[drats_users] Field use & questions

[Arnold Harding]

Dan,
Thanks for the reply.
>
> That's likely true, yes.  The ping (or chat) packet is very small 
> and
> can get through easier than a larger data packet that's more likely 
> to
> take a hit.  You can mitigate this by reducing your packet size (and
> optionally increasing the window size).  This won't eliminate the 
> need
> for retransmissions, but it does mean that a smaller amount of data
> will have to be resent for a given number of bit errors.
>
I don't understand how making the window size larger will help 
communications.  Obviously I'll see more on the larger screen, but... 
OK, just kidding.  I know these parameters are in Transfers and 
Tuning.  Is there something already written up on their usage?

>> a) Can there be some sort of larger ping which can test the quality
>> of a path?  The ping would need to send and return a large block
>> each way, then give some sort of report.
>
> Yes, I can add something to allow you to set how much padding goes
> with the ping which will help (thus letting you send a bigger ping
> packet to see if it gets through).  I can also do a more coordinated
> multi-packet ping where it starts small and ramps up to some larger
> ones.
This would be a help.  Could it somehow be a bounce, where both 
directions get tested?  ACKs are short, and don't tell much. Then it 
only takes one operator to do the test while the "far end" can do 
other tasks until asked to change frequency, or see the file.
>


> I've not had a single instance where the resume of a normal file has
> not gone through as expected.  So, I assume you're hitting the above
> scenario.
>
OK, operator error.  At least we tried...

>> Having a file transfer just appear to stop and have D-RATS just
>> sitting there is quite frustrating.  "I didn't interrupt it, so 
>> what
>> happened?" is the only thing I know.  Having D-RATS get to 96% of a
>> file transfer, then stop without even an "interrupted" message just
>> leaves us wondering.
>> c)  What happened???  If it does say "Transfer Interrupted", by 
>> what?
>
> "Transfer Interrupted" means that it gave up trying to get a packet 
> to
> the remote side.  It's completely an RF thing in that case, where 
> it's
> not able to get data through to the other end.  There's not much 
> else
> it can do in that case, of course.

But what about the couple of cases where it just sat there...  no 
"Transfer Interrupted" or anything?  Sorry I can't supply much in the 
way of details, but I'd hit send, then walk off to do other chores, 
come back to see what's going on.  How long, or how many sessions of 
log might get kept?  Since I was on battery power I turned off the 
computer a couple of times when it clearly wouldn't be needed.

>
>> Plain old Packet would have been more reliable, but more equipment,
>> radios, and adjustments would have been needed.
>
> Well, unfortunately they have a 20+ year head start on me, what can 
> I
> say? :)
We did packet 2 years ago and found that the amount of equipment 
required and the set up time was more than we wanted to do.  Even 
knowing that D-RATS is changing as the learning goes on, we were very 
willing to put it to use.  At first we considered having a fall-back 
of packet, but D-RATS made us all confident enough that we didn't 
bother.


> Do you have any plans to recreate some of the scenarios not under 
> the
> gun to perform for the event?  That may help us get a better handle 
> on
> what sorts of things to work on.
>
Probably not from these locations.  Just getting to the locations 
takes a minimum of an hour (for me, 2 1/2).  For example, load these 
coordinates into Google Earth:
37 23.544N 121 29.406W
This is where my car was located.  The only reachable voice repeater 
was 8 miles away to the east, and I put this temporary voice repeater 
there about 2 hours before I need to be at my stop, then at the end of 
the day, pull the voice repeater down.  Near the FM voice repeater is 
the other station I transferred files via simplex.
For some of our initial testing, I was sending and receiving through a 
D-STAR repeater 60 miles from my house without any problems on 5 
watts.  Some of the Hams testing D-RATS within 10 miles of the 
repeater had a much more difficult time getting data through.  Again, 
knowing how the tuning parameters adjust stuff will be a help.


>> D-Star with D-RATS got what we needed accomplished, even with the
>> problems.
>
> Thanks a lot for the write-up!  Real-life usage stories are *always*
> welcome!
We are planning on doing a much nicer and larger write-up.  I know 
I've had D-Star for almost 3 years, and it keeps getting better.

73, Arnold
KQ6DI
>
> -- 
> Dan Smith
> dsmith#danplanet.com, s/#/@/
> www.danplanet.com
> KK7DS
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