PAK FA, T-50: News #1

You are correct. Radar cross section (RCS) values of a complex body changes with respect to the viewer. An appropriate analogy is that you see a different part of a car as you do your 'walk-around'. The only body that has a constant RCS regardless of perspective is the sphere.


Not clutter detection but clutter rejection. I will try to understand your question and answer accordingly...

In the initial stages of radar identification (detection) of an object, EVERYTHING is detected. Then the majority of those signals are compared against a table of known signals (electrical characteristics) that we do not want to send to video integration (display). That table is called 'clutter rejection' and we can add or remove signals as we wish, even on the fly. That is called 'clutter rejection threshold'.

The few remaining signals that are above this threshold are sent to the next stage where much more complex algorithms begins to work on discrete elements of these signals. For example, if the radar is looking 'up' we know we are not looking at the ground with its features like hills, cluster of plants, moving animals, flying birds, etc...So we lower the clutter rejection threshold by removing electrical characteristics that matches 'hills, cluster of plants, moving animals, flying birds, etc...' from that table. It can be like a loop if the radar is alternating between looking 'up' or 'down'.

So if we are looking 'up' and therefore we are looking at relatively 'empty' or an electrically speaking 'calm' background, any complex body that is radiating EM signals will appear as a cluster and the cluster will look like this bit of a mess...



These complex algorithms have their own complex tables to work this cluster against. For example, we know that that the complex body known as an 'aircraft' has certain physical structures that will be common to most aircrafts out there, such as a vertical stabilator all the way to the rear of the body, two horizontal stabs at the same location, a cavity (exhaust) at the same location, and so on...If this cluster exhibit electrical characteristics that are within a certain statistical range of a table, then the radar computer will flag this cluster as a 'valid' target and send it to video integration (display).

Now we have a problem if the radar is looking 'down' meaning at the ground with its 'hills, cluster of plants, moving animals, flying birds, etc...'.

The goal of video integration is to display something that is meaningful to the 'meatbag' that is sitting in front of the display......The radar computer is essentially saying: 'What a moron this meatbag really is. I have to clear up so much crap just so the moron can understand what is in front of him.'

So if there are 'hills, cluster of plants, moving animals, flying birds, etc...' that are in the system, it can be very difficult display the complex body called 'aircraft' in a meaningful manner. So the system loop back to the first stage, cranks up the clutter rejection threshold, and process any cluster of signals that is above this threshold. Remember, this cluster of a complex body is ALWAYS there, only now that it is being surrounded by many other clusters. But because it is surrounded by other clusters, it can be very difficult to mark this cluster as an 'aircraft'.

The radar computer's thought process goes like this:

- We have a cluster of electrical signals.

- We see that the cluster is above the clutter rejection threshold.

- We see that the cluster's individual electrical characteristics matches a table labeled 'aircraft'.

- We will mark this cluster as 'aircraft' and send it to display so the meatbag can understand what the hell are we seeing.

This is why military aircrafts have this tactic of using the Earth as an electrical cover just in case they are being hunted by a radar looking down. There are no guarantees that this cover will work, but air combat history proved that the odds of survival increases when the tactic is employed in many situations.


RCS reduction methods tries to insert the cluster into the clutter rejection threshold even if the radar is looking 'up' or against relatively electrically 'calm' background. The nose-on aspect is always the lowest RCS value, but if it is above the 'calm sky' clutter background, that RCS value will be flagged. If it is below that 'calm sky' clutter background, it will not be flagged. Now add the Earth's electrical mess into the mix, then the 'stealth' aircraft is practically 'invisible'. This is why radar systems prefers to look 'up' whenever possible.

This is why 'stealth' aircrafts are such threats: They are usually automatically inserted into the lowest clutter rejection threshold by most radar systems.

If everything is detected by radar and is then processed and rejected or accepted and displayed why are some radar X band and some Ka band and some L band?

I mean if radar detects everything why are specific frequency radars used for weather radars and long range search radars and short range tracking radars?

Another question of course springs to mind... how was the signal "processed" in early radars in the middle of the last century when there were no electronic computers?

PROMISING GROWTH PATHS FOR AIRBORNE COMMUNICATIONS SYSTEMS
Military Parade 2011
Author: Alexei Komyakov, Konstantin Voytkevich
Alexei Komyakov - director general of FSUE NPP Polyot.
Konstantin Voytkevich - director for research, deputy designer general

FSUE NPP Polyot (Nizhny Novgorod) is a leading Russian developer and manufacturer of aircraft radio communications equipment and has the status of the Federal Research and Production Center. It conducts R&D, carries out full-scale production and upgrades its earlier products.

Standard radio communications systems for new Gen 4++ and 5 aircraft occupy an important role in Polyot's R&D efforts. Equipping modern combat aircraft systems with the latest electronics helps integrate them into the Air Force's information management system, which provides the crew with complete information for task accomplishment in real time.

NPP Polyot develops communications systems using the integrated modular avionics (IMA) technology. Technically, the IMA computer system is defined as a set consisting of crates that comprise a set of common modules and communicate via a unified digital network. To achieve maximum effect from implementing the IMA technology, a comprehensive approach to building an avionics suite on an aircraft is required. The crates ensure the installation of modules, their communication with each other, and heat removal. Cooperation between modules is done via a motherboard carrying power supply circuits, low-speed interfaces, high-speed serial interface circuit and a PCI bus.

The performance level of advanced communications systems is characterized by high quality of data and voice transmission, improved consumer properties, compatibility with avionics, guaranteed reliability and broad applications, practical implementation of the software-defined radio concept. All non-unified communication functions are software- rather than hardware-implemented, allowing their adaptation to future changes in requirements without costly upgrades.

The software-defined radios use modern integrated microelectronics, open architecture for operation in a wide frequency range, from 2 MHz to 6 GHz, provide data and voice transmission.

The novelty of the developed systems lies in the software implementation of the maximum possible number of required functions and the use of several basic technologies: network interfaces and the user interface, opportunities for remote booting and upgrading the whole software and the necessary code to configure turn-on of all equipment. Accessibility of all system elements providing their reconfiguration and setup on the part of the network, the use of versatile hardware platforms, allowing software implementation of the most diverse functions on them, as well as software-based data security methods are of great importance.

The design of the system's equipment corresponds to the standard series defined by state standards and allows quickly building up its functionality.

All of these solutions and technologies have been implemented in NPP Polyot-developed S-111 communications system for a future Gen 5 fighter. Its main features are as follows:

- fully digital architecture allowing a significant reduction in the system weight and dimensions;

- improved communications quality and reliability;

- use of modular design makes it possible to increase the number of channels and scope of functions;

- re-programmability, i.e., the capability to store and use different algorithms without hardware modifications;

- a single internal information network reducing the number and range of interfaces used;

- software implementation of most of the functions, modulation types and emission classes together with the possibility of rapidly changing the types of operation;

- use of the Baget 2.0 standard operating system simplifying the development and improvement of the system's software modules;

- software implementation of operation modes with increased jamming immunity;

- low power consumption;

- operation via high-speed channels at up to 40 Mbps with the capability to transmit different types of information (video, data, voice).

Transceiver modules installed in the S-111 system enable operation in the HF, VHF/UHF, SHF bands: provide communication in a unified communications, navigation, identification and data transmission system and in satellite communication channels. It is possible to include radios operating in other bands in the system.

As part of a fifth-generation fighter, the S-111 system has ensured the successful accomplishment of over 60 test flights.

Versions of the system are planned to be installed on different objects operated by the Russian Ministry of Defense and foreign customers. Work is underway to adapt the system to the helicopters, long-range and military transport aircraft as well as to ground communications centers.

GarryB wrote:Will be interesting to see what changes there are to this new prototype.

I wonder when they will start testing the optical systems?

GarryB wrote:A little under powered isn't it?

To be honest that computer graphic makes it look like an F-15.