A raddec is an open-standard representation of a radio decoding. This library provides functionality to manipulate any raddec as JSON and to convert to/from its binary representation.
raddec is a lightweight Node.js package that can run on resource-constrained edge devices as well as on powerful cloud servers and anything in between. It is core to reelyActive's Pareto Anywhere open source middleware suite and barnowl modules which interface with gateways, readers and APs across vendors and technologies.
Radio-Frequency IDentification (RFID), Real-Time Location Systems (RTLS) and M2M (Machine-to-Machine) communications share several key properties:
- transmitters transmit packets that may be received by one or more receivers
- each transmitter and receiver has its own identifier
- each received packet produces metadata including a timestamp and a Received Signal Strength Indication (RSSI)
For a broad range of applications, it is useful to identify, to locate and to collect ambient data from wireless devices, and this raddec library is developed with the intent of providing a protocol-agnostic means of representing and efficiently transferring such information across networks.
A raddec has two forms: an encoded form in which it has a strict binary representation, and a decoded form in which it typically has a less-restrictive JSON representation. The JSON representation is as follows:
{
transmitterId: "aabbccddeeff",
transmitterIdType: 2,
rssiSignature: [{
receiverId: "001bc50940810000",
receiverIdType: 1,
rssi: -69,
numberOfDecodings: 3
}],
packets: [ /* As hexadecimal strings */ ],
timestamp: 1343392496789
}See the reelyActive Developer's Cheatsheet for a developer-friendly overview of the raddec JSON.
This library provides functionality to encode a raddec, typically in anticipation of network transport to a destination computer, and to decode the same raddec, typically to facilitate manipulation and storage of the contained information.
const Raddec = require('raddec');
// The minimal raddec includes simply a transmitter identifier and type
let raddec = new Raddec({
transmitterId: "aa:bb:cc:dd:ee:ff",
transmitterIdType: Raddec.identifiers.TYPE_EUI48
});
// One or more decodings by receivers are typically added
raddec.addDecoding({
receiverId: "00-1b-c5-09-40-81-00-00",
receiverIdType: Raddec.identifiers.TYPE_EUI64,
rssi: -69
});
// Encoding results in a compact representation
let encoded = raddec.encodeAsHexString();
console.log(encoded);
// -> 10001702aabbccddeeff013a0101001bc509408100000b (23 bytes)
// Decoding restores a standard, easy-to-manipulate JSON object
raddec = new Raddec(encoded);
// A trim prunes any non-standard properties, adds timestamp if none present
raddec.trim();
console.log(raddec);
// {
// transmitterId: "aabbccddeeff",
// transmitterIdType: 2,
// rssiSignature: [{
// receiverId: "001bc50940810000",
// receiverIdType: 1,
// rssi: -69,
// numberOfDecodings: 1
// }],
// timestamp: 1343392496789
// }
// Flattening creates a JSON object suitable for storage/search/retrieval,
// with the default options shown below
let options = {
includePackets: true, // Applicable when packets property is present
includeRssiSignature: false, // Note that the rssiSignature is NOT flat
maxNumberOfReceivers: 15, // Only considered if
rssiThreshold: -127 // includeRssiSignature is true
};
let flattened = raddec.toFlattened(options);
console.log(flattened);
// {
// transmitterId: "aabbccddeeff",
// transmitterIdType: 2,
// receiverId: "001bc50940810000",
// receiverIdType: 1,
// rssi: -69,
// numberOfDecodings: 1,
// numberOfReceivers: 1,
// timestamp: 1343392496789
// }A raddec must include the following mandatory properties and may include any or all of the following optional properties.
A raddec includes the following three mandatory properties in both its encoded (binary) and decoded (JSON) form.
| Property | Type | Description |
|---|---|---|
| transmitterId | String | Hexadecimal string, lowercase, no separators |
| transmitterIdType | Number | Single byte (0-255) |
| rssiSignature | Array of Object | Ordered from strongest to weakest RSSI |
Each object in the rssiSignature array includes the following properties.
| Property | Type | Description |
|---|---|---|
| receiverId | String | Hexadecimal string, lowercase, no separators |
| receiverIdType | Number | Single byte (0-255) |
| rssi | Number | In dBm |
| numberOfDecodings | Number | Range of 1-255 (0 reserved) |
Any object in the rssiSignature array may also include the following property.
| Property | Type | Description |
|---|---|---|
| receiverAntenna | Number | Antenna ID or Antenna Port |
| aoa | Array of Number | Angle of Arrival: azimuth, elevation |
Note that the optional receiverAntenna and aoa properties are not included in the binary representation of a raddec: this is a limitation of v0.x of this library.
A raddec may include any or all of the following properties.
| Property | Type | Description |
|---|---|---|
| timestamp | Number | UNIX epoch (millisecond precision) |
| packets | Array of String | Hexadecimal string, lowercase, no duplicates |
| events | Array of Number | Index list of associated events |
| position | Array of Number | X, Y, Z coordinates |
When encoding a raddec, the optional properties to include must be explicitly specified, as the following example illustrates:
let encodedRaddec = raddec.encodeAsHexString({ includeTimestamp: true,
includePackets: true,
includeEvents: true,
includePosition: true });The raddec library is being developed with consideration for the following protocols/standards:
- Bluetooth Low Energy (broadcaster/observer roles)
- WiFi (ex: probe requests)
- RAIN RFID
- LPWAN (various standards)
- proprietary Active RFID (ex: reelyActive)
Both identifier types and event types are represented as numerical indexes for efficient manipulation and compact storage.
The identifier type indexes, which can be found in the identifiers.js file, are as follows:
| Index | Raddec.identifiers. | Description |
|---|---|---|
| 0 | TYPE_UNKNOWN | Unknown identifier type |
| 1 | TYPE_EUI64 | EUI-64 (used by reelyActive infrastructure) |
| 2 | TYPE_EUI48 | EUI-48 (WiFi, BLE public addresses) |
| 3 | TYPE_RND48 | Random 48-bit advertiser address (BLE) |
| 4 | TYPE_TID96 | 96-bit tag identifier (EPC Tag Data Standard) |
| 5 | TYPE_EPC96 | 96-bit Electronic Product Code (EPC) |
| 6 | TYPE_UUID128 | 128-bit Universally Unique Identifier (UUID) |
| 7 | TYPE_EURID32 | 32-bit EnOcean Unique Radio Identifier (EURID) |
| 8+ | - RESERVED - | Reserved for future use |
The event type indexes, which can be found in the events.js file, are as follows:
| Index | Raddec.events. | Description |
|---|---|---|
| 0 | APPEARANCE | First decoding of the transmitter in recent memory |
| 1 | DISPLACEMENT | Change of strongest receiver by transmitter |
| 2 | PACKETS | New packet payload received from transmitter |
| 3 | KEEPALIVE | Periodic update of transmitter's recent decoding(s) |
| 4 | DISAPPEARANCE | Transmitter no longer decoded by any receiver |
| 5-7 | - RESERVED - | Reserved for future use |
This library is currently in active development. Expect features to be added periodically. We recommend observing semantic versioning best practices for dependents should breaking changes be required. If you have an interest in using this library and/or have strong thoughts on its properties, kindly get in touch via our contact information.
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