Hello everyone
We have been wondering about rx_time tags after drop. In [1] it is stated that "Then, if a dropped
packet or overflow are detected, it sends a new rx_time tag."
The tag debugger output is shown below.
Initially we thought that in the tag the time and the offset are bound together. Instead seems that this is true only for the first tag. Meaning, the offset is always bound to the initial rx_time, as one can see from the example printout. Both the offset and the time increase (sampling rate is 10e6).
Actually, now that I look at them the rx_time values are messed up, they are not even monotonically increasing (the timestamp in the second tag is "newer" than in the third). So what does the rx_time in the tag after drop represent?
In any case, isn't this a bit counter intuitive? I know we fell for it at first. There might be more places in the code that mishandle the rx_time tags after drops. I understand that drops should be avoided, but still I think it is crucial that they are correctly handled.
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Tag Debug:
Input Stream: 00
Offset: 0 Source: gr uhd usrp source1 Key: rx_time Value:
{1480518095 0.75052}
Offset: 0 Source: gr uhd usrp source1 Key: rx_rate Value: 1e+07
Offset: 0 Source: gr uhd usrp source1 Key: rx_freq Value: 1.56e+08
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D
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Tag Debug:
Input Stream: 00
Offset: 17461752 Source: gr uhd usrp source1 Key: rx_time Value:
{1480518097 0.497203}
Offset: 17461752 Source: gr uhd usrp source1 Key: rx_rate Value:
1e+07
Offset: 17461752 Source: gr uhd usrp source1 Key: rx_freq Value:
1.56e+08
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D
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Tag Debug:
Input Stream: 00
Offset: 17471916 Source: gr uhd usrp source1 Key: rx_time Value:
{1480518097 0.496695}
Offset: 17471916 Source: gr uhd usrp source1 Key: rx_rate Value:
1e+07
Offset: 17471916 Source: gr uhd usrp source1 Key: rx_freq Value:
1.56e+08
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D
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Tag Debug:
Input Stream: 00
Offset: 17476998 Source: gr uhd usrp source1 Key: rx_time Value:
{1480518097 0.498219}
Offset: 17476998 Source: gr uhd usrp source1 Key: rx_rate Value:
1e+07
Offset: 17476998 Source: gr uhd usrp source1 Key: rx_freq Value:
1.56e+08
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With regards
Meelis