[hpsdr] windows 10 is dropping udp packages

[Scott Traurig]

Johan,

Many, but not all, Microsoft Windows installations will, for some reason,
deliver out of order but not missing UDP packets to the application layer.
Left uncorrected, this will cause sequence error indications in both
PowerSDR mRX and Thetis.

This problem has been worked around in PowerSDR by means of the "PRO
latency" setting. This is the number of UDP packets that will be buffered
for reordering. "0" will turn off this feature, "4" will buffer 4 UDP
packets. There have been no observations of packets arriving out of order
by more than 4 packets, and rarely more than just a single packet out of
place (swapped packets). The larger the reordering value the more latency
one has on receive. However, under typical conditions it's only about 3.5mS
per packet.

Also in PowerSDR mRX is an "OOOPS" counter, which is a rather unfortunate
name for what is essentially a dropped packet counter. Any packet that is
effectively lost because it is further out of order than the PRO feature
can handle, or just out and out gone, will be counted by this counter. You
should not see more than a handful of counts per hour. A non-zero number is
normal, of course, because as you know UDP is an inherently lossy protocol.

Unfortunately, neither of these features have been ported to Thetis yet.

I'd recommend running P1 and PowerSDR mRX to ensure that you do not have a
major problem with your Windows and network installation, as the necessary
diagnostics are not in Thetis yet.

73,

Scott/w-u-2-o
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