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BeaconLine Advertisement in JSON Format

Alternative representation to BEACON-LINE Advertisement in CSV Format: BLE advertisements observed by the Bline anchor are output as one JSON object per reception — NDJSON / JSON Lines (one complete JSON object per line, separated by \n), not as one large JSON array. Same fields as in the CSV format, but with native JSON types instead of a flat comma list. One of the fields still contains the complete raw BLE data as a hex string, decoded according to BLE/taskit BLE Manufacturer Advertisement.

1. Object Structure

{"ts_ms": <uint64>, "anchor": "<string>", "mac": "<string>", "rssi": <int8>, "connectable": <bool>, "adv_hex": "<hex-string>", "node_name": "<string|null>"}
Field Type Unit / Values Description Corresponds to CSV field
ts_ms number (uint64) Unix ms (UTC) Reception timestamp at the anchor — milliseconds since epoch. timestamp_ms
anchor string bline-<SN>-<port> Identifier of the Bline anchor that observed the packet. SN = serial number, port = HCI index. anchor
mac string aabbccddeeff BLE source address of the sender (public or random, possibly RPI) — without colons, 12 hex characters in a row. mac
rssi number (int) dBm Received signal strength (typ. −30 … −100). rssi
connectable boolean true / false true = connectable advertisement, false = non-connectable. conn (C/N)
adv_hex string 0…62 hex characters (≤ 31 bytes) Complete advertising PDU as lowercase hex — see BLE/taskit BLE Manufacturer Advertisement. adv_hex
node_name string | null UTF-8 Node name (complete local name from scan response, or assigned via configuration). null if unknown. node_name

Notes - One JSON object per line (NDJSON), line ending \n. No enclosing array, no comma between lines. - Field order in JSON objects is not guaranteed — parsers must access fields by name, not by position (unlike the CSV format). - rssi and ts_ms are native JSON numbers, not strings – no cast needed when parsing. - connectable is a boolean, not a single character like conn in the CSV. - Multiple anchors seeing the same packet → multiple objects with identical mac + adv_hex, but different anchor, rssi, and possibly ts_ms.

2. Example Object

{"ts_ms": 1779364221617, "anchor": "bline-80346594359-01", "mac": "404cca5bbf1e", "rssi": -80, "connectable": true, "adv_hex": "0201061bff7b0120000c8e404cca5bbf1e335f676173330000000000208044", "node_name": "taskit_m2go.Mems"}
Field Value Meaning
ts_ms 1779364221617 2026-05-22 11:50:21.617 UTC
anchor "bline-80346594359-01" Bline anchor SN 80346594359, HCI index 01
mac "404cca5bbf1e" BLE address of the sensor
rssi -80 −80 dBm (medium distance)
connectable true Connectable
adv_hex "0201061bff7b0120000c8e404cca5bbf1e335f676173330000000000208044" 31-byte advertising payload
node_name "taskit_m2go.Mems" M2Go node with MEMS sensor

3. Decoding adv_hex (Example)

Identical to the CSV format — adv_hex is the same hex string in both formats. Applying the table from BLE/taskit BLE Manufacturer Advertisement to the 31 bytes:

Byte Hex Section Meaning
1–3 02 01 06 Flags AD Length 2, type 0x01 (flags), value 0x06 = LE General Discoverable + BR/EDR Not Supported
4 1b MSD AD Length = 27 bytes (sensor with MAC)
5 ff MSD AD AD type Manufacturer Specific Data
6–7 7b 01 MSD AD Company ID 0x017B (taskit, little endian)
8 20 Type byte 0x20 = Taskit Sensor with MAC
9 00 Version Protocol version 0
10 0c Hardware ID 12 — taskit hardware (here, the M2Go's MEMS sensor)
11 8e SenML Unit ID 142 — manufacturer-specific unit
12–17 40 4c ca 5b bf 1e MAC 404cca5bbf1e (identical to the mac field)
18–27 33 5f 67 61 73 33 00 00 00 00 00 Name (ASCII, zero-padded) "3_gas3"
28–31 00 20 80 44 Value IEEE 754 float (LE) → 1024.25

Float endianness: bytes 28–31 = 00 20 80 44 are read as little endian → 0x44802000 → 1024.25. A big-endian interpretation 0x00208044 would produce a subnormal value (~3·10⁻³⁹) and is therefore ruled out.

4. Parser Sketch (Pseudo)

import json, struct

def parse_line(line: str) -> dict:
    obj = json.loads(line.rstrip("\n"))
    raw = bytes.fromhex(obj["adv_hex"])
    return {
        "ts_ms":   obj["ts_ms"],
        "anchor":  obj["anchor"],
        "mac":     obj["mac"],
        "rssi":    obj["rssi"],
        "conn":    obj["connectable"],
        "type":    raw[7],          # 0x02 / 0x20 / 0x30 / 0x40 / 0x50
        "version": raw[8],
        "hw_id":   raw[9],
        "unit_id": raw[10],
        "value":   struct.unpack("<f", raw[27:31])[0],   # LE float
        "name":    obj.get("node_name"),
    }

No manual split handling needed — json.loads handles type conversion (number, bool, string, null) automatically. obj.get("node_name") returns None if the field is missing or null.

5. Special Cases

Situation Effect in JSON
Sender without scan response node_name is null (instead of an empty field with a trailing comma in the CSV).
RPI frame (Type = 0x30) mac contains the random address of the current interval; the physical MAC cannot be derived.
Anchor beacon (Type = 0x40) node_name contains the anchor name; the Value field carries no sensor measurement.
Text frame (Type = 0x50) Bytes 12–31 contain ASCII; the float interpretation does not apply.
Apple iBeacon-compatible (Type = 0x02) Bytes 26–31 follow the Apple layout (major / minor / RSSI calibration).

6. CSV vs. JSON Comparison

Aspect CSV format JSON format
Framing 1 line = 1 comma list 1 line = 1 JSON object (NDJSON)
Field access by fixed position by field name
connectable single character C/N boolean true/false
Numbers as string in text native JSON number
Missing name empty field, line ends with , node_name: null
Payload size more compact somewhat larger (field names repeat per line)
Robustness with additional fields requires format change new fields can be ignored, backward-compatible