TeleGPS has a two pin JST PH series connector to connect up a single-cell Lithium Polymer cell (3.7V nominal). You can purchase matching batteries from the Altus Metrum store, or other vendors, or you can make your own. Pin 1 of the connector is positive, pin 2 is negative. Spark Fun sells a cable with the connector attached, which they call a JST Jumper 2 Wire Assembly

TeleGPS logs GPS data at a user-configurable rate. Data are logged to a 2MB on-board flash memory part, which can be partitioned into several equal-sized blocks, one for each flight. 64kB of this storage are reserved to hold configuration data, leaving 1984kB for flight data.

The on-board flash is partitioned into separate flight logs, each of a fixed maximum size. Increase the maximum size of each log and you reduce the number of flights that can be stored. Decrease the size and you can store more flights.

To compute the amount of space needed for a single log, you can divide the expected time (in seconds) by the sample period (by default, 1 second per sample) and then multiply the result by 32 bytes per sample. For instance, a sample period of 1 second and a flight lasting one hour will take 32 * 3600 = 115200 bytes. TeleGPS does try to reduce log space used by not recording position information when it isn’t moving, so actual space consumed may be less than this.

The default size allows for four flights of 496kB each, which provides over four hours of logging at 1 sample per second.

TeleGPS will not overwrite existing flight data, so be sure to download flight data and erase it from the onboard flash before it fills up. TeleGPS will still report telemetry even if memory is full, so the only thing you will lose is the on-board data log.

The battery connectors are a standard 2-pin JST connector and match batteries sold by Spark Fun. These batteries are single-cell Lithium Polymer batteries that nominally provide 3.7 volts. Other vendors sell similar batteries for RC aircraft using mating connectors, however the polarity for those is generally reversed from the batteries used by Altus Metrum products. In particular, the Tenergy batteries supplied for use in Featherweight flight computers are not compatible with Altus Metrum flight computers or battery chargers.

TeleGPS uses an integrate GPS patch antenna and won’t receive GPS signals if installed inside a metal or carbon fiber compartment. Test GPS reception and telemetry transmission with the system installed and all other electronics powered up to verify signal reception and make sure there isn’t any interference from other systems.

This is the window brought up when you start the application. If you have a TeleDongle device connected to the computer, it will automatically be selected for telemetry monitoring

All telemetry data received are automatically recorded in suitable log files. The name of the files includes the current date and TeleGPS serial and flight numbers.

The radio frequency being monitored by the TeleDongle device is displayed at the top of the window. You can configure the frequency by clicking on the frequency box and selecting the desired frequency. The TeleGPS application remembers the last frequency selected for each TeleDongle and selects that automatically the next time you use that device.

Below the TeleDongle frequency selector, the window contains a few significant pieces of information about the altimeter providing the telemetry data stream:

Finally, the largest portion of the window contains a set of tabs, each of which contain some information about the TeleGPS board. The final table tab displays many of the raw telemetry values in one place in a spreadsheet-like format.

3.1.1. Map

The Map tab shows the TeleGPS track over time on top of map data making it easy to locate the device.

Figure 3.1. TeleGPS Map View

The map’s default scale is approximately 3m (10ft) per pixel. The map can be dragged using the left mouse button. The map will attempt to keep the rocket roughly centered while data is being received.

You can adjust the style of map and the zoom level with buttons on the right side of the map window. You can draw a line on the map by moving the mouse over the map with a button other than the left one pressed, or by pressing the left button while also holding down the shift key. The length of the line in real-world units will be shown at the start of the line.

Images are fetched automatically via the Google Maps Static API, and cached on disk for reuse. If map images cannot be downloaded, the rocket’s path will be traced on a dark gray background instead.

You can pre-load images for your favorite launch sites before you leave home; check out Section 3.5, “Load Maps”.

3.1.2. Location

The Location tab shows the raw GPS data received from TeleGPS.

Figure 3.2. TeleGPS Location View

3.1.3. Status

The Status tab shows data relative to the location of TeleGPS when the application first received telemetry from it.

Figure 3.3. TeleGPS Status View

3.1.4. Table

The Table tab shows detailed information about the GPS receiver

Figure 3.4. TeleGPS Information Table

TeleGPS has three or four menus at the top of the window:

The Graph tab shows a plot of the the GPS data collected. The X axis is time in seconds; there are a variety of Y axes available for different kinds of data. This window also allows you to see some statistics computed from the data, and an overall map of the entire data record.

3.3.1. Data Graph

Figure 3.5. TeleGPS Graph

3.3.2. Graph Configuration

Figure 3.6. TeleGPS Graph Configuration

This selects which graph elements to show, and, at the bottom, lets you switch between metric and imperial units

3.3.3. Statistics

Figure 3.7. TeleGPS Statistics

Shows overall data computed from the flight.

3.3.4. Map

Figure 3.8. TeleGPS Map

Shows a map of the area overlaid with the GPS track. As with the telemetry monitoring window, you can select the style of map and zoom level using buttons along the side; you can scroll the map by dragging within the map pressing the left button and you can draw a line to measure distances using either the left button with the shift key, or any other button.

This tool takes the raw data files and makes them available for external analysis. When you select this button, you are prompted to select a data file, which can be either a .eeprom or .telem. The .eeprom files contain higher resolution and more continuous data, while .telem files contain receiver signal strength information. Next, a second dialog appears which is used to select where to write the resulting file. It has a selector to choose between CSV and KML file formats.

Figure 3.9. Load Maps Window

Before heading out to a new launch site, you can use this to load satellite images in case you don’t have internet connectivity at the site.

There’s a drop-down menu of launch sites we know about; if your favorites aren’t there, please let us know the lat/lon and name of the site. The contents of this list are actually downloaded from our server at run-time, so as new sites are sent in, they’ll get automatically added to this list. If the launch site isn’t in the list, you can manually enter the lat/lon values

There are four different kinds of maps you can view; you can select which to download by selecting as many as you like from the available types:

You can specify the range of zoom levels to download; smaller numbers show more area with less resolution. The default level, 0, shows about 3m/pixel. One zoom level change doubles or halves that number. Larger zoom levels show more detail, smaller zoom levels less.

The Map Radius value sets how large an area around the center point to download. Select a value large enough to cover any plausible flight from that site. Be aware that loading a large area with a high maximum zoom level can attempt to download a lot of data. Loading hybrid maps with a 10km radius at a minimum zoom of -2 and a maximum zoom of 2 consumes about 120MB of space. Terrain and road maps consume about 1/10 as much space as satellite or hybrid maps.

Clicking the Load Map button will fetch images from Google Maps; note that Google limits how many images you can fetch at once, so if you load more than one launch site, you may get some gray areas in the map which indicate that Google is tired of sending data to you. Try again later.

This closes the current window, leaving any other windows open and the application running.

This closes all TeleGPS windows and terminates the application.

Selecting this item brings up a dialog box listing all of the connected TeleDongle devices. When you choose one of these, AltosUI will display telemetry data as received by the selected TeleDongle device.

Figure 3.11. Device Selection Dialog

Disconnects the currently connected TeleDongle or TeleBT

Figure 3.12. Radio Scanning Dialog

Scans the configured set of frequencies looking for telemetry signals. A list of all of the discovered signals is show; selecting one of those and clicking on Monitor will select that frequency in the associated TeleGPS application window.

TeleGPS records data to its internal flash memory. On-board data is recorded at the same rate as telemetry but is not subject to radio drop-outs. As such, it generally provides a more complete and precise record. The Download Data menu entry allows you to read the flash memory and write it to disk.

Select the Download Data menu entry to bring up a list of connected TeleGPS devices. After the device has been selected, a dialog showing the data stored in the device will be shown allowing you to select which entries to download and which to delete. You must erase flights in order for the space they consume to be reused by another track. This prevents accidentally losing data if you neglect to download data before starting TeleGPS again. Note that if there is no more space available in the device, then no data will be recorded.

The file name for each data log is computed automatically from the recorded date, altimeter serial number and flight number information.

Figure 3.13. TeleGPS Configuration Dialog

Select this button and then select any connected TeleGPS device from the list provided.

The first few lines of the dialog provide information about the connected device, including the product name, software version and hardware serial number. Below that are the individual configuration entries.

At the bottom of the dialog, there are four buttons:

The rest of the dialog contains the parameters to be configured.

This reprograms TeleGPS devices with new firmware. Please read the directions for flashing devices in Appendix D, Updating Device Firmware.