[CQ-Contest] Alice and Bob QSO Party

Tom Horton k5iid at sbcglobal.net
Sat Jun 28 13:13:00 EDT 2014

 It would have been better if it had been Alice and Paul or Pete, etc.

Nice to finally meet you at Ham Com!
 Tom K5IID

There is no joy in Mudville!

K5IID Tom Horton  Hillsboro, TX
E sorter for ARRL W5 bureau
Same call for 57 years!

On Saturday, June 28, 2014 10:09 AM, Ward Silver <hwardsil at gmail.com> wrote:

Just to stimulate discussion, here's an idea for the "Alice and Bob 
(ALBO) QSO Party" :-)

For the exchange, each station sends a fixed-length hexadecimal 
character group (characters 0-9 and A-F) that is the digital product of 
the *other* station's call sign and a random number generated by the 
sending station's logging software.

If the station receiving the character group has the correct call sign 
of the sending station, reversing the multiplication recovers the random 
number which is then matched in log checking for full credit.  If either 
station has the other station's call sign wrong, the random number won't 
be correct and no credit for the contact is given.

Since the running station has to give the search-and-pounce station's 
call sign to initiate the QSO, there is a built-in check for the 
search-and-pounce station to verify that their call has been received 

Runner:   CQ ALBO N0AX
Searcher: W1AW
[Runner software generates random number 12345 and computes W1AW x 12345 
= 0A246E or something, just made that up]
Runner:   W1AW 0A246E
[Searcher divides 0A246E by W1AW and logs 12345]

If the Runner has the Searcher's call sign wrong (WA1W, for example) 
then the random number won't be recovered correctly, but the Searcher 
will hear the incorrect call and can correct it just like we do in 
current contests.

Now the fun begins...the Searcher generates their own random number 
54321, calculates N0AX x 54321 = 47BC28 and can either send:

Searcher: R 47BC28
[Runner *assumes* the Searcher knows the call sign N0AX and divides 
47BC28 by N0AX to get and log 54321]
Searcher: R N0AX 47BC28
[Runner now has a check that the Searcher has copied their call sign 

If the search-and-pounce station does not include the running station's 
call in their response, the running station has to trust that the 
search-and-pounce station has their correct call.  This is faster and 
leads to a higher rate but is less reliable because if the 
search-and-pounce station does not have the correct call for the running 
station, the random number recovered by the running station won't be 
correct and the QSO won't count. Thus, there is a built-in, but dynamic, 
brake on a running station's assuming their call sign is known and not 
sending it "in the clear."  Is sending all calls every time the optimum 
strategy to maximize score?  Or maybe every other QSO?  Every third QSO?

Search-and-pouncing stations can not guess the random number by 
listening to other contacts, either.  As always, both call signs have to 
match in the log-checking database and the number representing the 
product has to be copied correctly.

Since all of the computations are done by the logging software, the 
human operators are just sending and receiving character groups, not 
unlike CQ WPX.  Additional information for multipliers can be added in 
the clear, as well.  Ready for contesting 2.0?

Have fun on Field Day - show our new hams how it's done!

73, Ward N0AX

PS - The reference to Alice and Bob relates to those two names being 
typically used to identify the two parties in an exchange of encrypted 
information. (http://en.wikipedia.org/wiki/Alice_and_Bob)

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