109 lines
4.7 KiB
Markdown
109 lines
4.7 KiB
Markdown
# SDR toolbox
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Nix flake providing programs for exploring an RTL-SDR stick.
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## Usage
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```sh
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cd ~/projects/sdr
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nix develop # drops you into a shell with all tools
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rtl_test # verify the stick is detected
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```
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Or install the whole set into your profile:
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```sh
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nix profile install .#sdr-tools
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```
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## One-time NixOS setup
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The kernel's DVB-T driver grabs the stick, and you need udev rules to use it
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without root. On NixOS add this to your `configuration.nix`:
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```nix
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hardware.rtl-sdr.enable = true; # udev rules + blacklists dvb_usb_rtl28xxu
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users.users.bender.extraGroups = [ "plugdev" ];
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```
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then rebuild and re-plug the stick.
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## What's included
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| Program | Try it for |
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| ------------- | ------------------------------------------------------------- |
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| `rtl_test` | Verify the dongle works |
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| `sdrpp` | Modern spectrum browser — tune around the FM band first |
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| `gqrx` | Classic waterfall receiver |
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| `rtl_433` | Neighborhood 433 MHz sensors: `rtl_433` |
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| `dump1090` | Aircraft tracking: `dump1090 --interactive` |
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| `multimon-ng` | Pagers etc.: `rtl_fm -f 466.230M -s 22050 \| multimon-ng -t raw -a POCSAG1200 -` |
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| `welle-io` | DAB+ digital radio |
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| `satdump` | Weather satellite images (NOAA APT, Meteor LRPT) |
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| `noaa-apt` | Simple NOAA APT decoding |
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| `wmbusmeters` | Decode wM-Bus / OMS smart meters (water, heat, gas, electric) |
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| `rtl_wmbus` | wM-Bus demodulator used under the hood by wmbusmeters |
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| `wmbus-listen`| Convenience wrapper: listen for OMS telegrams (see below) |
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## Listening to OMS / wM-Bus meters
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OMS smart meters transmit wireless M-Bus on 868.95 MHz (T1/C1 link modes).
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`wmbus-listen` drives the stick via `rtl_sdr | rtl_wmbus` and hands frames to
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`wmbusmeters`.
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```sh
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wmbus-listen # discovery: print the id/driver of every meter heard
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wmbus-listen Water multical21 12345678 00112233445566778899AABBCCDDEEFF
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# decode one meter (needs its id + AES key)
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```
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Discovery mode needs no keys — run it, note the ids and drivers that scroll by,
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then re-run with `NAME DRIVER ID KEY` to decode a meter you have the key for.
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Env overrides: `WMBUS_MODES` (default `c1,t1`), `WMBUS_FORMAT` (`json`/`fields`/`hr`).
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Both `wmbusmeters` and `rtl_wmbus` are built from source in the flake because
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they are no longer packaged in nixpkgs.
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## `oms-tui` — full-screen OMS monitor
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A Textual TUI that wraps `wmbusmeters`: a live list of detected meters on the
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left, a detail view / live telegram stream on the right.
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```sh
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oms-tui # live off the RTL-SDR (868.95 MHz, C1/T1)
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oms-tui --replay sample.msg # offline demo against the bundled capture
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oms-tui --import meters.csv # preload AES keys before listening
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```
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Keys:
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| Key | Action |
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| ------- | ---------------------------------------------------------------- |
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| `Enter` | select the highlighted device (show its details) |
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| `a` | deselect — show the live stream of *all* telegrams |
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| `k` | set/clear the AES key for the selected device (decrypts live) |
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| `e` | export the current device list to CSV (includes an `aes_key` col)|
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| `i` | import a CSV — loads keys and auto-decrypts those meters |
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| `q` | quit |
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Details include manufacturer, media/type, driver, version, RSSI, first/last
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seen, telegram count, the estimated **send interval** (median of the gaps
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between telegrams, so missed transmissions don't skew it — needs ≥2 telegrams),
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the encryption in use (OMS security mode 5 = AES-CBC,
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mode 7 = AES-CTR, or ELL AES-CTR), TPL/ELL layer info, and — once decoded — the
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latest measurement values with a timestamp. Unencrypted meters show as **open**
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(📖, readable without a key); encrypted ones are **locked** (🔒) until you add a
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key, then **decrypted** (🔓). The device list is in-memory and resets on each
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start; use `e`/`i` to persist.
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Both C1 and T1 link modes are listened to by default (`--listento=c1,t1`); add
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others (e.g. `--listento=c1,t1,s1`) if your meters use them.
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Workflow: run it, watch meters appear, select one and press `k` to paste its
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AES-128 key (32 hex chars) — it decrypts on the next telegram. Press `e` to save
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everything (keys included) to CSV, then `oms-tui --import that.csv` next time to
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come up already decrypting.
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> The CSV stores AES keys in plaintext — treat it like a password file.
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