Securing microwave communication
Fading emulation is used in design labs, during system verification, and in conformance testing of wireless systems. The instrument generates propagation anomalies like multipath fading, flat fading and insertion of noise into the radio path. It can be used for signature testing, and to characterize adaptive equalizers and system behavior during design and system verification.
The need to verify wireless communication systems during severe propagation conditions grows with the use of wider channels – today up to 112MHz. The sensitivity to multipath fading is further increased by the use of high-order modulation, adaptive coding, advanced packet handling schemes and high performance radio that enables longer hop lengths.
ETSI (European Telecommunications Standards Institute) has recognized that multipath conditions for modern microwave radio may be expected also above 18GHz.
ETSI also noted that:
“..It is recognized that dedicated test equipment for signature is hardly available and will likely completely disappear in future; other non-specific test setups are possible, but they could be complex, bulky ..”.
This is no longer true!
The RI 241 is a modern, easy to use instrument for propagation performance measurements including signature analyses.
 ETSI EN 302 217-2-1 V2.1.1 (2014-12), 22.214.171.124.
 ETSI EN 302 217-2-1 V2.1.1 (2014-12), 126.96.36.199.
The Ranatec RI 241 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.
- 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 channels
- Local control using a 7’’ touch screen
- Remote control via Ethernet
- Fits in 3HU in a 19’’ rack
The instrument can be used in different ways depending on the verification need. The figures below show a modem test (Figure 1), a system test with radio’s (Figure 2) and a system test when the IF-signal is not available (Figure 3).
Figure 4 shows an example of complete system test of a dual polarized microwave radio system, verifying performance in both go and return paths – in total four (4) independent radio channels in a single RI 241.
In all above cases Noise and Flat Fading can be added as needed.
The RI 241 Fading Emulator is designed to replace the obsolete Agilent 11757B.