(Published Defence Security India, Aug 2014)
A warship at sea functions like a huge sea creature in respect of a majority of its functions. For example, there is a need for a ship to see, listen, and communicate; it uses Radars, Sonars and Communication equipment for these tasks. The overall goal of the warship is to identify and eliminate the threats arising at sea, thus all the equipment on board a warship is required to function in unison to achieve this aim. Emphasis in this article would be on Communication equipment, discussion on technological aspects of Radars and Sonars would be limited to essentials only.
The first official message from a ship to a shore station, 20 miles away, was sent in 1899, the first use of radiotelephone between ships was reported in 1916. However, until the installation of superhetrodyne receivers on board ships in 1931, radio communication was considered unreliable. Radio teletypewriter transmissions between ships were carried out successfully in 1944, and the first FAX (radiophoto) transmission was that of the surrender document that ended WW II!
Navies use visual, sound, and electrical means for communications. Telecommunication includes in its ambit transmission, emission, signals, images, sounds, and intelligence information by visual, oral, wire, radio, or other electronic systems.
Ships use radiotelephony because of its ease of operation, directness, and convenience. In the navy, it is used for communication between ship-to-ship, ship-to-shore, shore-to-ship, air-to-ship, ship-to-air, air-to-ground, and ground-to-air. The most important use of radiotelephone is in short-range tactical communication.
Radio communication has become a specialized field of electronics. Naval ships toady have the ability to utilize ship-to-shore, ship-to-ship, and ship-to-air, communication circuits. Naval communication systems vary in complexity depending upon their role, compatibility, and flexibility. Due to scarcity of space on board a ship, the communication equipment is spread across the ship’s compartments; however, it is ensured that the sets are capable of operating separately as well as concurrently. Complex interconnections provide the ability of selectively switching different configurations.
Radiofrequency bands commonly used for naval communication include, very high frequency and above, high frequencies, medium frequency, low frequency, very low frequency, and extremely low-frequency.
Very High Frequency and above (30 MHZ – 300 MHZ) are only used for line of sight communication as ground range is very less. High Frequency, HF (3 MHZ – 30 MHZ), has been used by the navy since WW I. HF is used for point-to-point, ship to shore, ground to air and fleet broadcast (one way only).Medium Frequency, MF ( 300 KHZ – 3 MHZ), bands in the upper and lower portions of MF are used by the Navy for ground wave transmission, since the commercial band generally extends from 535 to 1605 kilohertz. Low Frequency, LF (30 KHZ – 300 KHZ), band has only a very small part of the radio-frequency spectrum. Low-frequency transmitting installations have large physical size and high construction and maintenance costs. However, Low-frequency waves are not so seriously affected during periods of ionospheric disturbance when communications at the high frequencies are disrupted. This makes LF useful in the northern latitudes. Very Low Frequency, VLF (3 KHZ – 30 KHZ) provides a highly reliable path for communications over and under all oceans and seas of the world. Currently all naval VLF transmitters are used for fleet communications or navigation. VLF transmission is normally a one-way transmission, a broadcast, where no reply is required. A VLF broadcast of standard time and frequency signals provides precision for the operation of single-sideband transmissions, synchronous cryptographic devices, and decoding devices. It is used as a backup to shortwave communications black out by nuclear activity, as well as in communications to satellites. Extremely Low Frequency, ELF (Up to 300 HZ), communications are used by the US Navy to send short “phonetic letter spelled out” (PLSO) messages (one way communication) from operating authorities to submarines operating at normal mission speeds and depths. ELF penetrates ocean depths to several hundred feet with little signal loss.
Wireless Link Interface Communications
U.S. Navy has already begun the deployment of wireless link interface technology on board 97 of its ships for maritime interception operations. The wireless system will allow communication directly with boarding teams several miles away. Interdiction units will be able to transmit biometrics data, scanned documents, digital photos, and emails, back to the ship using the data link. US navy has successfully tested microwave-based wireless wide-area network (WWAN) between ships to enable incorporation of Long-Term Evolution (LTE) standard, generally referred to as 4G LTE. It is a standard for high-speed communications among mobile devices, and transmits data at around 100 megabits/sec, fast enough to handle images and videos as well as voice and text. The WWAN would augment the existing satellite-based communications. The LTE network would let sailors on ships receive real-time video streaming from air nodes mounted on helicopters, which in turn would permit officers to make accurate decisions. Oceus Networks is the likely provider of the systems.
DCNS has developed SySmart, a commercial wireless communications and tracking system. It enables exchange of video, voice, and data wirelessly from anywhere on board a ship using handheld devices. Internet linked video and infrared cameras and other shipboard sensors can be accessed by the sailors. The system is built around existing Ethernet systems and other proprietary wireless networks. It has been successfully tested on French naval ships and is to be incorporated in the next generation of French submarines in 2017.
Rohde & Schwarz in Europe was commissioned to design and build a navy-wide communications network encompassing shore stations, corvettes, patrol boats, landing craft of many sizes and with diverse applications, coastal mine hunters, and maritime patrol aircraft (MPA). Tailored voice and data communications solutions have been defined for shipboard internal communications and external line-of-sight (LOS) and beyond-line-of-sight (BLOS) radio communications. A navy-wide military message handling system (MMHS) covers both strategic and tactical communications. Proprietary applications supplement the STANAG protocols to include chat and e-mail functionality. In addition, HF and VHF/UHF solutions for IP-based services have been incorporated. Different subsystems for capabilities such as telephone calls, announcements, alarms, internal tactical communications on the ship, message handling, and radio equipment have been integrated into an overall system. From a single workstation, it would be possible, to take part in the ship’s internal communications as well as in external voice & data communications and to manage & control applications and devices.
The French Navy has also selected Rohde & Schwarz to provide R&S®M3SR radio communications systems for their newest nuclear submarines. The Spanish Navy also decided to equip their latest tactical submarines with Rohde & Schwarz radio communications systems. Rohde & Schwarz also provides worldwide communications systems for different kinds of aircraft carriers. The R&S®M3SR Series4400 is used on the newest and biggest ‘aircraft carrier generation’ that the United Kingdom’s Royal Navy operates.
Vitavox have been providing the world’s largest navies with military communications equipment since 1933. The audio equipment provided by Vitavox can be used in a variety of applications, both above and below deck as well as above and below surface.
Communication Systems-Indian Navy
The Indian Navy is using indigenous systems extensively on its warships, some note worthy systems already on board warships and scheduled for fitment on ships under production are manufactured by BEL, India they are:-
-ATM Based Integrated Shipboard Data Network (AISDN), it is a multi-services shipboard network designed to converge all voice traffic, real time video and traditional data communications onto a single broadband infrastructure. It is a flexible, triple redundant, modular and reliable network supporting multiple services for naval ships. It integrates various equipment and systems on board namely EW Systems, Radars, Sonars, CAIO (Computer Aided Information Organization), Fire Control Systems, and a number of other equipment for Ship’s Household Data (SHHD). It integrates all sensors, weapons, and communication services onto one single broadband network. It provides integrated and simultaneous transmission of voice, video and data. It has high system capacity and flexibility and uses fiber optic cable as physical medium.
-Composite Communication System (CCS) Mk III is a new generation ATM based communication system that provides ship-to-ship, ship to shore and ship to air communication. It is designed as a voice and data integrated network providing connectivity between radio equipment and remote user onboard for accessing and monitoring and control of radio equipment. The system is highly flexible and can be configured for all classes of ships. CCS Mk III consists of Control & Monitoring Subsystems (CMS), which controls and monitors the entire network and enables operation of radios from remote positions with optimum usage of facilities. Its subsystems are:-
MF Subsystem, it has telegraphy communication and monitors maritime distress frequency.
HF Subsystem, it has long-range communication on voice, telegraphy & teletype (ship-to-shore and ship-to-ship) and receives broadcast transmissions.
VHF / UHF Subsystem, Medium range communication on voice, telegraphy & teletype (ship-to-shore and ship-to-air).
RATT Subsystem, it facilitates teleprinter & telegraphic communication from a ship via radio or land / shoreline.
-Versatile Communication System (VCS) Mk III is a versatile system designed to provide internal communication facilities and display of status of various equipment and systems onboard naval ships. The system is highly flexible and re-configurable and can be configured for all classes of ships. It provides, integrated data (Status and Control) and Voice communication from a single position on IVCS, it uses VOIP technology for Voice & Data communication, it interfaces with the ATM based integrated data network (AISDN) onboard the ship; it reduces wiring and interconnections in the system.
Sonar and Radars
The other important sensors on a warship for underwater and above water threat detection are the Sonar and the Radar. It is not intended to discuss the general technical details of such systems. However, few of the Sonars and Radars frequently in news are being briefly described below.
-Thales Underwater Systems has developed and produced Sonar 2087.
It has been designed to be a variable depth, towed active and passive Sonar system that performs in conjunction with Sonar 2050 bow-mounted active sonar on UK’s Type 23 frigates. Digital technology in signal processing and COTS hardware has been used extensively. It is claimed that S2087 will be suitable for both, littoral environments and Deep Ocean.
-Raytheon has developed the AN/SQQ-90 tactical sonar suite for the US Navy’s DDG 1000-class multi-mission destroyer. The AN/SQQ-90 comprises of the AN/SQS-61 hull-mounted high-frequency sonar, AN/SQS-60 hull-mounted mid-frequency sonar, and the AN/SQR-20 multi-function towed array sonar and handling system.
-Atlas Elektronik will supply Active Towed Array Sonar, ATAS to the Indian Navy, which will equip the Delhi and Talwar class ships. ATAS would be subsequently manufactured in India under cooperation with BEL.
-EdgeTech, has delivered 12 advanced side scan sonar systems (mine warfare) for the Indian Navy.
-Enterprise Air Surveillance Radar (EASR) is a development program for replacement for the SPS-48 and SPS-49 air surveillance radars currently on board US Navy’s amphibious ships and aircraft carriers by the 2020. Northrop Grumman has been awarded an 18-month contract for the study of the EASR requirement. The new radar system will utilize technologies from the AN/TPS-80 Ground /Air Task-Oriented Radar (G/ATOR) program.
-Empar (European Multifunction Phased Array Radar) is a G-band, multifunction, active phased array radar being developed by Selex for the Italian Navy and French Navy. Its rotating antenna at 60 rpm provides continuous surveillance, tracking, and weapons fire control. The Empar radar system will be integrated on the Horizon frigates ordered by Italy and France and the Italian Navy’s Conte di Cavour.
-Raytheon’s AN/SPY-5 is an X-band multi-tracking, target-illuminating system for surface combatants that can simultaneously search, detect, and precisely track multiple surface and air threats. The SPY-5 is an open architecture, phased-array radar system, providing an advanced self-defense solution for small and large surface ships operating in the littorals and other maritime environments. A single radar system consists of three 120-degree beam faces providing full 360-degree azimuth coverage. The mission capabilities include low-altitude horizon search; focused volume search; surface search; missile and surface gunfire control; simultaneous threat illumination; and missile midcourse guidance and terminal homing. It is compatible with all digital combat management systems, and the radar’s range, accuracy and beam agility enable the full performance of the Evolved Sea Sparrow Missile (ESSM). SPY-5’s size, weight and overall self-defense capabilities make it equally well suited for large-deck aircraft carriers and amphibious assault ships as well as corvettes.
Indigenous Sonars and Radars with Indian Navy.
Indigenous Sonars and Radars held by the Indian Navy are manufactured by BEL. Two important Sonars manufactured by BEL are the Advanced Active cum Passive Integrated Sonar System (HUMSA NG) and the Integrated Submarine Sonar (USHUS).
-HUMSA-NG is an advanced Active cum Passive integrated sonar system to be fitted on a wide variety of Indian Navy platforms such as the Project 17, Project 15A and Project 28 class ships. HUMSA-NG is an advanced version of the existing HUMSA sonar presently fitted on P16, P15, Ranjit and Talwar Class of ships. The HUMSA (NG) is designed for enhancing the system performance, reliability, and maintainability. It is capable of detecting, localizing, classifying and tracking sub-surface targets in both active and passive modes. The system provides simultaneous long-range detection in active and passive modes. The sonar is capable of localization and automatic tracking of up to eight targets in both active and passive modes. The sonar integrates the operation of the UWT and XBT systems. The system is integrated with FCS systems such as IAC MOD ‘C and CAIO for exchange of relevant information.
-Integrated Submarine Sonar (USHUS) is used to detect, localize and classify underwater submerged and surface targets through passive listening, interception of signals and active transmissions of acoustics signals. It has both analog and digital external system interface. It is modular and rugged in design with upgradeable performance features. Its passive sonar has preformed beams in azimuth and in three vertical directions using ASICS. It can auto track six targets. Its active sonar has CW and LFM modes of transmission with three selective pulse widths, high source level, low frequency planar transducer array & complex demodulation, replica correlation for Doppler and range estimation. Its intercept sonar can provide early warning long range target detection, all round coverage in three bands, FFT, and Spectral processing. The underwater communication system has multiple mode acoustic communication in dual frequency to meet NATO and other requirements, voice, telegraph, data, and message modes of operation. Its obstacle avoidance sonar is a high frequency short range sonar with rectangular transducer array and its transmission covers three sectors of 30° each.
Some of the indigenous Radars manufactured by BEL, India are-
-L- Band Surveillance Radar, RAWL02 Mk-III, is long-range L band surveillance radar for detection of air and surface targets. It has a roll and pitch stabilized antenna platform, Synthesizer controlled transmitter with TWT amplifier, state of art video extractor track management system based on COTs technology, low noise receiver combined with split pulse and matched dynamic range compression, ECCM capability and a range of 270 Km.
-3D Surveillance Radar, REVATHI, is a state-of-the-art, S-band, Track-While-Scan (TWS) radar designed to effectively play the role of a medium range surveillance radar mounted on a stabilized platform for detection of air and surface targets. It has ECCM features, integrated IFF Mk XI , stabilization against roll & pitch, and remote transmission of data of tracks & plots over LAN for interface with external systems.
-Active & Passive Radar for Navigation & Attack (APARNA), is designed to detect surface targets, furnish target data to weapon computer for missile firing at these targets in the autonomous mode from the ship. The radar system is provided with two transmitter–receiver channels i.e. the first or main channel and the second or navigational channel. The two channels differ in transmitter peak power, pulse width etc.
Consolidated Antennas and Sensors
Communication technology developments to provide ever-increasing requirements of multiple bands and bandwidths, foresee a need for large rotating antennas. These pose several problems on board warships like space availability, electromagnetic interference and increase in ships radar signature. The trend is tilting towards development of single unit consolidating antennas and sensors. Thales Netherlands is developing its integrated sensor and communications suite, which will house radio and data-link communication systems, radar and electro-optical subsystems and IFF in a single unit. The US Navy has awarded 18 contracts to develop integration and management technology for radio frequency radar and communications functions. The objective of the advanced multifunction radio frequency concept is the integration of radar, electronic warfare and communications into a common set of apparatus with signal and data processing, signal generation and display hardware.
Thus from the above it can be appreciated that the field of sensors for utilization on a warship is an ever expanding one, with new features and capabilities adapted from the commercial world being added practically every hour. To say the least the features and capabilities of various war ship sensors by end of this decade are going to be phenomenal.