Kantronics KAM 98, Руководство пользователя

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Among the problems that may arise in this situation are that: (1) UI packets can
be repeated much more than necessary, by the same or by different digipeating
stations with the callsigns RELAY, WIDE, or TRACE clogging up the airwaves,
and that (2) several stations may re-transmit the same packet at the same time, re-
sulting in a combined signal that cannot be copied by other stations.
Kantronics’ TNCs (v. 8.2) and the KAM’98 (v. 8.3) have a suite of UI digipeating
commands that can be used to deal with inefficiencies that can arise when a num-
ber of digipeaters are transmitting in the same area, at the same time, using the
same generic names.
Overview of UI Digipeating Commands
The following UI digipeating commands support advanced GPS/APRS
digipeating capabilities.
The UIDIGI command may be used to set up to four additional aliases/call signs
for “special” digipeating service. To-be-digipeated packets received containing
one of these aliases will be repeated (once) with the call sign (MYCALL) of the
digipeater substituted for the alias in the digipeated frame. See the example
shown below and the command description for more detail.
UIFLOOD and UITRACE are a bit more exotic. Each provides for multi-hop
digipeating with just one digipeater address per packet, thereby keeping the trans-
mission time short. For example, to digipeat through three TNCs supporting the
UIFLOOD command, the reporting station might set a GPS position path as fol-
lows:
LTP 1 GPS via wide3-3.
A digipeater TNC supporting “wide” set by the UNIFLOOD command and hear-
ing the reporting station’s transmission would then digi the UI location packet
(assuming it had not done so already, within a preset time), using an address of
wide3-2. In turn each similar digipeater down line would digi the reporting sta-
tion’s UI packet and reduce (decrement) the ssid of the digipeater address again.
A TNC using UIFLOOD has the option of inserting MYCALL, creating two
rather than one digipeater addresses in each transmitted digi packet.
With UITRACE, each time a packet is digipeated, each TNC adds its MYCALL,
thus creating a “trace” or return path. In effect, the size of the packet grows by
Packet Modes of Operation GPS NMEA Interfacing Capability
User’s Guide 190 KAM’98 v 8.3