WavelensWavelens blog: detection guides and companion how-tos
Read the guides, or skip them
Everything on this blog is built into the companions we sell: Spotter $64 and Full Spectrum $499, programmed and tested. The Android app is a free beta now. Everyone who joins the Android beta before the Play Store launch gets the Play version free with a promo code.
Shop Join the free Android beta
Every command here is copied from a Pi we run · open firmware and bridge on GitHub · receive only
How to check your car for a hidden tracker: what a phone scan finds, and what only your hands will
Trackers on cars come in three kinds, and only one of them can be found with a radio scan alone. Here is what each kind is, how to sweep the car with an Android phone, the places a hidden unit actually ends up, and what to do if you find one, including when not to pull it off straight away. Read →
What your phone can detect, what an ESP32 adds, and what only an SDR will hear
A phone hears Bluetooth and Wi-Fi, and nothing else. An ESP32 hears the same bands, but more of them and further out. A software-defined radio hears the rest of the spectrum below 1.7 GHz: tyre sensors, key fobs, public-safety radio, aircraft. Here is what each one detects, in one table, so you buy only what you need. Read →
Free updates for life: how a Spotter and a Scanner stay current without a computer
Every companion we sell, and every one you build from the guide, updates itself from the same place: the public repo. The Spotter takes new firmware from the phone over Bluetooth; the Scanner pulls its own over Wi-Fi, checks itself, and rolls back if the new version won't start. Here is how each path works, what it can't break, and what to do if a radio is too old to know about any of this. Read →
wavelens.local:8080 — the Scanner's admin page, for Wi-Fi, logs, settings and updates from your phone
The Raspberry Pi companion now has a small web page of its own. Open it from any phone or laptop on the same Wi-Fi and you can join a network, read the bridge's log, change the radio's name and flags, install or roll back an update, flash a Spotter plugged into the Pi, or reboot — with a password, on your LAN only, no cloud anywhere. Read →
Build log, 3 November: updates for life, an admin page, corrections that teach the app, and P25 for very little money
A long day. The companions got a real update system, the Pi got a web page, the app learned to take corrections (that was an ambulance, not a body cam) and to stay quiet when you tell it to, the detection sheet got colour, and the site says out loud that a $60 build does what a $600 digital scanner does. Everything, in the order it landed. Read →
Spotter: what the $64 ESP32 companion hears, and why it hears more than your phone
Spotter is the starting tier: a pre-programmed dual-band ESP32-C5 in a black enclosure with a stealth antenna, $64 shipped free in the US. It works on its own: no Raspberry Pi or computer, just USB power and your phone. It listens to every Wi-Fi beacon and Bluetooth advert on the channel it parks on, from much further out than a phone, and hands each hit to Wavelens over Bluetooth. Here's what's in the box, how the antenna mod works, what it finds, and how to put it in a car. Read →
The Raspberry Pi companion: decodes sensors, follows trunked radio and names who's transmitting
The Raspberry Pi companion is the heart of Full Spectrum: a Raspberry Pi 4 (4 GB) with the Wavelens bridge installed, starting on its own. With its two pre-configured RTL-SDRs it decodes tyre sensors and remotes by name, sweeps the public-safety bands, follows P25 and Motorola trunked systems, and tells you whose licence a carrier belongs to. Here's what the bridge does, what each dongle is for, and what the Pi arrives with. Build it from the free guide, or get it set up and tested in the $499 Full Spectrum kit. Read →
Full Spectrum: the $499 kit that covers a car from 300 MHz to 5 GHz
Full Spectrum is the one we recommend: a pre-programmed Raspberry Pi 4 (4 GB), two pre-configured RTL-SDRs with their antennas, and a Spotter ESP32, set up together and tested as one rig before they ship. Pair the Pi as the main companion and the ESP32 as the second, and the phone, the Pi and the ESP32 all listen at once. Here's exactly what's in the box, how the jobs are divided, and how it goes into a car. Read →
The pre-configured RTL-SDR: what a $40 dongle with the right antenna actually does
Every RTL-SDR we sell is $40, comes with the antenna for its job, and is set up and tested with the Wavelens bridge. This post is about the dongle itself: what it receives, why a TCXO matters, why the antenna decides more than the dongle, and which job to give it on a Pi you already have. Read →
Ready-made companion radios: Spotter and Full Spectrum
You can now buy a Wavelens companion that is already programmed, set up for where you'll use it and tested before it ships. Two tiers, the $64 Spotter and the $499 Full Spectrum kit, plus add-ons: protective cases and USB cables. Read →
How to make, share and import custom signature packs
Wavelens ships with US settings built in. A pack is one small JSON file that sets it up for where you drive: km/h or mph, local device rules, rules switched off where they don't apply, and the band names a companion radio uses. Here's how to import one, how to make your own, and how to share it. Read →
How to program an ESP32 for Wavelens
A $10 ESP32 board becomes a Wi-Fi and Bluetooth sniffer that hears every beacon on a channel and hands the hits to Wavelens over Bluetooth. Programming it takes one tool and one command. Here's the whole process on Windows, Mac and Linux, plus updating it later and what to do when the upload won't start. Read →
Turn a $30 RTL-SDR and a Raspberry Pi into a digital public-safety scanner
A trunked P25 scanner used to mean a $500 Uniden. The same thing — control channel, talkgroups, named agencies — runs on a Pi 4, one RTL-SDR and free software, with the audio arriving on your phone over Bluetooth. Here's the whole build, and why each piece is there. Read →
Which RTL-SDR dongle? What we learned at 800 MHz
The RTL-SDR Blog V4 is the better radio on paper. On our Pi it produced nothing, then fell off the bus, while two no-name R820T sticks heard every control channel in the county. What actually matters when you pick a dongle for a car scanner. Read →
Two dongles, two jobs: a scanner that also decodes TPMS, sensors and aircraft
One RTL-SDR can only do one thing at a time. The scanner needs it continuously, so the moment you want tyre sensors, weather stations and planes overhead as well, you need a second stick — and a plan for who gets which. Read →
Find any trunked system's control channel with rtl_power — no database needed
RadioReference tells you where the control channels are — if you have a subscription and the list is current. The signal itself tells you too: a control channel is the one carrier that never, ever stops. Here is how the bridge finds it from a plain power sweep. Read →
Why your P25 audio sounds chopped into syllables (and the one-flag fix)
The system locks instantly, talkgroups are named, and every call sounds like a robot with hiccups. It's not your antenna. Countywide systems transmit from several towers at once, and the resulting signal needs a different demodulator. Read →
A clean car install: power, antennas, and where the Pi lives
The software is the easy part. A Pi that reboots at every traffic light, a dongle that cooks on the dash and an antenna inside a metal box are what actually stop a car scanner working. The parts and placement that have held up. Read →
Put agency names on every talkgroup with a RadioReference export
Out of the box the scanner says 'TG 532'. With one CSV it says 'FD 1K (Fire-Tac)', picks the right decoder per system, and knows which sites are near you. How to export, where to put it, and the Public safety / Fire / EMS filter it unlocks. Read →
Streaming scanner audio over Bluetooth LE without it falling apart
BLE wasn't built for audio. It gives you ~20 kB/s on a good day, in 240-byte notifications, with jitter. Here's the codec, framing and buffering that turned 'one word at a time' into continuous dispatch audio, and the four mistakes along the way. Read →
Build a $25 analog scanner from an ESP32 and an SA818 module
No Pi, no SDR: a $5 ESP32 and a $12 SA818 FM module give you a Bluetooth scanner for VHF or UHF analog — marine, air band (AM aside), ham repeaters, business, fire-ground — with a scan list from the phone and audio over the same BLE link the Pi uses. Read →
What the journal is telling you: a field guide to the bridge's log
The Alerts tab shows the companion's last 100 log lines, live. Most of what scrolls past is normal. Here is what each line means, which ones are a problem, and what to do about them — collected from a month of logs. Read →
That's every guide so far
New ones land as the hardware does. Until then: the Android beta is free, and the radios it works with are in the shop.