BACKGROUND
I’ve often wondered what would happen if my video camera footage was ever used in a court case, and the question of time stamp accuracy came up. Would I be required to provide a statement or testimony on the accuracy of the time stamps on the video overlay and what source of time is used?
CONFIG
1. GPS+PPS NTP Server on my local LAN
2. NIST authenticated and USNO sources as backup
3. Firewall rule to redirect all outbound NTP requests to my local NTP server.
RESULTS
1. GPS+PPS NTP server ~0.5 sec from NIST and USNO internet sources.
2. GPS+PPS 0.000 msec offset and 0.003 msec jitter
3. Used Atomic Clock iOS app, synced to time.nist.gov, to display time to camera and recorded video feed. Determined time stamp overlay is approx 0.390 seconds behind the time displayed by the app.
I’ve often wondered what would happen if my video camera footage was ever used in a court case, and the question of time stamp accuracy came up. Would I be required to provide a statement or testimony on the accuracy of the time stamps on the video overlay and what source of time is used?
CONFIG
1. GPS+PPS NTP Server on my local LAN
2. NIST authenticated and USNO sources as backup
3. Firewall rule to redirect all outbound NTP requests to my local NTP server.
RESULTS
1. GPS+PPS NTP server ~0.5 sec from NIST and USNO internet sources.
2. GPS+PPS 0.000 msec offset and 0.003 msec jitter
remote refid st t when poll reach delay offset jitter==============================================================================o127.127.20.0 .GPS. 0 l 6 8 377 0.000 +0.000 0.003+132.163.97.5 .NIST. 1 u 66 64 377 49.977 +0.636 0.6+132.163.96.5 .NIST. 1 u 50 64 377 49.583 +0.516 0.319+129.6.15.32 .NIST. 1 u 56 64 377 42.232 -0.286 0.3393. Used Atomic Clock iOS app, synced to time.nist.gov, to display time to camera and recorded video feed. Determined time stamp overlay is approx 0.390 seconds behind the time displayed by the app.
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