Overview
The MOAS II consists of three parts: the intelligent switch, the server program, and the clients.
Capabilities
Section titled “Capabilities”The MOAS II switch, server, and clients provide significant capabilities.
Suitable antennas
Section titled “Suitable antennas”The client can be set to only display antennas which are usable for the radio and for the frequency the radio is using. The configuration file controls which antennas to display. If an antenna is being used by another radio, that information can also be displayed. The operator will not be able to select that antenna unless it is configured to be shared.
Hot switch protection
Section titled “Hot switch protection”The switch will not change relays for a radio which is transmitting. It will change relays for other radios if it is safe to do so.
Different TX and RX antennas
Section titled “Different TX and RX antennas”Transceivers close the amplifier keying line a few milliseconds before they output RF. This delay is necessary so the amplifier can switch to transmit. If the relays used for antenna switching are fast enough the switch can select a different antenna for transmit than receive. The ability to do this can be configured per antenna pair.
Conflicts
Section titled “Conflicts”Most of the time if a radio is using an antenna then other radios cannot use that antenna. Sometimes other radios cannot use other antennas as well, such as when they have a common feedline. The server will show antennas with conflicts as unavailable and the operator will not be able to select them.
Wait and interrupt modes
Section titled “Wait and interrupt modes”The switch can be configured so that if a radio is transmitting and an operator changes antennas it briefly interrupts the transmission or it waits until the transmission is complete.
Inhibits
Section titled “Inhibits”The switch can be configured so that when one radio transmits it inhibits one or more other radios. The server can set inhibits always, or when two radios are on the same band, or under operator control. The inhibit outputs can be set to inhibit always or only when a radio attempts to transmit.
Alternate paths
Section titled “Alternate paths”There may be multiple ways for an antenna to be connected to a radio. The MOAS server automatically uses a path which is not being used by other stations, if one is available. This is usually invisible to the operator.
Selection by frequency
Section titled “Selection by frequency”Antennas are selected by frequency range. An antenna which covers multiple frequency ranges can use different relays for various parts of the frequency range.
Automatic selection
Section titled “Automatic selection”If a radio is tuned outside of the current frequency range of the antenna it is using, the server will automatically select an antenna suitable for the new frequency.
Antenna systems
Section titled “Antenna systems”An antenna system is a group of antennas such as a stack of yagis. The MOAS II understands about antenna systems and provides methods for selecting antennas within a system.
TX only and RX only antennas
Section titled “TX only and RX only antennas”An antenna can be configured as transmit only or receive only. A transmit only antenna will not be displayed as available for receive and it cannot be selected for receive. A receive only antenna will not be displayed as available for transmit and it cannot be selected for transmit.
Override
Section titled “Override”An antenna can be set so that it may be selected even if it conflicts with antennas selected by other radios. When this override is used the other radios will be assigned antennas which are not in conflict.
Sub-receiver
Section titled “Sub-receiver”A sub-receiver can be configured as an additional radio. The MOAS will select antennas for the sub-receiver.
Shared antennas
Section titled “Shared antennas”An antenna or an antenna system may be shared by more than one radio. The MOAS II supports shared antennas and systems. If an antenna system is shared then changing the selected antennas within the system will affect all users.
Shared transmit antennas
Section titled “Shared transmit antennas”If two or more radios are using inhibits to prevent both from transmitting at the same time, they can use transmit antennas which conflict, including using the same antenna.
If two radios are sharing a transmit antenna and one is listening on a transmit antenna, the MOAS can be configured so that the other station’s receive antenna automatically becomes the alternate antenna. It can also be configured so that the operator can select an alternate antenna.
Alternate antennas
Section titled “Alternate antennas”There is a provision for configuring radios so that when one is transmitting, another is switched to a different receive antenna. This can be used for receiver front end protection when two stations are operating on the same band and antenna separation is limited or when two stations are on a band sharing a transmit antenna.
The MOAS can be configured so that the operator can change which stations cause an alternate antenna to be selected, and these selections can be changed using a function.
Same band protection
Section titled “Same band protection”The server can be configured so that if a radio switches to a frequency within the range of another radio, that radio will not be connected to an antenna. This protects the front end of a radio if an operator inadvertently switches it to a band being used by another radio.
Functions
Section titled “Functions”The server can be configured to make functions available to the client. These include things like storing and recalling an antenna selection, swapping antennas between radios, and setting the RX antenna to the TX antenna.
Rotators
Section titled “Rotators”The server can control rotators. These can be physical rotators, or if an antenna is electrically rotatable, it can be represented as an electrical rotator.
Physical rotators can be connected to any computer on the network using a serial or USB connection. A separate program, MOAS Rotator, controls the serial or USB ports.
Extra, Set, and Reset Relays
Section titled “Extra, Set, and Reset Relays”The server can set relays when a station transmits within a frequency range. The relays can be turned on during transmit and will be off during receive. They can also be turned on or off when a station starts transmitting. This means that when a station starts transmitting it can turn on relays which will remain on until another station starts transmitting which can turn them off.
Status notification
Section titled “Status notification”The server can notify a client when a radio is in transmit or receive state, when it is inhibited, and when the server is unable to communicate with the hardware. To use this the switch must be set to notify the server when transmit/receive state changes.
Scenarios
Section titled “Scenarios”The server can make antennas available depending on conditions such as two radios being on the same band.
Enable and Disable
Section titled “Enable and Disable”A radio can be disabled. When it is disabled it does not have an antenna and it is inhibited. When it becomes enabled an antenna will be selected for it and it will become uninhibited unless something else is inhibiting it.