mirror of
https://github.com/DJ2LS/FreeDATA
synced 2024-05-14 08:04:33 +00:00
141 lines
No EOL
2.6 KiB
Markdown
141 lines
No EOL
2.6 KiB
Markdown
# FreeDATA - Protocols
|
|
|
|
## ARQ Sessions
|
|
An ARQ Session represents a reliable data transmission session from a sending station (A) to a receiving station (B). It uses automatic repeat request on top of different codec2 modes according to the transmission channel conditions.
|
|
|
|
So lets say A wants to send some data to B. A typical scenario would be like this:
|
|
|
|
```
|
|
ISS->(1)IRS:<datac13> OPEN_REQ(session id, origin, dest)
|
|
IRS->(1)ISS:<datac13> OPEN_ACK (session id, proto version, speed level, frames, snr)
|
|
|
|
ISS->(1)IRS:<datac13> INFO(id, total_bytes, total_crc)
|
|
IRS->(1)ISS:<datac13> INFO_ACK(id, total_crc)
|
|
|
|
ISS->(1)IRS:BURST (ID, offset, payload),(ID, offset, payload),(ID, offset, payload)
|
|
IRS->(1)ISS:BURST_ACK (ID, next_offset, speed level, frames, snr)
|
|
|
|
ISS-->(1)IRS:Lost BURST (total or part)
|
|
IRS->(1)ISS:BURST_NACK (ID, next_offset, speed level, frames, snr)
|
|
|
|
ISS->(1)IRS:BURST (ID, offset, payload),(ID, offset, payload),(ID, offset, payload)
|
|
IRS->(1)ISS:DATA ACK NACK (ID, next_offset, speed level, frames, snr)
|
|
```
|
|
|
|
|
|
### Frame details
|
|
|
|
|
|
#### SESSION_OPEN_REQ
|
|
|
|
ISS sends this first
|
|
|
|
DATAC13 Mode (12 bytes)
|
|
|
|
|field|bytes|
|
|
|-|-|
|
|
|session id|1|
|
|
|origin|6|
|
|
|destination_crc|3|
|
|
|
|
|
|
#### SESSION_OPEN_ACK
|
|
|
|
Sent by the IRS in response to a SESSION_OPEN_REQ
|
|
|
|
DATAC13 Mode (12 bytes)
|
|
|
|
|field|bytes|
|
|
|-|-|
|
|
|session id|1|
|
|
|origin|6|
|
|
|destination_crc|3|
|
|
|protocol version|1|
|
|
|snr|1|
|
|
|
|
|
|
#### SESSION_INFO
|
|
|
|
ISS sends this in response to a SESSION_OPEN_ACK
|
|
|
|
DATAC13 Mode (12 bytes)
|
|
|
|
|field|bytes|
|
|
|-|-|
|
|
|session id|1|
|
|
|total bytes|4|
|
|
|total crc|4|
|
|
|snr|1|
|
|
|
|
|
|
#### SESSION_INFO_ACK
|
|
|
|
IRS sends this in response to a SESSION_INFO
|
|
|
|
DATAC13 Mode (12 bytes)
|
|
|
|
|field|bytes|
|
|
|-|-|
|
|
|session id|1|
|
|
|total crc|4|
|
|
|snr|1|
|
|
|speed level|1|
|
|
|frames per burst|1|
|
|
|
|
|
|
#### Data Burst
|
|
|
|
ISS sends this to send data to IRS
|
|
|
|
Mode according to handshake speed level
|
|
|
|
Frames per burst according to handshake
|
|
|
|
##### Modulation
|
|
Each burst is composed of frames_per_burst frames:
|
|
|
|
|preamble|f1|f2|f3|...|postamble|
|
|
|
|
##### Each data frame
|
|
|
|
|field|bytes|
|
|
|-|-|
|
|
|session id|1|
|
|
|offset|4|
|
|
|payload|(the remaining payload length)|
|
|
|
|
|
|
#### DATA_BURST_ACK
|
|
|
|
Sent by the IRS following successful decoding of burst.
|
|
|
|
|field|bytes|
|
|
|-|-|
|
|
|session id|1|
|
|
|next offset|4|
|
|
|next speed level|1|
|
|
|next frames per burst|1|
|
|
|snr|1|
|
|
|
|
|
|
#### DATA_BURST_NACK
|
|
|
|
Sent by the IRS following unsuccessful decoding of burst or timeout.
|
|
|
|
|field|bytes|
|
|
|-|-|
|
|
|session id|1|
|
|
|next offset|4|
|
|
|next speed level|1|
|
|
|next frames per burst|1|
|
|
|snr|1|
|
|
|
|
#### DATA ACK NACK
|
|
|
|
Sent by the IRS after receiving data with a state information.
|
|
|
|
| field |bytes|
|
|
|------------|-|
|
|
| session id |1|
|
|
| state |1|
|
|
| snr |1| |