By Chris de Combe, Manager of Applications Engineering, Ultra Electronics TCS, Ultra Electronics TCS
SubscribeUltra-TCS leads the world in the development and supply of advanced radio relay equipment and subsystems.
Ultra-TCS has supplied the last three generations of LOS radio relay for the US Army and is currently the prime contractor for the provision of upgraded AN/TRC-190 radio relay shelters for the new Joint Network Node (JNN) system. The radio used in this system is the AN/GRC-245 High Capacity Line of Sight (HCLOS) radio. To date Ultra-TCS has built over 2500 software defined AN/GRC-245 radios and fielded communications shelters to signal units in two Army Corps.
Field Deployment of the AN/GRC-245
The AN/GRC-245 was first delivered to the US Army in 2001. This year the radio has undergone a major transformation to change the modem architecture to conform to the U.S. Software Communication Architecture version 2.2 and to incorporate the option of an internal SUPERHIGHWAY IP multiplexer. This new architecture allows new waveforms and features to be added to the radio by software down load. With the embedding of the SUPERHIGHWAY IP multiplexer the radio is able to accept a direct Ethernet input in addition to two serial group inputs. As an option it also can provide encryption for the transmitted traffic.
Enhancing the capability of the AN/GRC-245 radio
Ultra-TCS has supplied both products and turnkey radio relay subsystems to major primes throughout the world. Ultra-TCS provided the radio relay shelter subsystem for the Canadian IRIS project and have recently won a contract to supply the enhanced AN/GRC-245 radio to increase the data capacity of the Canadian Army area communications system to 16 Mb/s with the future option of going to 34 Mb/s.
The value of having a software-defined radio was clearly shown when the Canadian Army requested the capability to communicate with a moving command post vehicle. Ultra-TCS developed a new waveform for the AN/GRC-245 radio that used adaptive equalization and forward error correction to overcome the effects of vehicle motion and multi-path reflections. This new waveform was ported to the existing AN/GRC-245 radio and gave the Canadian Army the required On-the Move (OTM) capability.
The enhanced AN/GRC-245 radio is a multi-band multi-mode software defined radio that allows the operating frequency and waveform to be selected to meet the operational requirement. One of the key features of the radio is its long range and its spectrum efficiency. The amount of spectrum a radio takes to transmit a certain traffic rate is a critical performance measure as spectrum is becoming more and more crowded with the deployment of new systems. The AN/GRC-245 is one of the most spectrum efficient radios available today with its 3.3 b/Hz efficiency.
The ability of the operator to select different waveforms allows the radio to be optimized to the operational scenario. For initial antenna alignment the operator selects a DPSK narrow band waveform that gives additional gain over the normal traffic mode in the radio. This allows the radios to communicate even if the antennas are misaligned.
The Enhanced AN/GRC-245 radio uses the Software Communications architecture (SCA) that was developed by a consortium of U.S Defence contractors under the sponsorship of the Joint Tactical Radio system (JTRS) joint project office. The objective of SCA is to provide an open standard to standardize the internal architecture of software defined radios. This standardization facilitates future flexibility and growth for the product by making it easier to add new waveforms and features.
For operation with traffic the operator has the choice of a spectrum efficient, high capacity waveform supporting up to 34 Mb/s or lower rate more robust waveforms for use when there are communication difficulties.
If communication is required to a mobile command post the operator can select the OTM waveform that supports the high multi-path environment found with transmissions from mobile vehicles. For initial link alignment the operator can select the DPSK waveform, which increase the sensitivity of the radio by about 20dB to permit communication even when the antenna is not properly aligned. The software defined radio architecture allows the same hardware to be used in all these various operational scenarios.
Reliability and maintainability support is an important factor for a radio deployed in a tactical system. The AN/GRC-245 can be maintained by the soldier and is modular allowing field replacement of faulty modules. With the large quantities being built for the US Army the radio has been proven to exceed its predicted MTBF and provides very reliable operation.
