[OZAPRS] Foxtrack interoperability

[Owen Duffy]

Hello All,

Many people are aware that Foxtrak trackers are not decoded reliably by
certain Argent Data devices (eg current versions of Open Tracker 3, Open
Tracker USB on my tests).

It seems that the underlying issue is that the DSP based decoder used in
current versions of those products is not tolerant of the modulation
generated by the Foxtrak (whereas all of the TNCs I have tested decoded
Foxtrak just fine).

Exploring the issue more widely, the same problem exists with not only
the default firmware by DK7IN, but also original TinyTrak v1 firmware
and aprstraker v0.11.

Before you dismiss this as an issue for Foxtrak hardware...

I have conducted comparative tests of a genuine TinyTrack3+ and Foxtrak
both fitted with TT3+ v1.42 firmware, and can report that they are both
decoded well, and equally well by VK2RHR-1 which is an Open Tracker 3.

There are two messages from all of this:

  * if you operate a digi, select equipment that reliably decodes most
    of the common trackers etc, and equipment that uses DSP decoding
    requires more careful evaluation than that which uses traditional
    modem chips;
  * if you operate a tracker and want it to be decoded by most digis and
    iGates, choose equipment compatible with existing infrastructure
    (which includes a lot of Argent Data devices).

A possible solution for owners of Foxtraks and early TinyTrackers might
be to upgrade the chip or whole device to TT3+ v1.42 (which is better in
a whole lot of respects).

Note that I have not tested TT3+ with DSP based decoders other than
Argent, so I cannot comment on compatibility for instance with Microsat
(which are used in Australia). Perhaps hams using those systems can
share their experience.

In researching the topic, it became clear that the manufacturers of DSP
based decoders appear to not perform interoperability testing with other
brand products... the buyer must do it!

73
Owen
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