RE: rx_time

[Daniel R. Marlow]

-----Original Message-----
From: Discuss-gnuradio <discuss-gnuradio-bounces+marlow=princeton.edu@gnu.org> 
On Behalf Of Marcus D. Leech
Sent: Saturday, July 23, 2022 9:24 PM
To: discuss-gnuradio@gnu.org
Subject: Re: rx_time

On 2022-07-23 16:53, Daniel R. Marlow wrote:
> Hello,
>
>     I am having trouble understanding the 'rx_time' field in the gnuradio 
> metadata.   In particular, if I use the following code to unpack the metadata:
>
> self.handle = open(filename, "rb")
> header_str = self.handle.read(parse_file_metadata.HEADER_LENGTH)
> header = pmt.deserialize_str(header_str) info = 
> parse_file_metadata.parse_header(header, False)
> print("info[rx_time]={0}".format(info['rx_time']))
>
> The print statement gives:
> info[rx_time]=6634431378.28
>
> I was expecting a time in seconds past the epoch (something in the 
> neighborhood of 1658609226).
>
> Any information on what I am doing wrong would be most appreciated.
>
> Details: B210 with GPS module, Gnuradio 3.7.9, Ubuntu 16.04
>
> Sincerely,
> Dan Marlow
>
>
>
>
>     I am using a B210 board with a GPS module.
>
How are you setting the time on the USRP B210?

I have a manually-inserted code snipped, included below that I've used in the 
past to set the timestamp clock from the GPS time on a B210:

def lock_to_gps(uhd_src):
     while(not uhd_src.get_mboard_sensor("gps_locked").to_bool()):
         time.sleep(0.1)
     time.sleep(0.2)
     while(not uhd_src.get_mboard_sensor("ref_locked").to_bool()):
         time.sleep(0.1)
     time.sleep(0.2)

     # Spin, waiting for PPS transition
     t = uhd_src.get_time_last_pps()
     while (t == uhd_src.get_time_last_pps()):
         time.sleep(0.05)
     #Set the time from the GPS time
     gps_time = uhd_src.get_mboard_sensor("gps_time").to_int()
     uhd_src.set_time_next_pps(uhd.time_spec(gps_time+1))
     #This sleep is recomended to stabilize the clocks
     time.sleep(1.5)

Hi Marcus,

    Thanks.   I tried that, but got the same result.   I think that my problem 
may be more basic.    Specifically, I think that I don't know how to interpret 
the info['rx_time'] object.   It seems like it is a float.   If so, then I 
don't know what the units are.

Cheers
Dan