# Configure Transmit

This tab of the Configure dialog specifies the general parameters controlling message transmission.

The options that can be changed here are:

- The maximum age of messages that will be seen in the GUI. Anything older than the specified time interval (relative to current time) will be hidden on the map or grayed out in the sniffer window.
- The callsign or alias used as the destination for local beacon transmissions (when sending all locally originated packets except for Mic-E encoding position messages). Referred to in the APRS protocol documentation as the "tocall", different values are assigned to different makes and models of APRS hardware and software, so other stations on the APRS network can identify what type of station is sending them packets. Although you can enter any up-to-6-character string here (non-standard values here identify an alternate network [not necessarily an APRS network], or "altnet"), YAAC supports three standard values:
  - APJYC1, the specific value identifying the YAAC software. This is the YAAC software default.
  - APRS, the generic value saying the sending station is APRS, but no further information about the station type or capabilities.
  - BEACON, the older connected-mode packet destination used for unconnected multicasting of the station's beacon packet.
  The full list of assigned "tocalls" is available at http://aprs.org/aprs11/tocalls.txt.
- The initial (fast) beaconing rate in seconds between beacons.
- The rate at which beaconing is slowed down when there are no data changes. Either doubling or tripling the transmission interval is supported.
- The slowest rate (maximum interval between transmissions) that local beacons can be sent at, in seconds between transmissions.
- The maximum number of times an APRS text message will be retransmitted if it is not acknowledged by the addressed remote station.
- Whether I-Gating from RF to the Internet (RX-IGate) and/or I-Gating from the Internet to RF (TX-IGate) is allowed (should the configuration have both RF and APRS-IS ports open and enabled for transmission), and the maximum number of digipeater hops acceptable for a local station to be I-gated (also configures the digipeat alias for TX-IGated messages).
- Whether or not Smart Beaconing should be used when the station is moving (according to received GPS data).
- The slowest and fastest rates of travel of the mobile station that will be used to interpolate the transmission rate for beacons.
- The minimum turn angle and scaling factor (turn slope) for how sensitive YAAC should be to course turning regarding speeding up beacon transmission.
- Whether or not to respond to QRU requests heard by this station. Note that this station will not respond unless:
  1. this station has QRU objects for the specified category (or for any category if the requesting station is sending an INFO request for a list of supported groups).
  2. the requesting station is in range (see the next Transmit control).
- What maximum distance the requesting station can be from this station where this station will still send QRU responses. This distance will be in the units specified on the Preferences tab of the configuration dialog.
- The port number the internal mini-webserver will listen on for browser requests. External browsers can view some of the YAAC views by using the URL http://ipaddressofYAACsystem:portnumber. Note that port number 0 turns off the mini-webserver, and ports between 1 and 1023 may not work on Linux or Unix platforms, as they are reserved for privileged network services.
- The interval in seconds between automatic refreshs of the pages viewed on YAAC's mini-webserver. This keeps the views on the other browsers up-to-date as new real-time data is received by YAAC.