There are several reasons why YAAC may not start on a particular computer
The types of maps supported by YAAC are both vector and raster maps.
The OpenStreetMap data is vector-based, and can be zoomed to any arbitrary level and seen just as clearly, because it will be redrawn from scratch at the current zoom level to look good. Also, YAAC is smart enough to leave out extremely fine details when zoomed out to cover a large area, and reintroduce those fine details as the map is zoomed in enough to distinguish those elements.
The U.S. Geological Survey's Shuttle Radar Topographic Mission elevation data is raster data; as you zoom in, it will start to appear "chunky" as the size of a single piece of map data becomes a noticeable part of the screen area. Similarly, other raster maps like the US National Weather Service radar map and arbitrary raster overlays will also become "chunky" when zoomed in closely.
YAAC has been deliberately designed not to depend on any Internet-based map server as a primary map data source. It is intended to be usable in situations where the Internet is not accessible (such as emergency conditions), and therefore only uses mapping capabilities that are self-contained within the computer running YAAC. Even the weather radar map capability stores the current weather map on the local computer for rendering (and will simply not display the weather map if it cannot be downloaded).
You may not have installed any OpenStreetMap or SRTM data on your computer. Download and import OpenStreetMap data, or copy pre-processed tiles from the YAAC author's website, or download SRTM terrain data from the U.S. Geological Survey.
You may have misconfigured the directory for the map tiles to point to a place where no map tiles exist.
You may not have map tiles for the area of the Earth currently being viewed in the YAAC map window (for example, there are no streets in the middle of the ocean).
YAAC may have added support for new OpenStreetMap features to the map data provided on the YAAC author's website, but you are still running an old version of YAAC that does not support those new features. You will need to upgrade your version of YAAC.
You may have turned off displaying geographical maps in the View->View Map Layers->Select Geographical Map Layers dialog.
OpenStreetMap data is enormous, since it provides street-level map data for the entire planet. As such, it takes time to analyze all that data and convert it into efficient map tiles.
However, YAAC's author has already converted the current OpenStreetMap data into YAAC tiles and has made it available for download from the File->OpenStreetMap->Download Precompiled Tiles menu choice, which is significantly faster than downloading the original compressed XML file and doesn't require any later processing because it has already been processed. So, unless you need OpenStreetMap data that is more recent than what the author has provided, or for some reason have to use an old version of YAAC that does not support current tile formats, we recommend you just download copies of his tiles.
The U.S. Geological Survey has "throttled" their website to protect against Denial Of Service attacks. As such, YAAC must download their SRTM files one at a time to prevent being blocked as an attacker.
To help in detecting emergency situations, when YAAC detects a station reporting emergency status, it will automatically pan the map to center on the reporting station and briefly display flashing red arrows pointing at the station. This will happen whenever a station is reporting emergency status in one of three ways:
This big yellow circle identifies your Aloha range, which is the maximum range your station can be digipeated over RF without saturating the RF channel. It is a function of the station density (number of transmitting APRS stations) in your local vicinity on the same channel, and the number of other objects and items reported in your area on that channel. The Aloha range is drawn as a dashed yellow circle if your station has not heard enough other stations and objects to estimate the Aloha limit, or a solid circle at the Aloha limit. The Aloha limit is an approximation, based on assumptions about typical transmission rates for different types of stations, and assuming equal omnidirectional propagation; it does not use terrain data or actual transmission rates to adjust the calculated range.
For further information, consult WB4APR's discussion on the subject at http://aprs.org/aloha.html.
One of the optional parts of the map display is the ambiguity circles. These plot the area a station could be in, given the possibly coarsened resolution of its position information. Although YAAC does not support reducing precision of its reported position, other APRS applications do support dropping the finest resolution digits of the position data. If you select the View->View Maps Layers...->Show Ambiguity option, these circles will be displayed as translucent ovals in the most common color of the icon image for the station.
The problem occurs when dead-reckoning is also enabled, and a rapidly moving mobile station shuts down without transmitting a final position with zero speed. The ambiguity circle is automatically enlarged to account for the last reported speed of motion, since YAAC will not know the actual current position of the mobile station until it beacons again. As such, the ambiguity circle for the station will continue to grow until the dead-reckoning timeout. Since airplane icons are in dark gray, and the car icon is outlined in black, both can cause gray circles to grow to cover the screen if YAAC loses reception of the beacons while the other stations are still moving rapidly.
There are several possibilities for this.
/dev/ttyXXXXfiles) before YAAC can open the devices. Typically, this requires that your account be a member of the Unix group that owns the serial port devices (usually called "dialout", "tty", or "uucp"), and also of the group that has write access to the system lock directory (/var/lock on most distros, usually owned by group "lock"). Have your system administrator grant your account memberships in those groups, and the problem should go away. The typical administrative command to do this is (must be done as root):
usermod -G tty,lock -a yourusername
Note you may have to log out and log back in again for the new group memberships to take effect.
Another possible cause of the problem is running YAAC on a non-Intel-CPU computer. The RXTX library used by YAAC to access serial port devices requires native machine code, and YAAC only ships with the RXTX code for a few operating systems on Intel CPUs. For other CPUs (such as the ARM processor in the Raspberry Pi computer), you will need to manually install your operating system distro's version of RXTX. On the Pi, the command would be
sudo apt-get install librxtx-java
For other operating systems, the installation command may be different, or you may have to download the RXTX source code, and compile and install RXTX yourself; consult your operating system's documentation.
There are several reasons why YAAC is receiving garbled data from your GPS receiver instead of proper NMEA-0183 sentences:
It can. To access the APRS-IS backbone, you need to open a port of type APRS-IS, get a valid passcode for your callsign (contact the YAAC author), and enable the port for transmission.
An I-Gate is a digipeating station that relays APRS packets between the APRS-IS backbone and local RF. As such, it needs both a transmit-enabled APRS-IS port to connect to the backbone, and an RF port (Serial_TNC or AGWPE) with a radio to be able to hear and transmit to other local RF stations. For more information, read this tutorial on YAAC I-gating.
There are four pre-requisites that have to be configured correctly before YAAC can function as a digipeater:
Also, is your radio correctly connected to the TNC or sound card (as appropriate)? YAAC can send frames to the TNC all it wants, but if the TNC can't push the radio's Push-To-Talk switch, it will never transmit.
You may not have specified your callsign for the beacon.
You may not have enabled beaconing (the Enabled checkbox on the Beacon tab of the expert-mode configuration dialog).
You may have specified GPS-based beaconing, and there isn't a GPS receiver port defined, or the GPS receiver is not currently producing a valid position fix.
You may not have enabled any TNC or APRS-IS ports for transmitting.
The age displayed below the callsign for each station on the map, and in the Station/Object view, is not the time since the station last transmitted a message; it is the time since YAAC last received a message from that station or about that object/item. As such, you will not see an age (or it will not reset to zero) if you are not receiving messages from that station. That includes your own station; if you are not hearing RF digipeaters echoing your station's packets, you will not see an age reset to zero (i.e., you just heard something). Note you will never hear your own station through your own APRS-IS connection.
Either you have changed filter options to stop showing those stations, or the station/object information has exceeded the configured maximum age before the station is discarded. See the Miscellaneous tab in the Edit Filter dialog or the General tab in the expert-mode Configuration dialog to change the expiration time.
Click the Locate menu and select "Station or Object". You can enter the callsign, or select it from the drop-down in the displayed dialog box. Then click OK and the map will center on the location of the station (or former location for expired data) and flashing green arrows will highlight the station's most recent location (if it exists).
You can also double-click the mouse on the station or object's row in the Station Status or Object Status tables (as appropriate).
The station may not have transmitted position information yet. Until it does, the station will be plotted on the map with a "vicinity location", randomly near the first digipeater to hear it. If that digipeater has not provided position information either, the station will be displayed at latitude/longitude (0, 0) (off the western coast of central Africa) until such a time as position information for the station is received. The button will pan the map to (0, 0) so you can see the non-located stations.