Difference between revisions of "DNVT2IP"
| Line 45: | Line 45: | ||
# Custom-designed interface board. | # Custom-designed interface board. | ||
| − | # Raspberry Pi Model B v. 2.0 board to provide controlling processor and network interface. | + | # [http://www.raspberrypi.org Raspberry Pi] [http://www.sparkfun.com/products/11546 Model B v. 2.0] board to provide controlling processor and network interface. |
# An enclosure to protect the assembly. | # An enclosure to protect the assembly. | ||
# External power supply, commonly a 12V output "wall wart" adapter. | # External power supply, commonly a 12V output "wall wart" adapter. | ||
| Line 54: | Line 54: | ||
# Isolated 48VDC power supply to power connected DNVT over 4-wire interface. ''TBD: Do both pairs need power supplied, or just one pair?'' | # Isolated 48VDC power supply to power connected DNVT over 4-wire interface. ''TBD: Do both pairs need power supplied, or just one pair?'' | ||
# Regulators to power on-board hardware and connected Raspberry Pi board from an external 12VDC source. | # Regulators to power on-board hardware and connected Raspberry Pi board from an external 12VDC source. | ||
| − | # Field-Programmable Gate Array (FPGA) to implement low-level signaling, code detection and generation, | + | # Field-Programmable Gate Array ([[Wikipedia:FPGA|FPGA]]) to implement low-level signaling, code detection and generation, [[Wikipedia:Codec|codecs]], and control/data interfaces to the Raspberry Pi board. ''Probably a [http://www.xilinx.com/products/silicon-devices/fpga/spartan-6/index.htm Xilinx Spartan 6] family device?'' |
Revision as of 20:47, 27 May 2013
DNVT2IP is an open-source hardware + software project released under
GNU Public License version 3. Its primary goal is to provide an
adapter to interface military surplus Digital Nonsecure Voice Terminals
(DNVTs) to Internet Protocol (IP) networks, specifically for use as
Voice Over Internet Protocol (VoIP) phones using Session Initiation
Protocol (SIP). Supported DNVTs include:
- TA-954/TT
- TA-1035/U
- TA-1042A/U
The primary source repository for the project is located at:
This page is the primary documentation site for the project, with its original home located at:
DNVTs are digital field telephones using a 4-wire interface with signaling at 16kbps or 32kbps. Each wire pair carries data in one direction, i.e. one pair of binding posts at each end is a transmit output, and the other is a receive input. The devices may be powered over the 4-wire interface (called "Common Battery (CB)" mode), or may be locally powered (called "Local Battery (LB)") mode when used in pairs without a telephone exchange. TBD: TA-1042A/U supports LB mode, but TA-954/TT and TA-1035/U may or may not.
Signaling and operating states are paritally documented in IEEE Transactions on Communications, Vol. COM-29, No. 11, November 1981, pages 1609 through 1614:
The above article is available for purchase, but is not included here due to copyright restrictions. The article provides considerable insight into the DNVT signaling, but does not provide sufficient details to implement compatible hardware. Thus, reverse-engineering of the DNVT signaling protocol will be necessary in order to generate an open specification for this project.
The hardware portion of this project shall consist of four major components:
- Custom-designed interface board.
- Raspberry Pi Model B v. 2.0 board to provide controlling processor and network interface.
- An enclosure to protect the assembly.
- External power supply, commonly a 12V output "wall wart" adapter.
The custom-designed interface board shall inclue the following major features:
- Electrical interface to the DNVT with suitable filtering, line driver and receiver, galvanic isolation, and fault protection.
- Isolated 48VDC power supply to power connected DNVT over 4-wire interface. TBD: Do both pairs need power supplied, or just one pair?
- Regulators to power on-board hardware and connected Raspberry Pi board from an external 12VDC source.
- Field-Programmable Gate Array (FPGA) to implement low-level signaling, code detection and generation, codecs, and control/data interfaces to the Raspberry Pi board. Probably a Xilinx Spartan 6 family device?