[FoxHunt] IARU controller question

[Kuon & Dale Hunt]

Charles wrote:

>
>It wasn't until I hunted using an AM transmitter to track an FM fox (slope
>detection) that I realized the problem ,,,
>
>With an AM receiver I could only track the fox when a tone was being sent.
>Which meant that only for a small fraction of the 1-minute cycle was I able
>to actually track the fox...


    As those of you know who have attended ARDF events in other
    Regions, keyed-carrier AM tone modulation is the standard.
    (Though I did encounter the continuous carrier FM in Japan.)

    This provides an experience similar to hunting 80m signals -
    you can only take a bearing during the tone portion of the cycle.

    One thing I noticed when hunting a keyed-carrier AM signal in
    Victoria was that it would not open the squelch on my 2m HT,
    regardless of how strong the signal was.  (I've had the same
    experience listening for ELT beacons using a 2m rig with AM
    receiver in the Aircraft band:  apparently the squelch was
    still designed for FM.)  In both cases I had to hunt with the
    squelch open.  This poses a bit of a dilema when we are trying
    to gain experinence at international hunts while encouraging
    newcomers to try the sport.

    Actually, one advantage of the keyed carrier transmission is
    that you can tell which transmitter you are listening to even
    when "whoopee" (tone "S"-meter) receiver mode.

    At this point I think we will all just use whatever transmitters
    we have available, but it is a point to consider as we plan for
    new ones.



>
>When Region 2 writes its ARDF rules we should consider whether to require
>that FM transmitters turn off their carriers between "MOx" transmissions.
>This would level the playing field between those using AM receivers and
>those with receivers equipped with S-meters.
>
>In the meantime I've reprogrammed my Montreal controllers to send the
>callsign identifier first, and then they transmit standard code characters
>and spacing until the end of their transmission.


    Actually the ID first is the proper method of ID'ing in Canada,
    where the rules state each station must ID at the beginning of
    an exchange of transmissions and at least every 30 minutes
    thereafter.  Technically it would be legal under US rules as long
    as you let it ID before turning it off.

    Meanwhile, a further technicality:  the US rules require any ID
    sent automatically in Morse Code to be no faster than 20 WPM.

    Playing the ID at a different speed/tone freq is probably a good
    idea when we have visitors from other Regions, since I've never
    yet encountered a transmitter in Region 1 that had an ID on it.
    This will clue in the hunter that this is NOT part of the
    standard MOE/I/S sequence.  (Especially Charles, or they might
    think every transmitter is TX #2!)


         - Dale WB6BYU