Fading Simulator

Features

• Supports up to 112MHz channels
• 140MHz IF
• Insertion of Flat fading
• Selective fading:
  • 1KHz resolution
  • up to 112MHz wide channels
  • up to 43 dB notch depth
• Built-in C/N generator (optional)
• Can integrate up to four (4) independent fading RF emulator channels
• Local control using a 7’’ touch screen
• Remote control via Ethernet
• Fits in 3HU in a 19’’ rack

Fading RF Emulator

The RI 241 Fading Emulator is designed to test wireless communication systems. Typically, it is used for evaluating point to point microwave radio and satellite systems. It is the only commercially available instrument that supports up to 112 MHz wide radio channels.The RI 241 Fading Emulator can be equipped with up to four (4) independent fading channels. Each channel emulates multipath fading according to Rummler’s model which is relevant for microwave radio links. Full remote control is enabled via a standard LAN connection. A built-in C/N generator is available as option to insert noise into the radio path. The C/N generator function measures the modulated carrier power and adjust the AWGN so the wanted C/N0 ratio is obtained. The C/N generator function is implemented in the digital domain of an FPGA, which gives unprecedented accuracy of the set C/N0 ratio.

Multipath Fading Simulator

The Ranatec Fading RF Emulator is a replacement for the Agilent 11757B Multipath Fading Simulator.

Applications

Fixed radio links are frequently used for various purposes within telecommunications and broadcast networks. Usually the justification for using a radio link instead of optical fibre link relates to geography, speed of deployment and/or economics. Fixed radio links are often used to provide high capacity communication links between stations in a network supporting a different service (such as mobile communications): an application known as ‘backhaul’.

Given the criticality of the backhaul, in e g a mobile network, any given radio link needs to exhibit a very high reliability. I e, taken into account the statistical nature of the radio channel (rain fading, reflections, interferences…), every individual link needs to be properly planned, dimensioned and implemented, taking the characteristics of the actual radio link equipment, as well as the local radio environment, into account.

Due to the above, the performance characteristics in terms of immunity against channel anomalies have become a key criterion when selecting radio link equipment for a network. Modern radio link equipment contains advanced signal processing, adaptive link optimization and support for a variety of link configurations – all with the aim to secure high capacity communication with the highest possible reliability.

A consequence of the ever increasing performance and functionality of radio link equipment is that the tools for test and verification need to keep a similar development pace: A product claim that can’t be verified by proper testing has little value and, as a minimum, the characteristics and performances of the radio link equipment must be demonstrated to be compliant with the standards and recommendations of national and international organizations such as ETSI, FCC, ITU and CEPT.

• Essential verifications that must be performed, includes the analysis of the detection capability of the receiver. Typical examples of these measurements are:
• Receiver sensitivity (carrier to noise characterization)
• Receiver performance in the presence of dynamic, flat fading (adaptive modulation, fast recovery)
• Immunity against disturbing signals (co-channel and adjacent channels as well as CW)
• Immunity against Multipath Fading (signature verification)

The Ranatec RI 241 is a multichannel, high performance, fading radio channel emulator, designed to fit into any general purpose, radio link test bench. It is intended as a generic test tool, all through the product lifetime of a radio link product:

• As an efficient evaluation tool during the design phase
• As an accurate verification instrument during product qualification
• As an integer part of a streamlined factory test set-up
• As a powerful troubleshooting tool in order to reproduce in-field events

The Ranatec RI 241 can be equipped with up to 4 completely independent fading channels. Each channel can emulate multipath fading according to the Rummler’s model. A built-in C/N generator with AWGN is available as an option. The modulator concept and the fact that the main functionality is digitally implemented by means of an FPGA allows for smooth upgrade of the installed base.

The RI 241 Fading Emulator is designed to replace the obsolete Agilent 11757B Multipath Fading Simulator. In addition to terrestial radio link testing, RI 241 may also serve as a verification tool for satellite communications.