Hey everyone,

I have done some advances with my PTP setup​ but still some fine enhancements 
need to be done. I am sending messages from one computer to another via the 
MK6c C-V2X devices. This devices have GPS and I am synchronising the computers 
to their respective Mk6c attached vie Ethernet.

Now the problem is, that when I send a message from Tx to Rx and measure the 
latency (attach timestamp to message and check in the Rx with the actual time), 
I get negative values and quite high also. They are all around -400-450 ms 
delay, which means that the computers are not getting the exact time from the 
gps in the MK6c devices.

I am executing the commands below in each device. Do you know if I can get a 
better synchronization in order to get the 4 elements in sync?

Thanks a lot in advance and have a nice weekend!

Bests,
Fede


Master-1 (Cohda Wireless MK6C with C-v2x qualcom modem and GPS integrated)


chronyc sources
210 Number of sources = 3
MS Name/IP address         Stratum Poll Reach LastRx Last sample
===============================================================================
#? KPPS                          0   2     0     -     +0ns[   +0ns] +/-    0ns
#? GNSS                          0   4     0     -     +0ns[   +0ns] +/-    0ns
^* qti-modem                     1   2   377     4   -173us[ -193us] +/- 1222us


cat ptp.cfg

[global]

tx_timestamp_timeout 10

step_threshold 1


ptp4l -A -i eth0 -m -f ptp.cfg

ptp4l[229.691]: selected /dev/ptp0 as PTP clock

ptp4l[229.693]: driver changed our HWTSTAMP options

ptp4l[229.693]: tx_type   1 not 1

ptp4l[229.693]: rx_filter 1 not 12

ptp4l[229.693]: port 1: INITIALIZING to LISTENING on INITIALIZE

ptp4l[229.693]: port 0: INITIALIZING to LISTENING on INITIALIZE

ptp4l[229.694]: port 1: link up

ptp4l[237.053]: port 1: LISTENING to MASTER on ANNOUNCE_RECEIPT_TIMEOUT_EXPIRES

ptp4l[237.053]: selected best master clock 04e548.fffe.23010c

ptp4l[237.053]: assuming the grand master role



Slave-1 (Ubuntu 20.04 Laptop)

cat ptp.conf
[global]
#clientOnly 1
delay_mechanism Auto
network_transport UDPv4
#time_stamping        hardware        # for the HW-timestamping slave
#time_stamping        software         # for the SW-timestamping slave
step_threshold 1.0
utc_offset 37
# make sure our slave clock is never elected as master
priority1 255
priority2 255
[enp0s25]

sudo ptp4l -f ptp.conf -m
ptp4l[7229.653]: selected /dev/ptp0 as PTP clock
ptp4l[7229.653]: port 1: INITIALIZING to LISTENING on INIT_COMPLETE
ptp4l[7229.653]: port 0: INITIALIZING to LISTENING on INIT_COMPLETE
ptp4l[7230.099]: port 1: new foreign master 04e548.fffe.23010c-1
ptp4l[7232.100]: selected best master clock 04e548.fffe.23010c
ptp4l[7232.100]: running in a temporal vortex
ptp4l[7232.100]: port 1: LISTENING to UNCALIBRATED on RS_SLAVE
ptp4l[7233.595]: master offset -494729050 s0 freq   +3191 path delay     36620
ptp4l[7234.100]: master offset -494729136 s1 freq   +3021 path delay     36620
ptp4l[7234.595]: master offset        -24 s2 freq   +2997 path delay     36620
ptp4l[7234.595]: port 1: UNCALIBRATED to SLAVE on MASTER_CLOCK_SELECTED
ptp4l[7235.100]: master offset        892 s2 freq   +3906 path delay     36620
ptp4l[7235.595]: master offset       1404 s2 freq   +4685 path delay     36620
ptp4l[7236.100]: master offset        357 s2 freq   +4059 path delay     36979

sudo phc2sys -s enp0s25 -O 0 -m
phc2sys[7239.599]: CLOCK_REALTIME phc offset -495721525 s0 freq   +1751 delay   
4109
phc2sys[7240.600]: CLOCK_REALTIME phc offset -495723277 s1 freq      +0 delay   
4377
phc2sys[7241.600]: CLOCK_REALTIME phc offset      -147 s2 freq    -147 delay   
4301
phc2sys[7242.601]: CLOCK_REALTIME phc offset       312 s2 freq    +268 delay   
4103
phc2sys[7243.601]: CLOCK_REALTIME phc offset       450 s2 freq    +500 delay   
4113
phc2sys[7244.601]: CLOCK_REALTIME phc offset       573 s2 freq    +758 delay   
4143
phc2sys[7245.601]: CLOCK_REALTIME phc offset      -246 s2 freq    +110 delay   
4146
phc2sys[7246.602]: CLOCK_REALTIME phc offset       -19 s2 freq    +264 delay   
4160
phc2sys[7247.602]: CLOCK_REALTIME phc offset       184 s2 freq    +461 delay   
4109
phc2sys[7248.602]: CLOCK_REALTIME phc offset       212 s2 freq    +544 delay   
4160
phc2sys[7249.603]: CLOCK_REALTIME phc offset      -554 s2 freq    -158 delay   
4125


Master 2 (Second Cohda Mk6c)

chronyc sources
210 Number of sources = 3
MS Name/IP address         Stratum Poll Reach LastRx Last sample
===============================================================================
#? KPPS                          0   2     0     -     +0ns[   +0ns] +/-    0ns
#? GNSS                          0   4     0     -     +0ns[   +0ns] +/-    0ns
^* qti-modem                     1   4   377     4   +112us[ +111us] +/- 1272us

cat ptp.cfg
[global]
tx_timestamp_timeout 10

ptp4l -A -i eth0 -m -f ptp.cfg
ptp4l[280.355]: selected /dev/ptp0 as PTP clock
ptp4l[280.357]: driver changed our HWTSTAMP options
ptp4l[280.357]: tx_type   1 not 1
ptp4l[280.357]: rx_filter 1 not 12
ptp4l[280.357]: port 1: INITIALIZING to LISTENING on INITIALIZE
ptp4l[280.357]: port 0: INITIALIZING to LISTENING on INITIALIZE
ptp4l[280.358]: port 1: link up
ptp4l[287.756]: port 1: LISTENING to MASTER on ANNOUNCE_RECEIPT_TIMEOUT_EXPIRES
ptp4l[287.757]: selected best master clock 04e548.fffe.230108
ptp4l[287.757]: assuming the grand master role


Slave-2 (Ubuntu 20.04 Laptop)

sudo ptp4l -f linuxptp.cfg -m
ptp4l[362997.494]: selected /dev/ptp0 as PTP clock
ptp4l[362997.494]: port 1 (enp0s31f6): INITIALIZING to LISTENING on 
INIT_COMPLETE
ptp4l[362997.494]: port 0 (/var/run/ptp4l): INITIALIZING to LISTENING on 
INIT_COMPLETE
ptp4l[362997.494]: port 0 (/var/run/ptp4lro): INITIALIZING to LISTENING on 
INIT_COMPLETE
ptp4l[362998.515]: port 1 (enp0s31f6): new foreign master 04e548.fffe.230108-1
ptp4l[363000.515]: selected best master clock 04e548.fffe.230108
ptp4l[363000.515]: running in a temporal vortex
ptp4l[363000.515]: port 1 (enp0s31f6): LISTENING to UNCALIBRATED on RS_SLAVE
ptp4l[363001.515]: master offset      -1841 s0 freq   +3112 path delay      8204
ptp4l[363001.942]: master offset      -1945 s2 freq   +2868 path delay      8204
ptp4l[363001.942]: port 1 (enp0s31f6): UNCALIBRATED to SLAVE on 
MASTER_CLOCK_SELECTED
ptp4l[363002.515]: master offset      -1622 s2 freq   +1246 path delay      8128
ptp4l[363002.942]: master offset       -814 s2 freq   +1568 path delay      8053
ptp4l[363003.515]: master offset        -93 s2 freq   +2045 path delay      8053

sudo phc2sys -s enp0s31f6 -O -0 -m
phc2sys[363001.918]: CLOCK_REALTIME phc offset        49 s0 freq   +3226 delay  
    0
phc2sys[363002.919]: CLOCK_REALTIME phc offset     -1011 s2 freq   +2167 delay  
    0
phc2sys[363003.919]: CLOCK_REALTIME phc offset     -1263 s2 freq    +904 delay  
    0
phc2sys[363004.920]: CLOCK_REALTIME phc offset       527 s2 freq   +2315 delay  
    0
phc2sys[363005.920]: CLOCK_REALTIME phc offset      1450 s2 freq   +3396 delay  
    0
phc2sys[363006.920]: CLOCK_REALTIME phc offset      1528 s2 freq   +3909 delay  
    0
phc2sys[363007.920]: CLOCK_REALTIME phc offset       896 s2 freq   +3735 delay  
    0
phc2sys[363008.921]: CLOCK_REALTIME phc offset        76 s2 freq   +3184 delay  
    0
phc2sys[363009.921]: CLOCK_REALTIME phc offset      -191 s2 freq   +2940 delay  
    0
​

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