When it comes to EW (Electronic Warfare) the Chinese Navy has one major disadvantage, it’s relatively small and constricted coastline compared to the United States. This limits the areas where new navy electronic systems can be tested over water without electronic surveillance by foreign nations. The American military has the largest and most experienced force of long-range electronic surveillance aircraft. What exactly these aircraft are looking for and, more importantly, what they discover, is kept secret. Sometimes the results of discoveries by these surveillance aircraft, and ships, does become public. Sort of. A recent example was the realization, mainly by journalists and analysts that two 7th Fleet destroyers damaged during widely reported 2017 collisions, had an additional EW (Electronic Warfare) device mounted on them that was not present on American warships operating in other parts of the world.
It was known that warships assigned to the West Pacific (7th Fleet) get some China-specific electronic sensors and jammers to deal with Chinese weapons that are not exported and expected to only reveal their abilities in an actual shooting war. All U.S. warships have a basic version of the AN/SLQ-32 (or "Slick 32") that can monitor enemy electronic transmissions in real-time, identify them as much as it can and instantly share the information with nearby U.S. warships. During the Cold War Russia was the primary naval opponent equipped with advanced electronic sensors and weapons and Slick 32 capabilities were installed on American ships expected to encounter Russians.
Slick 32 first appeared in the late 1970s and since then has quietly evolved to deal with new threats. That development continued after the Cold War ended in 1991 and the Russian threat largely evaporated, along with most of the huge Russian fleet. By the late 1990s, it became apparent that the Chinese were picking up where the former Soviet Union left off and since then AN/SLQ-32 has been evolving more rapidly to keep up with new Chinese capabilities. One of the China-specific items added to the U.S. Pacific based warships is the AN/SLQ-59. This is a TEWM (Transportable Electronic Warfare Module) device only found on 7th Fleet ships. The hardware is a refrigerator-size metal device found mounted on the exterior of warships. The capabilities of the AN/SLQ-59 are one of those military secrets China is eager to obtain. There is little unclassified information about AN/SLQ-59, other than the official name and that it is part of TEWM and related to the larger AN/SLQ-32 family of sensors. It is known that AN/SLQ-32 is meant to quickly identify threats during combat and suggest countermeasures, or automatically activate them. When seconds count, AN/SLQ-32 is a vital defensive system.
Navies and air forces seek to detect new enemy electronics used in offensive weapons and defensive systems. This is where the U.S. Navy has long had an edge. Not only does the navy have a number of AGI (Auxiliary General Intelligence, or electronic reconnaissance) ships, but also specialized AGI type aircraft. How important these aircraft are to the Chinese was made clear in the late 1990s when American electronic reconnaissance aircraft were increasingly harassed when found flying off the Chinese coast, outside of Chinese territorial waters (everything 22 kilometers from the coast) but close enough to detect the electronic emissions of Chinese electronic systems. The Chinese were trying to drive off these aircraft and that led to a collision between a U.S. Navy EP-3 electronic reconnaissance aircraft and a Chinese fighter in April 2001. The navy surveillance plane made an emergency landing in southern China after suffering damage during a collision with one of two Chinese J-8 fighters. The US Pacific Command said its EP-3 plane issued a mayday signal and was able to land at an airbase on Hainan Island after the incident over the South China Sea. The four-engine propeller plane was on a routine mission in international airspace at the time of the collision. The incident took place 140 kilometers from Hainan, in water deemed international by everyone except China, which now claims the entire South China Sea as sovereign Chinese territory.
The 2001 incident was a minor collision that appeared to be an accident. The Chinese had not forced the plane down. The two aircraft literally bumped into each other. There were no casualties among the 24 EP-3 crew members. The U.S. eventually got the EP-3 and its crew back. But only after the Chinese literally disassembled the aircraft and carefully scrutinized everything. It turned out that the crew had not been able to destroy all classified equipment and data on the aircraft before it landed and the crew was forced off the aircraft and taken into custody. The EP-3 damaged by the collision and the pilots found they could land, or possibly crash land, on Hainan (the nearest land) or try for a crash landing at sea. The latter option put the crew at more risk and provided less time to go through the protocols for destroying equipment and data. The damage to the EP-3 was unknown at that point but it was serious and the pilots realized they could not “circle the airfield” to give the crew more time to destroy secret gear. So the Chinese found out a lot (how much was never made public) about what aircraft like the EP-3 collect and this appeared to shock the Chinese into making changes in how they developed and tested electronic equipment.
Since the EP-3 incident run-ins between Chinese and US aircraft have continued along the Chinese coast. There have been no more aircraft lost or forced to make an emergency landing. The Chinese have increased the number of AGI ships. It is feared that China might eventually be able to station EP-3 type aircraft in Cuba or Venezuela but that would still not enable them to monitor U.S. Navy tests of new equipment off the west coast of North America or Hawaii, except occasionally when one of their new aircraft carriers was in the area.
At the time of the 2001 incident, China had begun developing a modern AGI ship. China now has nine Dongdiao class Type 815 AGI vessels. In a tradition stretching back to the Cold War (1948-1991), AGIs regularly show up uninvited at naval exercises held in international waters. There these ships loiter while collecting all the electronic and photographic data they can. What AGI ships cannot do is fly off the coast on short notice to monitor tests of new weapons and sensors.
While the growing number of Chinese warships visiting foreign waters appears threatening, the AGIs are not warships but in many respects are more of a threat. In the last twenty years, China has become a major user of AGIs which, during the Cold War, were mainly used by the U.S. and Russia. The Americans still have a lot of them but Russian AGIs have largely disappeared, and are now replaced by even more capable Chinese models.
In early 2018 China launched its ninth Type 815 AGI ship. This was significant in several ways, most obviously because China has built six of these ships in the previous four years and now has nine of them in service or preparing for service. With this many modern AGI ships, China is suddenly able to collect information worldwide and on a sustained basis. In less than a decade China has gone from nowhere to everywhere in offshore intelligence collection.
The Type 815s are 6,000 ton vessels that are 130 meters (418 feet) long and have a crew of about a hundred sailors plus 150 specialists and technicians. Top speed is 36 kilometers an hour and armament consists of a 37mm and two twin 25mm autocannon, which are apparently there mainly to keep minor threats away (pirates, suspicious small craft in general). There is also a landing pad and hanger for a helicopter.
These ships sport several domes protecting antennae and the ship is crammed with computers and signals processing gear. The Dongdiao class are replacing at some of older, and much less capable, AGI type ships that entered service in the 1970s. Some of these older ships have had their electronics and other information gathering gear upgraded but they are still elderly ships and expensive to maintain. Most of the AGI work is being done by the Type 815 models.
This equipment upgrading has already taken place with the Type 815, which first appeared in 1999 as something of a prototype for a new class of AGI. The second Type 815 did not appear until 2010 and it was the same ship but with obvious differences in the type and arrangement of radars, antennae and other visible sensors. Inside the ship were was much more powerful computers and electronics in general. In 2017 the sixth Type 815 was another major upgrade and was called the Type 815A in recognition of how extensive the upgrades had been since the first Type 815.
In 2014, before this spurt of Type 815 construction, China had about a dozen AGIs of varying sizes and ages. The Dongdiaos are the largest and most modern and are apparently going to replace most or all of the older AGIs. The Type 815s, like most AGIs worldwide, are mainly about electronic reconnaissance and collection. Just keeping track of the enemy's electronic devices has become a major military activity, especially since no one knows exactly how everyone’s electronic equipment will interact until there is a sustained period of use. Such use does not occur in peacetime when the EW equipment is used infrequently for training and testing. In addition, all electronic equipment has a unique electronic signature. Even equipment that is not broadcasting will appear a certain way to various sensors like radar or sonar. Thus a critical peacetime function is to determine what these signatures are. For this reason, navies and air forces devote a significant amount of their time tracking other nation’s capabilities. The best time to do this is during large scale naval exercises or the normal operation of coastal air defense and other military radars.
The growing military use of electronic sensors and communications (ESM or Electronic Support Measures) has made forces more capable, but also more vulnerable, especially if enemy AGIs spend a lot of quality time monitoring your operations.
As a counter to ESM scrutiny and vulnerability (to detection in combat) equipment can be disguised where possible. Signals can be varied in some circumstances. For equipment that is detected by shape and composition, like aircraft and ships, their shape and substance can be designed to minimize detection. This is the essence of the stealth technology that the United States is applying to a number of vehicles, especially aircraft. Small ships, aircraft, helicopters and vehicles loaded with sensors do most of the collecting. Low flying satellites are useful for catching signals deep inside a nation’s territory. UAVs and unmanned surface and subsurface vessels are used also, plus robotic sensors that are left on the ground or sea bottom. The collection involves more than sensors. Recording devices, foreign language interpreters and signal processing equipment also come into play.
Computers are increasingly crucial in sifting through the ocean of data swept up. Huge libraries of signals are collected, analyzed and boiled down to manageable amounts of data which friendly troops and weapons can use. ESM has been so successful that one entire class of sensors, active sensors, has become endangered. Active sensors detect things by broadcasting a signal. When this signal bounces off something, the sensor detects the bounce back and knows something is out there. This is the basis of radar, which broadcasts microwaves, and sonar, which broadcasts sound. Because of the signal being broadcast, a passive sensor can detect it.
Passive sensors just listen. Because active sensor signals must reach an object with sufficient energy to bounce something back, a vehicle carrying a passive sensor will detect a vehicle carrying an active sensor first. This is what happens you use a radar detector in your car to detect police speed trap radars. You usually have time to slow down before your illegal speed is detected by the police radar. As users of these devices well know, there is constant competition to come up with better radars and countermeasures. Passive sensors are the hot item in research and development these days and for obvious reasons. Passive sensors are nearly impossible to detect. Passive sensors can also pick a wide variety of signals. Infrared sensors can detect heat, including something as faint as body heat or the hot skin of an approaching jet aircraft.
AGI ships have lots of collecting to do and, when it comes to AGI vessels, having too many of them is never enough. For the Chinese it is different because of the growing number of Chinese claims on maritime territory. For Australia a visit by a Chinese AGI more of a threat than a curiosity.
China is developing EP-3 type aircraft, which can monitor what is going on 22 kilometers from the coasts of Taiwan, South Korea, Japan and other nations in the region.