At the end of 2013 India ordered another 15 Heron UAVs from Israel in addition to having the 25 it already has upgraded with better communications equipment and some other improvements. All this will cost $300 million and is largely in response to Chinese aggressiveness along the 4,000 kilometer border both nations share. Most of this frontier is in thinly populated mountains and hills, some of it covered with forests but a lot of it with little vegetation. The additional Herons are ideal for patrolling all this.
In late 2012 India spent $1.1 billion to upgrade the sensors on some 150 largely Israeli UAVs owned by the Indian armed forces (army, air force, and navy). For the larger UAVs this meant high resolution radar (which provides black and white video of whatever is down there, in any weather) as well as high res video cameras. These sensors tend to be housed in a gimbaled stabilized turret. That means the operator can quickly point the sensor in any direction and get a stable image. Since the cameras are digital, the zoom feature is very quick and can reveal amazing levels of detail if you have high resolution cameras.
There is a growing body of evidence making it clear that you get the best results from your UAVs by having the best sensors you can afford installed. In many cases the sensor costs as much as the UAV itself. India is not going that far, as the United States and other Western nations (including Israel) have, but they were quite close with this upgrade program. While India’s UAVs tend to be smaller than those used in Western nations, more compact, lighter, and more powerful sensors make it possible to equip smaller UAVs with very capable radars and other (video and heat) sensors.
India's largest UAV, costing about $6 million each, is the Heron 1. This aircraft has a wingspan of 16.6 meters (58.4 feet), max take-off weight of 1.2 tons, and carries a 250 kg (550 pound) payload. With a max endurance of up to 50 hours (depending on payload carried), the Herons came with day and night vidcams or a naval search radar. Cruising at about 100 kilometers an hour and flying as high as 10 kilometers (32,000 feet), the Heron is very similar in cost and performance to the United States Predator.
A smaller and older (from the 1990s) UAV is the Searcher 2. This is a 500 kg (1,100 pounds) aircraft with a 68 kg (150 pound) payload. Endurance is 18 hours and max altitude is 6,100 meters (20,000 feet). Most (about a hundred) of India’s UAVs are Searchers.
In addition to pictures there are also heat sensors that can, for example, spot terrorists trying to sneak across the border from Pakistan in Kashmir in cool or cold times of the year (which is most of the time along the Kashmiri border). These heat sensors can also be useful for maritime patrol. One of the major uses of Indian UAVs is maritime patrol.