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update network stack documentation;

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pull/121/merge
Bryan Biedenkapp 3 weeks ago
parent 9a31910526
commit f7023e2965
1 changed files with 95 additions and 153 deletions
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docs/TN.1000 - Network Stack Technical Documentation.md
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@ -1177,25 +1177,21 @@ The DMR network packet uses the TAG_DMR_DATA identifier (`0x444D5244` or ASCII "
Complete Packet (87 bytes):
90 FE 00 2A 00 00 1F 40 00 00 4E 20 | A3 5C 00 00 12 34 56 78 00 00 4E 20 00 23 00 00 00 00 00 00 | 44 4D 52 44 05 00 00 AA BB 00 CC DD 00 00 00 01 02 00 00 00 00 [33 bytes DMR data...] 00 7F
├─────────── RTP (12) ───────────┤ ├──────────────────────── FNE (20) ────────────────────────┤ ├────────────────────────────────── DMR (55) ────────────────────────────────┤
├─────────── RTP (12) ───────────┤ ├──────────────────────── FNE (20) ────────────────────────┤ ├────────────────────────────────── DMR (55) ─────────────────────────────────────────────────┤
DMR Payload breakdown:
44 4D 52 44 05 00 00 AA BB 00 CC DD 00 00 00 01 02 00 00 00 00 [33 bytes DMR frame...] 00 7F
│ │ │ │ │ │ │ │ │ │ │ │ │ │
│ │ │ │ │ │ │ │ │ │ │ └─[Reserved 4]──┤ │
│ │ │ │ │ │ │ │ │ │ └─ Slot/FLCO/DataType: 0x02
│ │ │ │ │ │ │ │ │ └──── Control: 0x01
│ │ │ │ │ │ │ └─[Reserved 3]
│ │ │ │ │ └─[DestID 3rd byte]──── Dest ID: 0x00CCDD (52445)
│ │ │ │ └─[DestID 2nd byte]
│ │ │ └─[DestID 1st byte]
│ │ └─[SrcID 3rd byte]────────────────── Src ID: 0x0000AABB (43707)
│ └─[SrcID 2nd byte]
│ └─[SrcID 1st byte]
│ └─────────────────────────────────────── Sequence: 5
└──────────────────────────────────────────────── Tag: "DMRD" (0x444D5244)
└─ (DMR frame at offset 20)──────────────── BER: 0x00
└─ RSSI: 0x7F (127)
44 4D 52 44 05 00 AA BB 00 CC DD 00 00 00 01 02 00 00 00 00 [33 bytes DMR frame...] 00 7F
│ │ │ │ │ │ │ │ │ │ │ │ │ │ │
│ │ │ │ │ │ │ │ │ │ │ └───────┴ Reserved │ │
│ │ │ │ │ │ │ │ │ │ └─────────── Slot/FLCO/DataType: 0x02 │ │
│ │ │ │ │ │ │ │ │ └────────────── Control: 0x01 │ │
│ │ │ │ │ │ │ └─────┴───────────────── Reserved │ │
│ │ │ │ │ └─────┴─────────────────────────── Dest ID: 0x00CCDD (52445)│ │
│ │ │ └─────┴──────────────────────────────────── Src ID: 0x00AABB (43707) │ │
│ │ └───────────────────────────────────────────── Sequence: 5 │ │
└────────┴──────────────────────────────────────────────── Tag: "DMRD" (0x444D5244) │ │
└─── BER: 0x00
└─ RSSI: 0x7F (127)
```
#### P25 Message Formats
@ -1221,6 +1217,61 @@ bool BaseNetwork::writeP25LDU1(const p25::lc::LC& control,
}
```
**P25 Message Header Structure (24 bytes):**
**Control Byte (`CONTROL_BYTE`) Flags:**
The Control Byte at offset 14 is a bitmask defined by `enum CONTROL_BYTE` in `BaseNetwork.h`. It is passed as the `controlByte` parameter to `writeP25TDU()` and stored in the TDU packet to signal in-band network control to the receiving endpoint. Multiple flags may be OR'd together. A value of `0x00` means no control operation is requested.
| Bit Mask | Name | Description |
|----------|------|-------------|
| `0x80` | `NET_CTRL_GRANT_DEMAND` | Grant demand — peer is requesting a channel grant for an ongoing call |
| `0x40` | `NET_CTRL_GRANT_DENIAL` | Grant denial — FNE is denying a channel grant request |
| `0x20` | `NET_CTRL_SWITCH_OVER` | Call source RID switch over — the originating radio ID changed mid-call |
| `0x08` | `NET_CTRL_GRANT_ENCRYPT` | Encrypted grant — the associated channel grant is for an encrypted call |
| `0x01` | `NET_CTRL_U2U` | Unit-to-unit — this is a unit-to-unit (private) call, not a group call |
**P25 Message Header Structure (24 bytes):**
The message header created by `createP25_MessageHdr()` contains:
| Offset | Length | Field | Description |
|--------|--------|-------|-------------|
| 0-3 | 4 | P25 Tag | "P25D" (0x50323544) |
| 4 | 1 | LCO | Link Control Opcode |
| 5-7 | 3 | Source ID | Calling radio ID |
| 8-10 | 3 | Destination ID | Target talkgroup/radio |
| 11-12 | 2 | System ID | Site system ID |
| 13 | 1 | Reserved | Reserved (0x00) |
| 14 | 1 | Control Byte | Network control flags (`CONTROL_BYTE` bitmask) |
| 15 | 1 | MFId | Manufacturer ID |
| 16-18 | 3 | Network ID | FNE network/WACN ID |
| 19 | 1 | Slot / Reserved | Bit 7: slot number; bits 4–0: P2 DUID (if Phase 2, else 0x00) |
| 20 | 1 | LSD1 | Low Speed Data byte 1 |
| 21 | 1 | LSD2 | Low Speed Data byte 2 |
| 22 | 1 | DUID | Data Unit ID (0x05 LDU1, 0x0A LDU2, 0x03 TDU, 0x07 TSDU, 0x0F TDULC) |
| 23 | 1 | Frame Length | Payload data length in bytes (0x00 for LDU1/LDU2; set for TDU/TSDU/TDULC) |
```
P25 Message Header (first 24 bytes):
50 32 35 44 00 00 AA BB 00 CC DD 00 01 00 00 00 00 00 01 00 00 00 05 00
│ │ │ │ │ │ │ │ │ │ │ │ │ │ │ │ │ │ │
│ │ │ │ │ │ │ │ │ │ │ │ │ │ │ │ │ │ └─────── Frame Length: 0x00
│ │ │ │ │ │ │ │ │ │ │ │ │ │ │ │ │ └────────── DUID: 0x05 (LDU1)
│ │ │ │ │ │ │ │ │ │ │ │ │ │ │ │ └───────────── LSD2: 0x00
│ │ │ │ │ │ │ │ │ │ │ │ │ │ │ └──────────────── LSD1: 0x00
│ │ │ │ │ │ │ │ │ │ │ │ │ │ └─────────────────── Slot/Reserved: 0x00
│ │ │ │ │ │ │ │ │ │ │ │ └─────┴────────────────────── Net ID: 0x000001 (1)
│ │ │ │ │ │ │ │ │ │ │ └─────────────────────────────── MFId: 0x00 (Standard)
│ │ │ │ │ │ │ │ │ │ └────────────────────────────────── Control Byte: 0x00
│ │ │ │ │ │ │ │ │ └───────────────────────────────────── Reserved: 0x00
│ │ │ │ │ │ │ └──┴──────────────────────────────────────── Sys ID: 0x0001 (1)
│ │ │ │ │ └─────┴────────────────────────────────────────────── Dst ID: 0x00CCDD (52445)
│ │ │ └─────┴─────────────────────────────────────────────────────── Src ID: 0x0000AABB (43707)
│ │ └──────────────────────────────────────────────────────────────── LCO: 0x00 (Group Voice)
└────────┴─────────────────────────────────────────────────────────────────── Tag: "P25D" (0x50323544)
```
**P25 LDU1 Packet Structure:**
The P25 LDU1 message uses DFSI encoding to pack 9 IMBE voice frames with link control data. The total size is 193 bytes (`P25_LDU1_PACKET_LENGTH = 193U`), which includes:
@ -1245,25 +1296,6 @@ The P25 LDU1 message uses DFSI encoding to pack 9 IMBE voice frames with link co
**Total P25 LDU1 Size:** 193 bytes (`P25_LDU1_PACKET_LENGTH`)
**P25 Message Header Structure (24 bytes):**
The message header created by `createP25_MessageHdr()` contains:
| Offset | Length | Field | Description |
|--------|--------|-------|-------------|
| 0 | 4 | P25 Tag | "P25D" (0x50323544) |
| 4 | 1 | DUID | Data Unit ID (e.g., 0x05 for LDU1, 0x0A for LDU2) |
| 5 | 1 | Control Byte | Network control flags |
| 6 | 1 | LCO | Link Control Opcode |
| 7 | 1 | MFId | Manufacturer ID |
| 8-10 | 3 | Source ID | Calling radio ID |
| 11-13 | 3 | Destination ID | Target (talkgroup/radio) |
| 14-16 | 3 | Reserved | Reserved bytes |
| 17 | 1 | RSSI | Signal strength |
| 18 | 1 | BER | Bit error rate |
| 19-22 | 4 | Reserved | Reserved bytes |
| 23 | 1 | Count | Total payload size |
**DFSI Encoding Details:**
The Digital Fixed Station Interface (DFSI) encoding is a TIA-102.BAHA standard for transporting P25 voice over IP. Each IMBE voice frame (11 bytes of raw IMBE data) is encoded using the `p25::dfsi::LC::encodeLDU1()` method with a specific frame type:
@ -1285,21 +1317,7 @@ The DFSI frames embed the Link Control (LC) and Low Speed Data (LSD) information
```
[RTP: 12 bytes] [FNE: 20 bytes] [P25 LDU1 Payload: 193 bytes]
P25 Message Header (first 24 bytes):
50 32 35 44 05 00 03 90 00 00 AA BB 00 CC DD EE 00 00 00 7F 00 00 00 00 A9
│ │ │ │ │ │ │ │ │ │ │ │ │ │ │ │ │ │
│ │ │ │ │ │ │ │ │ │ │ │ │ │ │ │ │ └─ Count: 0xA9 (169)
│ │ │ │ │ │ │ │ │ │ │ │ │ └──┴──┴──┴──── Reserved
│ │ │ │ │ │ │ │ │ │ │ │ └────────────────── BER: 0x00
│ │ │ │ │ │ │ │ │ │ │ └───────────────────── RSSI: 0x7F (127)
│ │ │ │ │ │ │ │ │ └──┴──┴────────────────────── Reserved
│ │ │ │ │ │ │ └──┴───────────────────────────────────── Dest ID: 0x00CCDDEE (13492718)
│ │ │ │ │ │ └───────────────────────────────────────────────── Src ID: 0x0000AABB (43707)
│ │ │ │ │ └──────────────────────────────────────────────────── MFId: 0x90 (Standard)
│ │ │ │ └─────────────────────────────────────────────────────── LCO: 0x03 (Group Voice Channel User)
│ │ │ └────────────────────────────────────────────────────────── Control: 0x00
│ │ └───────────────────────────────────────────────────────────── DUID: 0x05 (LDU1)
└────────┴──────────────────────────────────────────────────────────────── Tag: "P25D" (0x50323544)
[P25 Message Header 24 bytes]
DFSI Voice Frames (offsets 24-177):
Offset 24: [22 bytes] LDU1_VOICE1 (DFSI frame type 0x62)
@ -1323,7 +1341,7 @@ Additional Data (offsets 178-192):
- `MSG_HDR_SIZE = 24U`
- Total allocated size: 193 + 8 = 201 bytes
**LDU2 (Link Data Unit 2) with DFSI Encoding:**
**P25 LDU2 Packet Structure:**
LDU2 has a similar structure to LDU1 but uses different DFSI frame types and contains Encryption Sync (ESS) data instead of Link Control in frames 3-8. Total size is 181 bytes (`P25_LDU2_PACKET_LENGTH = 181U`).
@ -1358,56 +1376,23 @@ The TDU packet consists of:
**Total TDU Payload Size (after FNE):** 24 bytes (`MSG_HDR_SIZE = 24U`)
**Raw TDU Packet Example (hexadecimal):**
```
[RTP: 12 bytes] [FNE: 20 bytes] [P25 TSDU: 24 bytes]
Complete Packet (101 bytes):
90 FE 00 2A 00 00 1F 40 00 00 4E 20 | A3 5C 00 01 12 34 56 78 00 00 4E 20 00 45 00 00 00 00 00 00 | 50 32 35 44 07 00 00 90 00 00 AA BB 00 CC DD EE 00 00 00 7F 00 00 00 00 2D
├─────────── RTP (12) ────────────┤ ├────────────────────── FNE (20) ─────────────────────────┤ ├───────────────────────────────── P25 TSDU (24) ────────────────────────┤
```
**Constants:**
- `MSG_HDR_SIZE = 24U` (defined in `BaseNetwork.h`)
- `PACKET_PAD = 8U`
- Total allocated size: 24 + 8 = 32 bytes
- DUID value: `0x03` (TDU - Terminator Data Unit)
**P25 Message Header Structure (24 bytes):**
| Offset | Length | Field | Description |
|--------|--------|-------|-------------|
| 0-3 | 4 | P25 Tag | "P25D" (0x50323544) |
| 4 | 1 | DUID | 0x03 (TDU) |
| 5 | 1 | Control Byte | Network control flags (at offset 14 in buffer) |
| 6 | 1 | LCO | Link Control Opcode (from last transmission) |
| 7 | 1 | MFId | Manufacturer ID |
| 8-10 | 3 | Source ID | Radio ID that ended transmission |
| 11-13 | 3 | Destination ID | Target talkgroup/radio |
| 14-16 | 3 | Reserved | Reserved bytes |
| 17 | 1 | RSSI | Signal strength |
| 18 | 1 | BER | Bit error rate |
| 19-22 | 4 | Reserved | Reserved bytes |
| 23 | 1 | Count | 0x18 (24) - header size only, no payload follows |
**Raw TDU Packet Example (hexadecimal):**
```
[RTP Header: 12 bytes] [FNE Header: 20 bytes] [P25 Header: 24 bytes] [NO PAYLOAD]
Complete Packet (56 bytes):
90 FE 00 2A 00 00 1F 40 00 00 4E 20 | A3 5C 00 01 12 34 56 78 00 00 4E 20 00 18 00 00 00 00 00 00 | 50 32 35 44 03 00 03 90 00 00 AA BB 00 CC DD EE 00 00 00 7F 00 00 00 00 18
├─────────── RTP (12) ───────────┤ ├──────────────────────── FNE (20) ────────────────────────┤ ├──────────────────────── P25 (24) ─────────────────────────┤
P25 Message Header (NO PAYLOAD FOLLOWS):
50 32 35 44 03 00 03 90 00 00 AA BB 00 CC DD EE 00 00 00 7F 00 00 00 00 18
│ │ │ │ │ │ │ │ │ │ │ │ │ │ │ │ │ │
│ │ │ │ │ │ │ │ │ │ │ │ │ └──┴──┴──┴──┴─ Count: 0x18 (24) - header only
│ │ │ │ │ │ │ │ │ │ │ │ └────────────────── Reserved (4 bytes)
│ │ │ │ │ │ │ │ │ │ │ └───────────────────── BER: 0x00
│ │ │ │ │ │ │ │ │ │ └──────────────────────── RSSI: 0x7F (127)
│ │ │ │ │ │ │ │ │ └──┴──┴───────────────────── Reserved (3 bytes)
│ │ │ │ │ │ │ └──┴────────────────────────────────────── Dest ID: 0x00CCDDEE (13492718)
│ │ │ │ │ │ └────────────────────────────────────────────────── Src ID: 0x0000AABB (43707)
│ │ │ │ │ └───────────────────────────────────────────────────── MFId: 0x90 (Standard)
│ │ │ │ └──────────────────────────────────────────────────────── LCO: 0x03 (Group Voice)
│ │ │ └─────────────────────────────────────────────────────────── Control: 0x00
│ │ └────────────────────────────────────────────────────────────── DUID: 0x03 (TDU)
└────────┴───────────────────────────────────────────────────────────────── Tag: "P25D" (0x50323544)
Total packet ends at byte 56 - no additional payload bytes after the P25 header.
```
**Important Note:**
@ -1463,28 +1448,12 @@ The 45-byte TSDU frame data at offset 24 is **transmitted in its raw over-the-ai
Complete Packet (101 bytes):
90 FE 00 2A 00 00 1F 40 00 00 4E 20 | A3 5C 00 01 12 34 56 78 00 00 4E 20 00 45 00 00 00 00 00 00 | 50 32 35 44 07 00 00 90 00 00 AA BB 00 CC DD EE 00 00 00 7F 00 00 00 00 2D [45 bytes raw TSDU frame...]
├─────────── RTP (12) ───────────┤ ├──────────────────────── FNE (20) ────────────────────────┤ ├───────────────────────────────── P25 TSDU (69) ────────────────────────────────┤
TSDU Message Header (24 bytes):
50 32 35 44 07 00 00 90 00 00 AA BB 00 CC DD EE 00 00 00 7F 00 00 00 00 2D
│ │ │ │ │ │ │ │ │ │ │ │ │ │ │ │ │ │
│ │ │ │ │ │ │ │ │ │ │ │ │ └──┴──┴──┴──┴─ Count: 0x2D (45)
│ │ │ │ │ │ │ │ │ │ │ │ └────────────────── Reserved
│ │ │ │ │ │ │ │ │ │ │ └───────────────────── BER: 0x00
│ │ │ │ │ │ │ │ │ │ └──────────────────────── RSSI: 0x7F (127)
│ │ │ │ │ │ │ │ │ └──┴──┴───────────────────── Reserved
│ │ │ │ │ │ │ └──┴────────────────────────────────────── Dest ID: 0x00CCDDEE (13492718)
│ │ │ │ │ │ └────────────────────────────────────────────────── Src ID: 0x0000AABB (43707)
│ │ │ │ │ └───────────────────────────────────────────────────── MFId: 0x90 (Standard)
│ │ │ │ └──────────────────────────────────────────────────────── LCO: 0x00 (not applicable for TSDU)
│ │ │ └─────────────────────────────────────────────────────────── Control: 0x00
│ │ └────────────────────────────────────────────────────────────── DUID: 0x07 (TSDU)
└────────┴───────────────────────────────────────────────────────────────── Tag: "P25D" (0x50323544)
├─────────── RTP (12) ────────────┤ ├──────────────────────── FNE (20) ───────────────────────┤ ├───────────────────────────────── P25 TSDU (69) ─────────────────────────────────────────────────────┤
TSDU Frame Data (45 bytes starting at offset 24):
55 75 F7 FF 5D 7F [NID: 2 bytes] [TSBK: 25 bytes FEC encoded] [Status: 12 bytes]
│ │ └────────────┴────────────────────┴──────────────────────── Raw over-the-air P25 TSDU frame
└──────────────┴────────────────────────────────────────────────────────────── Frame Sync pattern
└──────────────┴───────────────────────────────────────────────────────────── Frame Sync pattern
```
**TSDU Content Types:**
@ -1544,28 +1513,12 @@ The 54-byte TDULC frame data at offset 24 is **transmitted in its raw over-the-a
Complete Packet (110 bytes):
90 FE 00 2A 00 00 1F 40 00 00 4E 20 | A3 5C 00 01 12 34 56 78 00 00 4E 20 00 4E 00 00 00 00 00 00 | 50 32 35 44 0F 00 03 90 00 00 AA BB 00 CC DD EE 00 00 00 7F 00 00 00 00 36 [54 bytes raw TDULC frame...]
├─────────── RTP (12) ───────────┤ ├──────────────────────── FNE (20) ────────────────────────┤ ├──────────────────────────────── P25 TDULC (78) ─────────────────────────────────┤
TDULC Message Header (24 bytes):
50 32 35 44 0F 00 03 90 00 00 AA BB 00 CC DD EE 00 00 00 7F 00 00 00 00 36
│ │ │ │ │ │ │ │ │ │ │ │ │ │ │ │ │ │
│ │ │ │ │ │ │ │ │ │ │ │ │ └──┴──┴──┴──┴─ Count: 0x36 (54)
│ │ │ │ │ │ │ │ │ │ │ │ └────────────────── Reserved
│ │ │ │ │ │ │ │ │ │ │ └───────────────────── BER: 0x00
│ │ │ │ │ │ │ │ │ │ └──────────────────────── RSSI: 0x7F (127)
│ │ │ │ │ │ │ │ │ └──┴──┴───────────────────── Reserved
│ │ │ │ │ │ │ └──┴────────────────────────────────────── Dest ID: 0x00CCDDEE (13492718)
│ │ │ │ │ │ └────────────────────────────────────────────────── Src ID: 0x0000AABB (43707)
│ │ │ │ │ └───────────────────────────────────────────────────── MFId: 0x90 (Standard)
│ │ │ │ └──────────────────────────────────────────────────────── LCO: 0x03 (Group Voice)
│ │ │ └─────────────────────────────────────────────────────────── Control: 0x00
│ │ └────────────────────────────────────────────────────────────── DUID: 0x0F (TDULC)
└────────┴───────────────────────────────────────────────────────────────── Tag: "P25D" (0x50323544)
├─────────── RTP (12) ────────────┤ ├──────────────────────── FNE (20) ───────────────────────┤ ├──────────────────────────────── P25 TDULC (78) ──────────────────────────────────────────────────────┤
TDULC Frame Data (54 bytes starting at offset 24):
55 75 F7 FF 5D 7F [NID: 2 bytes] [LC: 36 bytes FEC encoded] [Status: 10 bytes]
│ │ └────────────┴──────────────────────┴─────────────────────── Raw over-the-air P25 TDULC frame
└──────────────┴──────────────────────────────────────────────────────────────── Frame Sync pattern
└──────────────┴────────────────────────────────────────────────────────────── Frame Sync pattern
```
**TDULC Link Control Content:**
@ -1639,10 +1592,6 @@ The encapsulated Phase 2 format is fixed-length:
```
[RTP: 12 bytes] [FNE: 20 bytes] [P25 Phase 2: 66 bytes]
Complete Packet (98 bytes):
[RTP 12] [FNE 20] [P25 header 24 with slot/DUID in byte 19] [40 bytes raw P25 P2 payload] [packet pad]
├─────────── RTP (12) ───────────┤ ├──────────────────────── FNE (20) ────────────────────────┤ ├──────────────────────────── P25 P2 (66) ────────────────────────────┤
P25 Phase 2 payload breakdown:
"P25D" | common P25 header fields | controlByte @ 14 | slot/DUID @ 19 | count=0x40 @ 23 | 40 bytes raw P25 Phase 2 payload
```
@ -1700,25 +1649,19 @@ The NXDN network packet uses the TAG_NXDN_DATA identifier and includes the 48-by
Complete Packet (102 bytes):
90 FE 00 2A 00 00 1F 40 00 00 4E 20 | A3 5C 00 00 12 34 56 78 00 00 4E 20 00 46 00 00 00 00 00 00 | 4E 58 44 44 02 00 10 00 00 20 00 00 01 00 00 00 00 00 00 00 00 00 00 30 [48 bytes NXDN frame...]
├─────────── RTP (12) ───────────┤ ├──────────────────────── FNE (20) ────────────────────────┤ ├─────────────────────────────────── NXDN (70) ─────────────────────────────────┤
├─────────── RTP (12) ────────────┤ ├──────────────────────── FNE (20) ───────────────────────┤ ├─────────────────────────────────── NXDN (70) ────────────────────────────────────────────────┤
NXDN Payload breakdown:
4E 58 44 44 02 00 10 00 00 20 00 00 01 00 00 00 00 00 00 00 00 00 00 30 [48 bytes NXDN frame data...]
│ │ │ │ │ │ │ │ │ └──────────┴──────────┴─────┤
│ │ │ │ │ │ │ │ └───────────────────────────────── Group: 0x00 (private call)
│ │ │ │ │ │ │ └──────────────────────────────────── Control: 0x01
│ │ │ │ │ └─[Reserved 3]
│ │ │ │ └─[DestID 3rd byte]──────────────────────────────── Dest ID: 0x200000 (2097152)
│ │ │ └─[DestID 2nd byte]
│ │ └─[DestID 1st byte]
│ └─[SrcID 3rd byte]──────────────────────────────────────────────── Src ID: 0x001000 (4096)
│ └─[SrcID 2nd byte]
│ └─[SrcID 1st byte]
│ └──────────────────────────────────────────────────────────────── Msg Type: 0x02 (RTCH)
└───────────────────────────────────────────────────────────────────────── Tag: "NXDD" (0x4E584444)
└────────────────────────────────────────────────────────────────── Reserved (7 bytes)
└─ Count: 0x30 (48)
(NXDN frame at offset 24)
4E 58 44 44 02 00 10 00 00 20 00 00 00 00 00 01 00 00 00 00 00 00 00 30 [48 bytes NXDN frame data...]
│ │ │ │ │ │ │ │ │ │ │ │ │ └──── NXDN Count: 0x30 (48)
│ │ │ │ │ │ │ │ │ │ │ └──────────────────┴────── Reserved
│ │ │ │ │ │ │ │ │ │ └──────────────────────────── Group: 0x01 (group call)
│ │ │ │ │ │ │ │ │ └─────────────────────────────── Control: 0x00
│ │ │ │ │ │ │ └─────┴────────────────────────────────── Reserved
│ │ │ │ │ └─────┴─────────────────────────────────────────── Dest ID: 0x002000 (8192)
│ │ │ └─────┴──────────────────────────────────────────────────── Src ID: 0x001000 (4096)
│ │ └───────────────────────────────────────────────────────────── Msg Type: 0x02 (RTCH)
└────────┴──────────────────────────────────────────────────────────────── Tag: "NXDD" (0x4E584444)
```
**NXDN Message Types:**
@ -1781,7 +1724,6 @@ The analog audio packet uses the `TAG_ANALOG_DATA` identifier (`"ANOD"`) and con
Complete Packet (376 bytes):
[RTP 12] [FNE 20] ["ANOD" + header bytes + 320 bytes audio + 4 byte trailer]
├─────────── RTP (12) ───────────┤ ├──────────────────────── FNE (20) ────────────────────────┤ ├────────────────────────────────── Analog (344) ──────────────────────────────────┤
Analog Payload breakdown:
"ANOD" | Seq | SrcID | DstID | Reserved | Control | FrameType/Group | Reserved | 320 bytes audio | 4 byte trailer

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