AutoEQ supports amplitude and group delay equalization over the satellite system. When installed, it offers the ability to compensate the overall system group delay and amplitude flatness by pre-correcting the uplink carrier. This eliminates the need for external group delay/amplitude equalizers and makes possible equalization at L-Band.
A key benefit of AutoEQ is its ability to improve performance of existing links and broadcast networks where the receivers lack adaptive equalizers to correct impairments. In these scenarios, AutoEQ equalizes the amplitude and group delay characteristics of the entire uplink from the earth station through the output of the satellite transponder optimizing the most critical link components. Depending on the impairments, this may improve link performance by 2 dB or more. The AutoEQ supports all DM240XR modulation and code types, including QPSK, 8-PSK, 16-APSK, 16-QAM and 32-APSK.
Ease of Operation
Operationally, an AutoEQ card is installed in a slot at the rear of the DM240XR Modulator. The card contains a specialized demodulator that receives the carrier from the satellite and uses an algorithm to automatically determine the optimum complex coefficients that eliminate amplitude and group delay impairments. These are stored in the modulator to complete the correction process. The modulator stores 32 sets of correction parameters making it ready to correct 32 uplink / transponder combinations. This setup optimizes configurations where the modulator and AutoEQ are located within the same satellite footprint.
In networks where the transponders are cross-strapped and the receiver is in a different footprint than the modulator, another strategy is adopted. A DM240XR with AutoEQ is located at the distant end of the link and Ethernet access is used to connect the distant end to the modulator to complete the closed loop algorithm and store the coefficients.
Carriers from 10 to 45 Msps are supported by AutoEQ, permitting equalization of partial or full transponders. The automatic operation eliminates the painstaking adjustments associated with IF equalizers. In addition, AutoEQ works at 70/140 MHz or L-Band making setup and adjustment a breeze. Because the AutoEQ coefficients are stored in the modulator, it is possible to use a single AutoEQ card to set up many modulators. Simply equip all modulators with the AutoEQ software option and move the AutoEQ card to each modulator.
