundreds of metres. Don't expect AM stations to look like they do on a car radio, and don't read anything into their absence. AM is also unusual in that signals can travel much further at night, when they reflect off the upper atmosphere, so even a proper AM receiver hears a different band after dark.

Higher up, Citizens Band (CB) radio uses 40 channels between 26.965 and 27.405 MHz. You may catch a burst from a truck or a hobbyist on the Full plan, whose 1 MHz–6 GHz range reaches below 30 MHz; the Free and Standard ranges start at 30 MHz and won't show it.

FM broadcast: 88–108 MHz

FM stations are the first thing most people notice: a row of tall, steady bumps, each about 200 kHz wide, spaced across the band. Many US stations also transmit HD Radio, a digital signal carried as two flat shoulders on either side of the main FM peak, which makes those stations look wider and squarer.

FM transmitters are high-powered and usually mounted on tall towers, so their levels barely change from block to block. They do drop inside buildings, in underground garages and in the shadow of large structures. In a Consentiva report they're labelled FM broadcast and quickly become part of each block's normal. A sudden extra peak in the FM band that's only present on one block is more likely to be a low-power device, such as a car's FM transmitter for a phone, than a new station.

Aviation VHF: 108–137 MHz

This band belongs to aircraft and air traffic control. The lower part, 108–118 MHz, carries navigation beacons: VOR stations and the localiser part of instrument landing systems, which transmit continuously from fixed ground sites near airports and along air routes. The upper part, 118–137 MHz, carries voice between pilots and controllers, using AM.

Near Miami International Airport (MIA), or under approach paths, you'll see navigation beacons as steady narrow peaks and voice as short bursts that come and go. Aircraft transmissions are heard over long distances because the aircraft is high up, so you may catch them even well away from the airport. Further from airports, the band is usually quiet apart from these brief bursts.

Instrument landing systems also have a glide-slope signal around 329–335 MHz, which you may see from public roads near the ends of runways.

VHF high band: 138–174 MHz

This range is shared by many services. On a Miami street the most likely ones are business and government two-way radio, marine radio and weather radio.

Business and government two-way radio

Security teams, building maintenance, construction crews, utilities and some public agencies use VHF two-way radio between roughly 150 and 174 MHz. Each transmission is a narrow peak, a few kHz wide, lasting seconds. Some systems use repeaters on tall buildings, which re-transmit a handheld's signal at higher power, so you'll see a pair of frequencies light up together. This guide doesn't list any agency's frequencies; the FCC's licence records are the authoritative source for who's licensed where.

Marine VHF: 156–162.025 MHz

Near Biscayne Bay, the Miami River, marinas and the port, boats use marine VHF radio. Channel 16 (156.800 MHz) is the international calling and distress channel, which the Coast Guard monitors. Other channels carry ship-to-ship, harbour and marina traffic. Like other two-way radio, marine traffic appears as short narrow bursts.

The top of the marine band also carries AIS (Automatic Identification System) on 161.975 and 162.025 MHz. Ships and many boats transmit short digital bursts giving their identity and position every few seconds to minutes. Along the bayfront, peak-hold shows AIS as two narrow spikes that repeat.

NOAA Weather Radio: 162.400–162.550 MHz

NOAA Weather Radio broadcasts forecasts and warnings around the clock on seven channels between 162.400 and 162.550 MHz, 25 kHz apart. In most of Miami-Dade you should see at least one as a steady narrow peak that's there in every sweep. Its level changes gradually across a city. More on the service is at noaa.gov.

Broadcast TV: VHF and UHF

Digital TV in the US uses 6 MHz-wide channels. On a sweep each one looks like a flat-topped block 6 MHz wide, with a small pilot peak near its lower edge on ATSC 1.0 channels. Levels are steady, like FM.

• VHF high (174–216 MHz), channels 7–13, carries some stations.
• UHF (470–608 MHz), channels 14–36, carries most. After the FCC's spectrum auction and the repack that followed, TV no longer uses the frequencies above 608 MHz; the 600 MHz band above it was reassigned to mobile broadband.

Unused TV channels are sometimes used by wireless microphones at venues and productions, which appear as narrow peaks between the TV blocks for the duration of an event. Between 608 and 614 MHz is channel 37, which is kept free of TV for radio astronomy and some medical telemetry.

UHF two-way and personal radio: 450–470 MHz

The UHF business band is busy in cities because UHF signals get in and out of buildings well. Building security, hotel staff, retail, event crews and transit services use it. Inside this range sit FRS and GMRS channels around 462 and 467 MHz, used by the inexpensive walkie-talkies families and tour groups carry. A group walking past with their radios can make a block look unusual for the few seconds they talk.

Key fobs and gadgets: 315 and 433 MHz

Car key fobs and many tyre-pressure sensors in the US use 315 MHz. Wireless weather stations, doorbells and many small gadgets use 433 MHz. These devices send very short bursts only when used or every few seconds to minutes. Near parking lots and garages, peak-hold collects plenty of them. They're normal and rarely meaningful on their own.

Public safety and trunked radio: 700 and 800 MHz

Many US counties and cities run their public safety and government radio on trunked systems in the 700 and 800 MHz bands. In a trunked system a group of channels is shared by many users, and a computer assigns a channel for each call. Key ranges:

• 769–775 MHz and 799–805 MHz: 700 MHz public safety narrowband channels.
• 851–869 MHz: 800 MHz land mobile, where base stations and repeaters transmit; the matching mobile and handheld side is at 806–824 MHz.
• 758–768 MHz (downlink) and 788–798 MHz (uplink): band 14, FirstNet, the nationwide public safety broadband network.

The typical look of a trunked site is one or more control channels: narrow peaks that transmit continuously, so they appear in every sweep, with voice channels nearby popping up and down as calls happen. That means a block near a trunked site always has some steady peaks in this range. It's normal and isn't a sign of activity in that block.

Police cars, fire engines and other emergency vehicles carry radios in these bands and often a cellular data modem too. When one parks next to you, the uplink side of those bands can jump for as long as it's there.

Cellular: 600 MHz to 2.2 GHz

Cell sites produce the widest steady signals on the street: flat-topped blocks 5 to 20 MHz wide, sometimes several side by side. In Miami they come from towers, rooftop panels in Brickell and Downtown, and small cells on streetlights and poles. Downlink bands, where sites transmit, include:

• 600 MHz: 617–652 MHz
• 700 MHz: 729–746, 746–756 and 758–768 MHz (FirstNet)
• 850 MHz: 869–894 MHz
• PCS: 1930–1995 MHz
• AWS: 2110–2200 MHz

Cellular downlink levels vary a lot from block to block, much more than FM or TV, because sites are close, low and directional. That's exactly why Consentiva compares each block with its own normal rather than with a single city-wide figure. You'll also see the uplink bands (for example 824–849, 1710–1780 and 1850–1915 MHz) flicker with bursts from phones and data modems around you, including your own phone if it's close to the antenna. The cell towers guide explains how to trace a downlink signal back to its site.

Smart meters, sensors and LoRa: 902–928 MHz

The 902–928 MHz ISM band is one of the busiest unlicensed bands in a city. Many US electric utilities use smart meters that talk over mesh networks in this band, and FPL is the main electric utility across most of Miami-Dade, so homes and businesses there typically have a smart meter of some kind. Which radio a particular meter uses depends on the utility and the model, so don't assume. Other users include LoRa sensors and gateways, parking and water sensors, RFID readers at shops and warehouses, and some cordless devices.

In a sweep this band shows as many short, narrow bursts, often hopping between frequencies. Peak-hold fills the band with spikes; the average stays low. A block of apartments with a bank of meters on one wall may show more bursts than a block of offices, and that pattern is stable from day to day, which is what makes it part of the block's normal.

Aircraft transponders: 978, 1030 and 1090 MHz

Aircraft transponders reply on 1090 MHz when interrogated by ground radar or other aircraft, and many aircraft also broadcast ADS-B position reports on 1090 MHz without being asked. Interrogations from ground radars and aircraft collision-avoidance systems are on 1030 MHz. In the US, some smaller aircraft use a separate ADS-B system called UAT on 978 MHz.

All of these are very short pulses. On average they're invisible; on peak-hold 1090 MHz shows as a narrow spike whose height depends on how many aircraft are nearby and how close. Under the approach and departure paths around MIA, it can be one of the most consistently active spikes on the sweep. Near airports you may also see distance-measuring equipment pulses between about 960 and 1215 MHz.

GPS: 1575.42 MHz, and why you won't see it

GPS satellites transmit on the L1 frequency of 1575.42 MHz from about 20,000 km away. By the time the signal reaches the ground it's below the receiver's noise floor; GPS receivers recover it using signal processing, not because it's strong. So a normal sweep shows nothing at 1575 MHz. Your phone's GPS only receives, so it adds nothing to the sweep either. If you ever see a strong signal at that frequency, note it with a voice mark and walk the area again, because GPS itself shouldn't stand out.

Wi-Fi and Bluetooth: 2.4 GHz

The 2.4 GHz band (2400–2483.5 MHz) is shared by Wi-Fi, Bluetooth, many smart-home devices and microwave ovens. In Miami's apartment towers it's busy in every block.

• Wi-Fi appears as humps about 20 MHz wide. In the US most networks use channels 1, 6 and 11, centred on 2412, 2437 and 2462 MHz, so you'll often see three clusters.
• Bluetooth Classic hops quickly across 79 narrow channels, which on peak-hold looks like a grass of thin spikes across the whole band.
• Bluetooth Low Energy devices advertise on three channels at 2402, 2426 and 2480 MHz. Phones, earbuds, watches and trackers make these three spikes common wherever people are.
• Microwave ovens leak a broad, wobbly signal around 2.45 GHz while running. Near cafés and food trucks at lunchtime it's common.

Wi-Fi and Bluetooth are bursty, so peak-hold shows far more of them than the average. Walking past a café or an office lobby, the 2.4 GHz band may rise for a block and drop again. Crowds raise it too, because every phone in the crowd is advertising.

2.3–3.0 GHz: satellite radio, 2.5 GHz cellular and radar

Satellite radio uses 2320–2345 MHz, and in many US cities it has ground repeaters that transmit much more strongly than the satellites, so you may see a wide, steady block there in built-up areas. The 2.5 GHz band (2496–2690 MHz) is a major 5G band. It's TDD, meaning sites and phones take turns on the same frequencies, so the band shows a mixture of the site's steady signal and phones' bursts.

From 2.7 to 3.0 GHz you're in radar territory, which needs the Full plan. National Weather Service radars operate in this range and sweep the sky continuously; airport surveillance radars also use 2.7–2.9 GHz. Radar appears on peak-hold as pulses that come and go as the rotating beam passes, typically every few seconds. During storm season these are entirely normal. Marine radars on boats mostly use X-band around 9.4 GHz, well above the HackRF's range.

3.45–3.98 GHz: CBRS and 5G C-band

With the Full plan you'll see the newest mid-band 5G. 3.45–3.55 GHz and C-band at 3.7–3.98 GHz (n77) carry 5G from rooftop and tower sites, and CBRS at 3.55–3.7 GHz is shared spectrum used by carriers, private networks and some fixed wireless services. These are TDD bands and appear as very wide blocks, up to 100 MHz across for a single carrier. They fall off with distance and walls faster than the lower bands, so they vary a lot block by block. The 5G bands guide explains the layers in detail.

5 GHz and the edge of 6 GHz Wi-Fi

On the Full plan, 5 GHz Wi-Fi appears between roughly 5.15 and 5.85 GHz as humps 20, 40, 80 or 160 MHz wide. Near some large airports, Terminal Doppler Weather Radars operate around 5.6–5.65 GHz, and Wi-Fi routers are required to detect and avoid radars in parts of this band. Newer routers also use the 6 GHz band, which starts at 5925 MHz; the HackRF stops at 6 GHz, so you'll see only the very bottom of it.

The whole tour at a glance

Vehicles: the signals that move

A city street is full of moving transmitters, and many of the brief "unusual" moments in a survey turn out to be vehicles.

• Taxis, ride-share and delivery fleets often carry data modems for dispatch, tracking and payment. These are cellular uplink transmissions, short bursts that appear in uplink bands as the car passes or waits at a light.
• Buses commonly carry several radios: two-way voice, cellular data for tracking and fare systems, and sometimes on-board Wi-Fi. A bus stopped beside you can briefly raise several bands at once.
• Police and emergency vehicles carry radios in the public safety bands and usually a cellular modem. A patrol car parked on a corner can keep a block's readings high for as long as it stays.
• Private cars add key-fob and tyre-sensor bursts, phones, and in-car Wi-Fi hotspots and connected-car modems.
• Boats near the bay add marine VHF and AIS bursts.

The tell-tale sign of a vehicle is that the signal moves with something you can see, or vanishes when it leaves. If you catch one, a quick voice mark ("bus at the stop") saves you guessing later. With a paid plan you can also record a short video evidence clip, with time, GPS and the RF reading burned in, showing what was there. Keep the camera on the street, not pointed into homes or windows.

How levels change through the day

Consentiva learns a separate baseline for each block in four time windows: night, morning, afternoon and evening. That matters because many services follow daily rhythms.

This is why a comparison only makes sense within the same time window. A busy afternoon on a Brickell sidewalk will read higher in the cellular and Wi-Fi bands than the same sidewalk at night, and neither is unusual for its window.

Weather: humidity, rain and storms

Below 6 GHz, rain and humidity have little direct effect on signals over the distance of a few blocks; heavy rain attenuation matters mainly at much higher frequencies than the HackRF reaches. The effects you're more likely to notice are indirect:

• Wet trees and surfaces absorb and reflect more than dry ones, which can lower the higher bands slightly behind dense foliage.
• Behaviour changes: in rain, people move indoors and traffic changes, which shifts Wi-Fi, cellular uplink and vehicle signals.
• Tropospheric ducting: in warm, humid, stable conditions, VHF and UHF signals can sometimes travel much further than usual, so FM and TV stations from far away may briefly appear. It's a known natural effect, not a local transmitter.
• Storm season radar: weather radars are always on, but you may notice them more when you're looking at storm days.

If a survey day had unusual weather, note it with a voice mark at the start. When you compare it with the baseline later, you'll know why some bands moved.

Buildings, canyons and open water

Miami's mix of high-rise districts, low residential streets and open water creates very different radio environments within a short walk.

• Street canyons between tall buildings, as in Brickell and Downtown, channel signals along the street and reflect them off glass and concrete. Levels change quickly as you cross side streets, and a signal can arrive from the "wrong" direction.
• Coated glass on many modern towers blocks radio strongly, so levels can differ a lot between the sidewalk and the lobby.
• Open water along Biscayne Bay gives long, clear paths. Signals from across the bay, including from Miami Beach, can be stronger on a bayfront walkway than one block inland.
• Low residential streets are dominated by distant towers, a few small cells and the Wi-Fi of each house, with fewer reflections.
• Parking garages and underpasses block most signals, so a quiet reading there is expected.

What "normal per block" means

Consentiva divides your route into blocks of about 150 m and learns, from repeated walks, what's typical in each block for each of the four time windows. That learned normal is the baseline. Until it has enough walks, the app shows Learning.

After that, each new sweep is compared with the baseline for the same block and window. A signal much stronger than usual is flagged as unusual. Because the comparison is local, a block next to a rooftop site isn't flagged just for being strong; it's flagged only if it's stronger than it normally is. A quiet residential block, on the other hand, may be flagged for a signal that would be ordinary in Brickell.

Worked example: an unusual flag that explains itself

This is illustrative, not a measured case. You walk your usual evening route. One block turns amber in the report, with a peak in the UHF two-way range about 25 dB above that block's normal for the evening window. You check your voice marks: you'd said "event setting up in the park" on that block. The likely-service column suggests business two-way radio. The flag appears in only a few sweeps and is gone on the next evening's walk. That's a temporary crew with radios, and nothing more. If the same peak had appeared on several evenings with no visible cause, that would be worth another, more careful walk. Reading a Consentiva report explains each column, and the sample report shows the layout.

Signals labelled UNLISTED fall outside the common services Consentiva recognises. They're worth a second walk, but unlisted doesn't mean illegitimate: the US frequency allocation table is far longer than any short list.

Planning a survey route in Miami

A survey is only as good as its repeatability. The baseline learns from your walks, so the more alike they are, the more meaningful any difference becomes. The survey method guide covers the general approach; here's how to apply it on Miami streets.

1. Decide the question. "What's normal on my street?" needs repeated walks in each time window. "Did something change after the new small cell went up?" needs walks before and after on the same route.
2. Choose public sidewalks and paths. Plan the route on sidewalks, public parks and public waterfront walkways. Don't cross into private car parks, gated communities, building lobbies or marinas without permission.
3. Make it a loop of a sensible length. A loop of 1–3 km covers several blocks and takes 15–40 minutes at a steady pace, short enough to repeat in the same time window.
4. Walk both sides when it matters. In high-rise areas, the two sides of a wide street can read differently. If you care about one building, walk the side it's on, every time.
5. Keep a consistent pace. A steady walking pace gives each block a similar number of sweeps. Long stops add extra sweeps to one block; if you stop, say why in a voice mark.
6. Use the same time windows. Walk the same route at the same times of day on different days. Two or three walks per window is a good start for a baseline.
7. Hold the hardware the same way. Same antenna, same position relative to your body, personal phone in the same pocket away from the antenna. Changing the setup changes the readings.
8. Mark landmarks. Short audio notes at junctions ("Brickell and 8th") make the route map easy to read later.

Staying within the law and other people's privacy

• No trespass. Public sidewalks and paths only, unless you have the owner's permission.
• Don't record conversations. Florida law generally requires the consent of everyone in a private conversation before it's recorded. Use voice marks for your own short notes, and if a video clip would capture other people talking, don't record it.
• Point cameras at the street, not into homes. Evidence clips are for showing a location and a reading, not for filming through windows or into yards.
• Receive only. A spectrum survey listens; it doesn't transmit or interfere with anything. Its sweeps measure signal levels across frequencies rather than decoding anyone's communications.
• Be ready to explain. Someone may ask what you're doing. "I'm measuring radio signal levels along the street" is accurate and usually enough.

Heat, sun, storms and batteries

South Florida's climate shapes a survey as much as its radio environment does.

• Heat and phones: phones slow down, dim the screen or pause charging when they get hot, and a phone running the HackRF and GPS works hard. Keep it out of direct sun, use a light-coloured case or hold it in shade, and never leave it in a parked car.
• Battery: the HackRF draws its power from the phone over USB, so a survey drains the battery faster than normal use. Start fully charged, close other apps, and keep a power bank for recharging between loops.
• Time of day: early morning and evening walks are cooler for you and your phone. If you need afternoon data for the baseline, keep loops short.
• Afternoon storms: in the wet season, thunderstorms often build in the afternoon. Stop surveying when you hear thunder, and keep the hardware dry; neither the HackRF nor an exposed USB cable is waterproof.
• Hurricane season: the Atlantic season runs from June to November. After a storm, networks can look very different for a while, with sites off the air or temporary sites brought in, so treat post-storm walks as their own period rather than mixing them into the baseline.
• You: carry water, wear sun protection and plan routes with shade where you can.

Three scenario walk-throughs

These are illustrative descriptions of what you'd typically expect, not measurements from specific addresses.

A high-rise block in Brickell

FM and TV are present but lower than on open streets, shaded by the towers. Cellular downlink is strong and changeable: rooftop sites and small cells mean the mid bands rise and fall as you cross each side street. Wi-Fi and Bluetooth at 2.4 GHz are busy all day, peaking around lunchtime near cafés and in the evening near residential towers. UHF two-way bursts from building security and maintenance are common. Expect the baseline to have high levels in several bands; that's normal for the block. A survey here is most useful for spotting changes from that busy normal, so keeping the same time windows matters more than anywhere else.

A bayfront walkway

The open water gives long paths, so FM, TV and distant cell sites read more strongly than a block inland. Marine VHF bursts and the two AIS spikes near 162 MHz appear regularly, especially near marinas. NOAA Weather Radio is a steady peak. Wi-Fi is thinner away from buildings. Cellular uplink rises around benches and viewpoints where people gather. A block of walkway is a good place to see how much of a city's radio comes from far away.

A low residential street under a flight path

Here the steady signals are FM, TV, NOAA Weather Radio and one or two distant cell sites, with the low bands changing slowly along the street. Each house adds its own Wi-Fi and smart-home devices. The 902–928 MHz band shows a stable pattern of short bursts. As aircraft pass overhead, 1090 MHz peak-hold spikes rise and fall, and aviation voice bursts appear in 118–137 MHz. Because the baseline is quiet, a new small cell or a parked vehicle with radios stands out clearly, and the unusual flag is most informative on streets like this.

Troubleshooting

Common mistakes

• Treating dBFS as dBm. Without a calibration offset, levels are relative to the receiver, not absolute power.
• Reading "strong" as "unusual". A block near a rooftop site is strong every day. Unusual means stronger than that block's own normal.
• Mixing time windows. Comparing a busy afternoon with a quiet night always looks like a change.
• Ignoring vehicles. Many brief flags are a bus, a patrol car or a delivery van. Voice marks catch them.
• Changing the setup between walks. A different antenna or grip changes the readings and weakens the comparison.
• Surveying only once. One walk can't tell you what's normal.
• Assuming UNLISTED means suspicious. It means only that the signal isn't in Consentiva's list of common services.
• Treating a survey as an exposure measurement. Consentiva records signal levels; it doesn't measure RF exposure. For how official limits work, see RF exposure limits explained.

If a signal persists and you believe it's causing real interference, documenting radio interference for the FCC explains how to build a record, including Consentiva's tamper-evident evidence packages.

Glossary

• ADS-B: aircraft position broadcasts, mainly on 1090 MHz.
• AIS: the ship identification system on 161.975 and 162.025 MHz.
• Baseline: the learned normal level for a block and time window.
• Control channel: the continuously transmitting channel of a trunked radio site.
• dBFS: decibels relative to the receiver's full scale; an uncalibrated, relative level.
• Downlink / uplink: transmissions from a site to phones, and from phones to a site.
• ISM band: a band such as 902–928 MHz or 2.4 GHz that unlicensed devices share.
• Peak-hold: a display that keeps the highest level seen at each frequency, revealing short bursts.
• Repeater: a station that re-transmits two-way radio signals at higher power from a high location.
• Small cell: a low-power cell site on a pole or building that covers a few blocks.
• TDD: a band where sites and phones take turns on the same frequencies.
• Trunked system: a radio system that shares a pool of channels among many users.
• Tropospheric ducting: a weather effect that lets VHF and UHF signals travel unusually far.
• Unusual: Consentiva's flag for a signal stronger than that block's baseline for the time window.

Common questions

What radio signals are on a typical Miami street?

Expect FM and TV broadcast, NOAA Weather Radio, aviation and aircraft transponders, two-way and public safety radio, cellular bands, smart meters and sensors in 902-928 MHz, and Wi-Fi and Bluetooth. Near Biscayne Bay you'll also see marine VHF and AIS.

Can Consentiva show AM radio stations?

Not usefully. The AM band runs from 530 to 1700 kHz, mostly below the 1 MHz where the HackRF's range and Consentiva's sweeps begin, and the top of the band sits at the edge of the receiver's range.

Why does my block look unusual for only a moment?

Brief flags are often a vehicle with radios or data modems, a group using walkie-talkies, or a short two-way radio call. A voice mark at the time usually explains it.

Do rain and humidity change the readings?

Below 6 GHz, rain has little direct effect over a few blocks. You're more likely to see indirect changes from wet foliage, people moving indoors, or occasional long-distance VHF and UHF reception in warm, humid conditions.

Why can't I see GPS signals?

GPS satellites are about 20,000 km away and their signal arrives below the receiver's noise floor. GPS receivers recover it with signal processing, so a normal sweep shows nothing at 1575.42 MHz.

Which plan do I need to see 5G C-band and weather radar?

The Full plan, which sweeps to 6 GHz. Free and Standard sweep up to 2.7 GHz, which covers FM, TV, two-way radio, most cellular bands and 2.4 GHz Wi-Fi.

Is it legal to survey radio signals on a Miami sidewalk?

Receiving radio signal levels from a public sidewalk is a normal activity. Stay on public property, don't record other people's conversations, since Florida generally requires all-party consent, and don't aim cameras into homes.