This page documents some of the key applications available in the Hovergroup svn.
iAcommsDriver
iAcommsDriver provides our standard interface between MOOS and the WHOI uModem. It implements the GOBY uModem driver class and allows other MOOS applications to make use of the modem through several MOOS variables.
Simple Interface
Great for simple applications or human use.
Transmitting
Transmitting is very easy - simply post a string to the variable ACOMMS_TRANSMIT_DATA and the modem will immediately send that data if it is not currently receiving or transmitting data. The variable ACOMMS_DRIVER_STATUS indicates whether the modem is "ready", "transmitting", or "receiving". The transmission rate and destination can be set by posting the the variables ACOMMS_TRANSMIT_RATE and ACOMMS_TRANSMIT_DEST. If sending non-ASCII data, post a binary string to ACOMMS_TRANSMIT_DATA_BINARY instead.
Receiving
To use simple receiving, the "enable_legacy" option must be enabled in the MOOS process config. Whenever a transmission is received, information about the reception is posted to several variables:
- ACOMMS_RECEIVED_DATA - binary string type - contains all the received data. Data from multiple frames is concatenated together, even if frames in the middle are missing.
- ACOMMS_BAD_FRAMES - string type - comma delimited list of bad frame indices
- ACOMMS_SOURCE_ID - double type - integer ID of the transmitting modem
- ACOMMS_DEST_ID - double type - integer ID of the destination modem (0 = broadcast)
- ACOMMS_RATE - double type - integer rate of the transmission
Unified Interface
Sometimes the simple interface is cumbersome because applications have to subscribe to many variable to get enough information about incoming acomms transmissions. With the unified interface, only one variable is required to send or receive data.
Transmitting
Note that the simple transmitting method is supported regardless of the "enable_legacy" setting. Alternatively, use the AcommsTransmission class defined in the HoverAcomms library. Post the serialized object to ACOMMS_TRANSMIT and the acomms driver will set the rate, destination, data, etc. all from the information stored in that object.
Receiving
With each receipt an object of the AcommsReception class defined in the HoverAcomms libary is posted to the binary string ACOMMS_RECEIVED. This posting is still available if "enable_legacy" is turned on.
Logging
Several postings are made specifically for logging purposes, but applications may use them as well. These postings are always enabled.
Transmitting
- ACOMMS_TRANSMITTED_DATA_HEX - string - a hex translation of the transmitted data
- ACOMMS_TRANSMITTED_ALL - string - a loggable serialization of the transmission protobuf
Receiving
- ACOMMS_RECEIVED_ALL - string - a loggable serialization of the reception protobuf
- ACOMMS_RECEIVED_DATA_HEX - string - a hex translation of the received data
- ACOMMS_IMPULSE_RESPONSE - string - self explanatory
Additional Options and Special Rates
Mini Packets - Rate 100
Just a 13-bit packet. If only one byte is provided, it will be packed with a leading 0x00. If two or more bytes are provided, only the first two bytes will be taken and a bitwise and with 0x1f will be performed on the first byte. Examples:
0x6161 --> 0x0161
0x0061 --> 0x0061
0x6100 --> 0x0100
0x61 --> 0x0061
FSK or PSK encoding can be set using the "PSK_minipackets" process config. Default is FSK.
REMUS LBL - Rate 101
A ping that contains no data. Each LBL transponder in the water will yield a range response. As many as four responses are published in comma delimited form to REMUS_LBL_TIMES.
Two Way Ranging - Rate 102
In development.
One Way Ranging
Enabled using the "enable_ranging" process config, this option syncs all transmissions to a PPS pulse provided by PPS. Both sending and receiving modems must have this option enabled to work. If the legacy option is enabled the travel time will be posted to ACOMMS_ONE_WAY_TRAVEL_TIME, otherwise the travel time will be contained in the AcommsReception object.