ASLE - Advanced Satellite Link Emulator
Satellite emulators currently on the market target the Ka, Ku and lower band systems, where most commercial applications occur. These products cover the typical satellite link characteristics such as delay, Doppler, attenuation, AWGN and frequency errors. These parameters can be controlled by the emulators in a dynamic as well as in a static way in order to generate a realistic link model.
The Q/V band (30 to 50 GHz), the next area for commercial exploration, poses certain challenges for communication equipment. In this band, scintillations and strong attenuation dynamics require the modem designers to have appropriate algorithms in place to counteract channel impairments.
It is not feasible to use traditional counter measurements like high amplifier back off and high fade margins for these effects when the satellite system is to be operated in a cost effective way. The modern approach is to use algorithms in the digital domain which compensate for these distortions, and this is where the Q/V band link emulator plays a crucial role.
The algorithms must be verified for performance and stability specifications. One approach is to use the real channel although this has the following drawbacks:
- Few Q/V band transponders are currently available
- Difficulty in exactly repeating a test with fading situations (of crucial importance in the development phase)
- Rental costs of the transponder can be high
- Risk of imperfect spectral transmission at the prototype level, which is not desirable on a commercial satellite
The above points are compensated by a satellite link emulator. Hence the advantages of Q/V band link emulators are as follows:
- Cost-effective emulation of effects in the Q/V satellite band
- Repeatable results
- Realistic impairments
- System optimization due to minimum margins
- Stochastic models for the channel, based on ITU-R recommendations, can be emulated
- Location independent design and test (no antenna and satellite necessary, IF band = 70 MHz)
It can therefore be seen that the development of the new Q/V band satellite emulator is very important in the exploration of this new band. A cost effective implementation on the flexible GNU Radio platform is planned.
JOANNEUM RESEARCH Forschungsgesellschaft mbH, DIGITAL - Institute for Information and Communication Technologies (JR-DIG) - Michael Schmidt
JOANNEUM RESEARCH Forschungsgesellschaft mbH - DIGITAL - Institute for Information and Communication Technologies (JR-DIG)
Tel.: +43 (316) 876 - 1311