Conclusions
Based on the results of the T&D tests, the SPOT personal satellite messenger is effective in transmitting messages, even under heavy tree canopies. Users can be confident that messages will be sent successfully, especially if they are able to send messages in any type of clearing. It is important to follow the manufacturer's recommendations and instructions to increase the likelihood of the message will be sent successfully. For example, it is important to leave the device in the open for 20 minutes when sending a check-in message. This allows the unit to send three redundant messages.
The tracking feature was affected both by tree canopy and the orientation of the device. Whenever possible, the SPOT device should be oriented so the face is pointing to the sky. This places the antenna in the best orientation.
The SPOT has some significant limitations that should preclude the device from being a primary check-in/check-out device. These include:
- The device provides one-way communication only. No one can contact the SPOT user. This limitation is the main reason why the cost of the unit and the satellite service can be so low.
- The SPOT device provides no feedback that would allow users to know that their messages were sent and received successfully.
- The Web site is not designed for large numbers of devices or for corporate users. Security and privacy concerns (contact information) are key problems. SPOT is developing a solution for corporate users that should address these concerns.
- The device can be confusing to use. For instance, the user has to push and hold the OK button for 5 seconds to enable the tracking feature. This command won't work if the unit is still trying to send another message. In such a case, the user must turn the unit off and back on to cancel the message.
Overall, the SPOT device worked fairly well. However, field units should consider the device as a backup or enhancement for normal communications. The primary limitation is its inability to provide two-way communication.
