The CESMO protocol was trialled during NATO’s Unified Vision 2018 interoperability tests. This diagram clearly illustrates how ESM data will flow in real time between platforms greatly accelerating the identification and location of hostile radars.

NATO’s CESMO initiative is an important step forward in providing real-time RF data during operations to help the speedy avoidance or engagement of RF threats.

The forthcoming June/July print edition of Armada International includes an article examining the North Atlantic Treaty Organisation’s (NATO’s) Cooperative Electronic Support Measure Operations (CESMO) protocol. We caught up with John Colbran, a senior analyst within the electronic warfare and sensors branch at NATO’s Intelligence, Surveillance and Reconnaissance Support Centre. to get an insight on the programme’s scope and progress to date.

Although a long-running initiative within the alliance CESMO was formalised by NATO’s Standardisation Agreement 4658 (STANAG-4658) ratified in 2015. CESMO is an interoperability method and protocol which uses IP (Internet Protocol) messaging transmitted using existing air-to-air and air-to-ground/ground-to-air communications, notes a written statement from the UK’s Defence Science and Technology Laboratory (DSTL) which is heavily involved in CESMO’s development. In a nutshell, CESMO provides a real-time depiction of the location of hostile ground-based air surveillance and fire-control/ground-controlled interception radars during air operations. Mr. Colbran says that the ability to pinpoint the location of hostile radars in real time, and to share that information with other platforms, is crucial: “When this sort of data-sharing is done post mission, mobile threats may have relocated or left the area.”

Existing Networks

One of the clever aspects of CESMO is that NATO has not needed to devise a new datalink or communications network to share this information. Any existing link which can handle IP data can handle CESMO traffic: “It can work over any communications link supporting IP, secured to the security classification of the data being shared,” the statement continued: “It has been designed to work over the low data rate and intermittent communications links often associated with mobile military platforms, but will operate over faster links as well.” During CESMO development trials this included using standard IDM (Improved Data Modem) equipment encrypting the IP traffic and carrying this over standard air-to-air Ultra High Frequency (UHF: 300 megahertz/MHz to three gigahertz) communications. CESMO uses triangulation and Time Difference of Arrival (TDOA) techniques to ascertain the position of a hostile emitter whether that be a radar or communications device, indicating CESMO’s applicability to the land and sea domains.

The key contribution CESMO can make, particularly for the air battle, is providing real-time details of hostile emitters active in the theatre of operations. The alliance’s Link-16 Tactical Data Link (960MHz to 1.215GHz) used extensively during air operations can handle some tactical traffic concerning Electronic Warfare (EW), typically J14 and J14.0 series messages which relate to emitter parametric information and EW control co-ordination, respectively.

The DSTL statement says that CESMO’s role in supporting operations starts with the drafting of a list of all participating platforms and their accompanying sensors, notably their Radar Warning Receivers (RWRs) and Electronic Support Measures (ESMs). These platforms are then supplied with a list of hostile emitters expected to be encountered. This list can be derived from initial intelligence gathering efforts according to the priorities of the operation or individual mission. As the platforms undertake their missions their RWRs and ESMs listen out for these radars. As they are detected the respective lines of bearing from the platforms to the radar is calculated in real time by the sensors and reported in IP format over links. This information reaches the CESMO Fusion and Coordination (CFC) node which acts as the ‘clearing house’ for the data. The CFC then computes the position of the radar via triangulation and uses CESMO to send out an alert to the aircraft regarding its location. Once this is known the radar can be avoided, or engaged kinetically or electronically. Usefully, the CFC can also receive electronic support information regarding new radars in the theatre of operations via CESMO which may not have been on the initial electronic order of battle, and perform the same identification and location processes. This makes the CESMO architecture highly responsive: “the key advantage of CESMO is the timeliness of its information,” Mr. Colbran continues.


An updated version of STANAG-4658 will be ratified later this year reflecting additional CESMO experiments performed by NATO. CESMO has been used by individual states but presently “there is no NATO operational CESMO capability” says Mr. Colbran. Such a step will be contingent on “preparing NATO communications networks to support CESMO (which) would be key to realising CESMO’s potential within NATO.” This is something that could occur over the next five years as STANAG-4658 continues to be evolve.

by Dr. Thomas Withington