There are four aspects to this project which are:
- Signal Conditioning and data gathering. This involved adapting signal levels so that they can be monitored by an A/D converter, and also how to handle digital I/O as well.
- Transmission the monitored values needed to be sent somewhere where they could be analyzed further for fault conditions. Several methods presented themselves as being viable, including a USB or IP connection.
- Configuration and alarm generation. This involved designing some receiving software which is web based, including how to configure it to determine an alarm state.
- Alarm delivery Next was how to deliver an alarm. It was decided that e-mail is the best alternative, and using an e-mail to sip portal it can also be sent to an IP phone, provided the portal and extension are on the same PBX.
As the MaplePi board already had an 8 channel A/D converter, introducing analog monitoring was a matter of adding the signal conditioning. An analog break out board (BOB) was designed which mated directly with the MaplePi, and provided signal conditioning and buffering, with one dedicated channel for the battery voltage, and another for the FPGA temperature. This design was deprecated when the Intel FPGA became scarce.
To replace the BOB and provide similar functionality for the MapleDroid platform and existing Allstar installations, the PUTSI (PIC USB Telecommunications System Interface) was created. It has both a USB and WIFI connection, and supports the existing protocol in Allstar as well as IP based telemetry using the USRP protocol.
Finally, a web based monitoring system was designed and implemented as an adjunct to the digital linking system, which enabled configuration and alarm generation from a web browser. The software is currently deployed on a server on the PNW AREDN network, and is supported by the Alberta Digital Radio Communications Society.
Below is a sample alarm message sent to a Polycom IP phone.
