What is OpenAMIP?
OpenAMIP is an IP based protocol that enables the exchange of data between an Antenna Controller Unit (ACU) and the iDirect satellite modem. Developed in 2006 as an open source solution by iDirect for the integration of information between the ACU and satellite modem without any user interaction.
Prior to the development of openAMIP, there was very little collaboration between VSAT modem manufacturers and the stabilised antenna industry. The interfacing between the ACU and modem was left to the satellite service providers by proprietary coding by software engineers to solve or by changing the satellite details manually. iDirect worked with the leading antenna manufacturers at the time to develop an open source protocol that would be adapted industry wide.
OpenAMIP, which is a ASCII based protocol, allows the satellite modem or router to command the antenna and enables the use of Automatic Beam Selection (ABS), which transfers connectivity from one satellite beam to the next as a vessel passes through multiple footprints. In addition, OpenAMIP and ABS enable service providers and their customers to meet government regulations by commanding the antenna to mute the signal in no transmit zones or if the ACU detects that the antenna is mis-pointed to prevent Adjacent Satellite Interference (ASI).
The major stabilized antenna manufacturers like Cobham (Sea Tel), Intellian and Orbit have implemented openAMIP to control the antenna with some other antenna manufactures opting to telnet in to the modem to issue commands and receive information.
A two way exchange of information between the ACU and modem:
- GPS location
- Satellite Longitude
- LNB Local Oscillator Frequency (LO)
- Tracking Frequency
- Modem lock signal
- Tx Mute
Automatic Beam Selection (ABS)
When a vessel is transiting between satellite beams, or the modems drops out of network due to low receive signal level (rain fade, line of sight blockage, etc.), the modem can command the antenna to search and then track an alternative satellite by openAMIP. The user or Network Operations Centre (NOC) can also issue a switch beam command to the modem.
A map server can be loaded on to the Network Management System (NMS) to control switching between beams based on cost, satellite availability, no transmit zones and satellite footprints. The map server also calculate the initial Tx power of the maritime VSAT system required at a given location for a certain beam.
It is possible to switch beams locally at the iDirect modem CLI and it simple to execute with the following commands:
> beamselector list 406 is currently selected 509 = T11E 466 = E70A 408 = E17B 406 = AS4 > beamselector 408 switch -f > beamselector lock
There may be slight changes to the commands depending on the firmware version used, beamselector ? will display the list of commands available.
Mobile GPS Location
The remote site is set to be mobile in iBuilder Geo Location page. When the option file is updated with this setting the remote will will receive it’s GPS location from the antenna. Some older ACU use a serial connection otherwise it uses IP.
To check that the modem is receiving the GPS location the command latlong can be used on the CLI.
> latlong latlong = 10.4475 S, 105.6904 E
The iDirect option file that is loaded on to the modem contains the openAMIP settings under [ANTENNA]. If you think that are is an issue with openAMIP then check the IP address and port number are correct, they should match the ACU settings.
addr = 192.168.0.3
connect_timeout = 30
dedicated_interface = eth0
manufacturer = OpenAMIP
max_skew = 90.000000
model = OpenAMIP
port = 2002