My Day with the GSC-100

June 7, 1998 -- This past weekend (7 June) I had a booth at the Manassas Hamfest. I asked Orbcomm to loan me a Magellan GSC-100 hand-held satellite terminal and GPS for our display, and they let me use a beta test terminal for a day. Based on that use, here are my admittedly biased impressions. (The unit had a built in GPS receiver, but since I was not concerned about that capability this article only looks at the satcom features.)

When someone is carrying one of the terminals, the main question is "when is the next satellite pass?" Certainly, you don't want to have to stand there all day waiting for a satellite pass. The Magellan unit has a neat display that shows your position in relation to the next pass. You are in the middle of two concentric circles with a North arrow on the side. The inner circle represents a 45-degree elevation and the outer circle is the horizon or zero degrees. The display tells how long till the next pass, provides a track of the pass, and a hollow square on the track shows where the satellite is now. The box turns dark when you are communicating with the satellite. There is also a signal strength bar on the side so you can see how well the satellite's signal is being received. You can also scroll down and see, in text format, when the next passes will occur. The process is intuitive to use, and no one had trouble with it.

Each message can have a 260-character subject line and 2000-character message body. At our prices, no one will want to exceed those limits. A good function key was a two stoke set that put your location and the time into the message.

Standard messaging with Orbcomm has the satellite act as a bridge between the satellite terminal and the earth station. Only if you specifically request the service will a message be sent as a store-and-forward message or Datagram (in which the message is stored in the satellite's memory until it sees an earth station). You must specify if the message is a Datagram; otherwise it remains in the standard queue until the terminal contacts a satellite that has an earth station in sight. An interesting feature was the GSC-100's ability to move a message from the Datagram queue to the standard message queue automatically if an earth station is connected. That's a great idea since it relieves the subscriber of managing queues. It doesn't work the other way, though, because of the higher expense of the Datagrams. However, if you are not sure you are in view of both a satellite and an earth station you can just put it into the Datagram queue and it will get out one way or the other.

The terminal's backlighting was great. I stood outside at 11 PM in very dim light and found both the display screen and keyboard easy to read. Magellan does caution users that backlighting is a heavy consumer of battery power.

We sent several short messages successfully, include one to the PSN fax service. All were received OK.

The three-foot telescoping antenna on the GSC-100 worked well with a high-power receive signal. You are suppose to be able to remove the telescoping antenna and connect an antenna cable to the unit, but I didn't have time to try that. Almost any 2-meter antenna with a good ground plane should improve operations.

The 9.6v NiCad battery pack takes six hours to charge from the wall socket adapter (per the instruction book). Extra battery packs and a solar panel would be a good idea on a long trip.

Orbcomm now has eight satellite working. That is a great improvement over the limited number of satellites available (only 2) when I was testing the system last year. During my short test day at the Hamfest, the longest I had to wait was two hours between groups of satellite. They tended to appear in sequential groups with gaps between the groups. Considering that only a quarter of the planned satellites are now active, things will get better. When the full constellation is up next year it will only be a few minutes between passes, if any time at all.

Please remember the units are not in production yet. The terminals are still the only real mobile satcom units available (soon), and I'm looking forward to getting my first production units in next month. I think you will be surprised by how easy they are to use and the convenience of a hand-held satcom unit.

BTW, it looks like the PSN pioneer members are getting quite a bargain at $999 compared to some of the prices I have seen advertised on the web.

For folks who can't justify the cost of a full time unit, we will have a few rental units available.

Don