I remember when I first got licensed in June of 1992, reading the Space Operations chapter in my newly
acquired ARRL Handbook. While reading this chapter, I ran across a diagram of an HT being used
through a satellite gateway system. I thought "Wow, you can talk through a satellite with an HT? That's cool!"
I got started in satellite operations by joining the Henry Ford Community College ARC (K8EEH). They had a satellite station so I signed up. A couple of the guys, Mike KF8BE and Mike N8MVP started showing me the ins and outs of satellite operations. I asked them, "Have you guys ever heard a satellite gateway station?" They said "Nope, never heard one." Well, that thought was shuffled back into the file. Since then I've never heard anyone talk about an analog satellite gateway on the satellites. I'd seen few articles published about the concept. But that was four years ago.
Since then I've: set up my own analog and digital satellite station at home, became an AMSAT Area Coordinator, accepted the responsibility of the Southeast Michigan AMSAT net from Rich, N8IWJ, and even set up an Internet web page for the local AMSAT net. Hams in the area have asked to visit my satellite station or the station at Henry Ford Community College so they could see what this satellite stuff was all about. There have even been a few hams who have set up their own satellite stations as a result of these efforts. This is what it's all about, isn't it? Spread the word about what you can do on amateur satellites and hopefully recruit some new members for AMSAT-NA. This, after all is in all our best interest. More members means more financial support which results in more satellites for all of us to play on! I'm always talking about satellite operations to folks on the local repeaters and sometimes I probably bore some people. The gears are always turning; how can I get more hams involved in amateur satellite operations? Hey, that section that I read about in the ARRL Handbook. The satellite gateway!
I've recently been involved with Dan, N8DJP, on his repeater projects. I'm an electronics technician working in the automotive industry and was interested in learning more about the RF end of electronics. Dan is very knowledgeable in this area and has been converting commercial radio gear to amateur use for years, including converting Motorola Micor commercial repeaters for local ham repeater use. I told Dan about the satellite gateway concept that I had read about four years previously and said I was interested in setting up such a system using my satellite station and his 2 meter repeater. He thought this was a great idea. So the quest began.
The first thing I had to think about was how to control everything. WiSP, by Chris Jackson, G7UPN, and available from AMSAT, is a very versatile program, perfect for automation of a satellite station. WiSP is primarily used for digital satellite operations but it's also perfect for the automation of doppler shift and antenna control. I wanted to be able to control the satellite gateway from a remote location and not have to worry about tracking the satellites manually. With WiSP, my station was already running automatically on the digital satellites. It utilizes the Kansas City Tracker/Tuner card to control my Yaesu G5400 antenna rotor and Icom IC820H dual-band all- mode radio. I added the satellite I chose for the gateway, OSCAR 27, to the schedule.
WiSP will tune the satellite radio to the right frequencies, correct for doppler, and at the same time control the az/el rotor while the satellite is in view. This was all I had to do to automate the satellite station. WiSP also has the ability to play a prerecorded sound (.WAV) file before the satellite comes up. The sound card is interfaced to the gateway and plays this prerecorded sound file over the repeater to announce that the satellite will be at the horizon in one minute.
The satellite station was now operational, but how can I interface this to the repeater? I needed something to control this process and a way to ID the station to meet Part 97 requirements. I pondered this idea for a while and found that Jim, WB2REM, had already developed a great controller to handle this. His design was published in the January 1995 issue of QST and I thought about using his device. However, this would have involved either making my own PC board or wire wrapping the circuit. I had not made PC board layouts this complex and didn't have the equipment to do it correctly. Previous experience told me that one false move with the wrapping tool meant hours of debugging. Building a controller shouldn't be that risky.
I also looked into using a radio linking system, but this didn't have all the features I needed. I spoke to Dan,
N8DJP, about my dilemma and he told me about a repeater controller available from Micro Computer Concepts,
which he and another repeater trustee used on a couple of new repeaters they put up. The RC-100 was $130 and
provided all the features I needed for my satellite gateway. These features included repeater input/output to
interface to the 2 meter repeater, remote base to interface to the satellite radio, CW ID'er, DTMF remote control,
and other features. 
With the station controller problem solved, I needed a 220 MHz radio to link into the repeater. The repeater I'm linking to has a 220 remote base that is used to receive the downlink audio of the satellite from my station. A 2 meter receiver was also necessary to monitor the repeater output frequency. The repeater input audio could then be uplinked to the satellite.
But there is a problem with this method. If left this way, there would be an endless loop with my link permanently engaging the repeater. To solve this problem and eliminate repeater hang time from being transmitted up to the satellite, a PL decoder needed to be installed on my 2 meter receiver. Also, a PL encoder had to be installed on the repeater transmitter with the PL active only when a user is heard on the repeater input frequency. With this configuration, the only way other satellite users would know you are on a repeater uplinking to the satellite is if you told them or if the repeater happened to ID while the user was talking. The PL acts as a filter, keeping the repeater hang time, repeater voice IDs or messages from being heard over the satellite.
I had all the necessary hardware, now to hook it up. The first thing which needed to do be done was to set up the repeater link portion of the gateway. The gateway controller needed a source for receive audio and COS. (COS is a logic signal which tells the controller to key the transmitter when receive audio is present.) In my configuration I took the receive audio from the input side of the volume control and the COS logic signal from the PL board on the 2 meter receiver.
The transmitter also needed to be connected and, in this case, a 220 HT, (a used Icom IC3AT I picked up for $140), was interfaced to the controller. The controller supplied transmit audio out and PTT logic. These signals were connected out to the microphone jack, completing the repeater link side.
Next I needed to interface the satellite radio to the controller. The remote base side of the controller was used for this process by connecting the remote base transmit audio to the IC820H, through the mic input on the microphone jack. The controller's remote base PTT logic signal also needed to be connected to the PTT input on the 820's microphone jack.
For the downlink receiver, the satellite radio's audio out (which is also available on the microphone jack on the Icom IC-820H) was connected to the controller's remote base receive audio input. The remote base COS logic was also needed and, on the 820, this logic signal is available on the data jack on the back of the radio. (The receive LED indicator lamp on a satellite radio could also be used to supply this logic signal.) Once this connection was made, I set audio levels on the radios and the controller, and programmed the controller. See fig. 1 block diagram for the controller-to-radio interface wiring.
Since I've had this gateway in operation (approximately 3 weeks at this writing), there has been a great amount of interest. It's nice to hear something different on the repeater than the usual traffic. Some of the hams in the area who I thought could have cared less about satellite operations have become very enthused about this gateway. Some have even talked about setting up their own satellite stations. And just think, I haven't even linked to any DX birds yet!
I hope this article has given enough information so others can set up a similar operation. My cost for this was under $400. For satellite operators who are already operating on the birds with automated stations, you could also set up a satellite gateway with little added expense and share your enthusiasm of satellite operations with other ham radio operators.
