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Added link stats packet #33

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Added link stats packet #33

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4fb4d23
Added link stats packet
David-OConnor Jun 9, 2023
4726e55
Fixed error
David-OConnor Jun 9, 2023
da39c06
Change to LQ and RSSI descriptions
David-OConnor Jun 21, 2023
d84dd8f
More updates
David-OConnor Jun 21, 2023
21fc264
Added uplink active antenna
David-OConnor Jun 21, 2023
39f5713
Update
David-OConnor Jun 21, 2023
fbbf89d
typo
David-OConnor Jun 22, 2023
6cfa8b9
Added downlink rssi 2
David-OConnor Jun 22, 2023
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39 changes: 39 additions & 0 deletions dronecan/sensors/rc/1141.RCLinkStats.uavcan
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Original file line number Diff line number Diff line change
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#
# This definition describes metadata and statistics for a RF control link.
# It provides information regarding a link's signal quality, as well as transmitter
# power, and antenna information. It accomodates single-radio, and dual-radio
# link architectures. It provides information for both uplink (control unit to airborne
# receiver), and downlink (airborne receiver to control unit) data.
#

uint8 STATUS_RSSI_VALID = 1 # RSSI field is valid

# Uplink - received signal strength, in decibel-milliwatts (RSSI dBm) for antennas 1 and 2 respectively.
# Ranges from # -255 to 0. (An integer value of 100 means RSSI is -100dBm)
uint8 uplink_rssi_1
uint8 uplink_rssi_2

# Link quality, on a scale from 1 to 255. Is a proxy for packet loss. 0 means data is unavailable. 1 and 255 are mapped to 0% and 100% of packets received.
uint8 uplink_link_quality
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@hamishwillee hamishwillee Jun 22, 2023 •
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This version would align with MAVLink better.

  • MAVLink uses 0 as a proxy for invalid by preference, and max field values if "0" is meaningful number for the field., In this case 0 is valid, so suggest we swap around.
  • Usually it is easier for users parsing the data to supply percentage data as a 0..100 range. The only reason to use the full range is if you need finer resolution, which I do not believe is the case here.
  • Have no discussed the words with OllieW yet.
Suggested change
# Link quality, on a scale from 1 to 255. Is a proxy for packet loss. 0 means data is unavailable. 1 and 255 are mapped to 0% and 100% of packets received.
uint8 uplink_link_quality
# Link quality, as a percentage of valid packets received over some time period [0..100]. 256 means data is unavailable.
uint8 uplink_link_quality

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@David-OConnor Can we swap to this pattern?


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# Signal-to-noise ratio.
int8 uplink_snr

# This is an implementation-specific enum. May represent the OTA protocol used,
# and transmission rate.
uint8 rf_mode

# This is an implementation-specific enum describing the current transmitter nominal
# power level.
uint8 uplink_tx_power

# Statistics for downlink data, ie telemetry. See their respective `uplink` fields for
# descriptions.
uint8 downlink_rssi
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uint8 downlink_link_quality
int8 downlink_snr

# Active antenna on transmitter and receiver. Example: 1 for antenna 1, and 2 for antenna 2.
# Not applicable for single-antenna links.
uint8 tx_active_antenna
uint8 rx_active_antenna
Comment on lines +37 to +40
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Is this the uplink or the downlink? Or is this a typo - ie. do you mean uplink_tx_active_antenna and uplink_rx_active_antenna or something else?

From discussion on MAVLink issue:

a unit which has two antenna may or may not split them into one is for Tx and the other one for Rx.
Usually, at least in nearly all cases I'm aware of, they both would be used to e.g. receive, which is when called receive diversity. Note that many bidirectional units are half-duplex, i.e. work as transmit-receive-transmit-receive-.... so that both antenna can be used for receiving one frame at the same time.
I guess the system you have in mind is a system there two over-the-air channels/frequencies are used in parallel, in a full-duplex sense, there one channel/frequency is for transmission in one direction and the other for transmission in the other direction. As said, essentially all systems I'm aware of are of the half-duplex nature.
Anyway, also the full-duplex case can be represented by the suggested fields.

My assumption is therefore that you need to be able to get info for antenna usage on both uplink and downlink.
(Note, Ollie uses Rx for air unit, and Tx for ground unit).

I'm still confused by the intent here - i.e. if you have bidirectional data, and the antenna both receive and both send in a cycle how would you represent it. I mean you'd have to show "no rx antenna and both 1 and 2 on the tx, then visa versa).
Also if it is switching, how useful is that?