Repeaters: Repeater Systems
So you'd think repeaters are near invincible because their signals should be able to bounce from repeater to repeater. But alas, they have to deal with obstacles and a need for extended range as well.
To deal with both of these issues repeaters use remote receivers. The signals from these receivers are then transmitted by an auxiliary station to the repeater's transmitter site for retransmission. Middle-man if you will.
Auxiliary stations are not used for direct contacts and most are on the 1.25 meter and 70cm bands.
Repeaters can also be linked to other repeaters - that is they share the audio signals each receives and then retransmits them over a wider area than any one repeater can cover. Repeaters also retransmit signals on other bands. So for example a 2m repeater linked to a 70cm repeater allows stations on either band to contact each other. And if they're colocated (at the same site), the repeaters can be physically linked together with cables or with control links.
Control links consist of a transmitter and receiver that only relay audio and control signals between repeaters. The signals carried by the links control various repeater features - usually enabling or disabling the retransmission of signals by the linked repeaters.
Repeater networks or systems are made up of several linked repeaters that can be many miles apart. Control signals are used to configure the way in which the network relays signals between repeaters.
If you become a regular user of a linked repeater system, you may want to join the group operating the repeaters. You can be authorized to use the control codes to configure the repeater network and even perform basic maintenance and test functions.
To use control codes of any sort on the repeater requires that your transceiver be able to generate the appropriate tones or tone sequences.
The repeater controller is a piece of equipment that regularly sends the repeater ID, operates the time-out timer, switches the transmitter on and off and so forth. Modern controllers have microprocessors and sophisticated electronics that provide advanced features: synthesized voice announcements, time/date, weather conditions, and other things.
Sometimes repeaters have coverage where cell phones don't. So the system that lets hams make a phone call through a repeater is called autopatch - short for automatic phone patch (connection)
When activated by the proper control code sequence, this system connects the repeater's transmitter and receiver to the phone line and you'll hear a dial tone over the air. The ham then dials the number by pressing the PTT switch and pressing numeric keys on the radio. From there it's just like a regular telephone call except that you have to press the PTT switch to talk and you can't talk and listen at the same time.
When the called party picks up the phone, ID the call as being via ham radio to avoid confusing and prohibited transmissions.
