Hello all,
I’ve recently started working with the EVK-1000 kit doing some simple point-to-point, single Anchor, single Tag, range testing to familiarize with the system. I’m testing with the Tag standalone running the DecaRanging ARM application and powered by a USB battery pack and the Anchor powered by PC USB and controlled by the DecaRanging PC application. I’ve been utilizing the “Channel Respose Log” functionality to have a record of the distances as I conduct testing. That aspect has worked well, but I’m trying to better understand the Rx and Tx timestamps (reference DecaRanging PC User’s Guide sections 4.2 and 4.3).
I see in the log file various Tx and Rx timestamps. I understand the nature of the communication protocol with the Poll/Response/Final framework, but it is the actual timestamps here expressed in scientific notation that I don’t understand. What is this time in reference to? What unit is the time in?
When I see a series of Rx/Tx/Rx such as:
21 74 Rx time = 1.608443040713579e+001 EF4B0FA59F
90 Tx time = 1.623443065844414e+001
29 74 Rx time = 1.643443053953513e+001 F48011C6AB
It seems to make sense because each timestamp is a higher number than the previous one. However, when I see a series such as:
21 76 Rx time = 1.708640614285983e+001 FE332DFD42
92 Tx time = 2.900536998259716e-002
29 76 Rx time = 2.290052341715495e-001 0368301A73
I don’t really know what to make of it.
Please note that I’m using Notepad++ to open the log file and then using the Find function with Regex to search for the string: ^((.21 … RX time =.)|(.29 … RX time =.)|(.TX time =.)|(.Anchor.))$ effectively condensing the log file into timestamps and distance calculations.
Any help would be greatly appreciated.
Thanks!
Nick
Rx time is the time of reception of a frame - decimal is the DW1000 time converted to seconds, hex is the DW1000 time (40 bit number)
Rx time(un) is the raw time stamp before any DW1000 time adjustments after first path calculation in LDE
RXDATA: these are the received bytes
txdly and rxdly are the TX and RX antenna delays as programmed
Accum Len 1016 - these are the real and imaginary parts of the accumulator CIR for the received frame
Tx time is the time of the frame transmission (has TX antenna delay added)
RX OK - this signifies good reception
HLP - this is first path index in the accumulator
PSC - number of accumulated preamble symbols
NTH - noise threshold
T - temperature and voltage - read from DW1000 on frame reception
RSL - received signal level (dBm) - calculated as given by the formula in User Manual
FSL - first path signal level (dBm) - calculated as given by the formula in User Manual
/Leo
Thank you for the reply. So if a timestamp is in seconds, what is the reference point? Is it time since the test started or is there just some running timer?
What’s going on in the example I posted where you have a poll at 1.70e+1, response at 2.90e-2, and final at 2.29e-1? The timestamps don’t seem to line up correctly.
21 76 Rx time = 1.708640614285983e+001 FE332DFD42
92 Tx time = 2.900536998259716e-002
29 76 Rx time = 2.290052341715495e-001 0368301A73
Please read the DW1000 UM. And DecaRanging Application user manual where the log format is described. 
If you still can’t figure it out let me know.
Z
Hi Nick,
According to the user’s manual, page 73:
The timestamp register is 40-bit, counting at 128499.2 MHz (which is approximately 64Hz or a 15ps period).
Then after (2^40)/(128499.2*10^6) = 17 . 207 401 025 641 seconds it will wrap around.
Best regards,
Fellipe Saldanha Garcia
Hi,
Just to correct the previous message: (which is approximately 64GHz or a 15ps period).
Best regards,
Fellipe Saldanha Garcia
Felipe,
Thank you for the response. I was missing the connection with the System Time Counter. It makes sense now.
Regards,
Nick
