Put the receiver on the clock
A dwell rule starts a clock of its own. If a vehicle must stay for five seconds, latency measured from first appearance includes those five seconds before the system even has an alert to send. Write down which instant triggers the rule, and keep the clip and the receipt record on the same time base.
Instrument a live replay
Set the sender and the receiving endpoint to UTC and record their clock offsets before and after the session. At the sender, log the UTC time of the first presented frame, then map the qualifying frame's presentation timestamp to that origin. At the receiver, log the first arrival of an alert with its stable ID. Preserve retries separately. For email, designate an instrumented inbox and record delivery there — a guard opening the mail is a different endpoint.
Subtract the qualifying UTC instant from receipt UTC and keep the raw differences in milliseconds, suspicious negatives included, for investigation. If the combined clock uncertainty exceeds 100 ms under this protocol, mark the session ineligible for delay and keep the reason. Report sample size, median and nearest-rank p95 beside the count of undelivered matched events. For p95, sort the observations and take position ceil(0.95 × n), counting from one. A single observation fills both summary positions and says little about the tail.
A clock that keeps advancing
M03 holds an image while its presentation timestamps keep advancing. Compare frames 9, 19 and 30 with F04 to check how a viewer handles repeated pictures. To measure loss of transport, interrupt the sender on a separate authorized run and capture its stop and restart times. An identical picture alone cannot establish a disconnected camera. L01 · Held sequence · Parent recording
Suppose the sender puts frame zero on the wire at 12:00:00.000 and the reference qualifies at source time 2.700 seconds. A first receipt stamped 12:00:03.400 then gives 700 ms of delivery delay under aligned clocks. Keep the receiver log line so a later reviewer can repeat the subtraction.
Keep uploads in their own column. Processing a file in ten seconds might meet an archive workflow's needs — but the file by itself carries no receipt timestamp from a live guard station.
Record identifiers · L01 · L02