IF Electronics

The CHAMP+ IF processor system.

The CHAMP+ IF processor system has been modified to serve the new AFFTS backend. Due to its large instantaneous bandwidth with high frequency resolution just a single IF setup is required. The new IF processor consists of 14 (+2 spare) individual modules that split the 4 – 8 GHz CHAMP+ front-end signal into two 1.5 GHz wide sub-bands. Both of these sub-bands are independently amplified and down-converted to baseband (0 – 1.5 GHz). Each sub-band can be leveled remotely by SCPI protocol, and a continuum signal is provided for calibration and pointing observations. The setup allows for an overlap between the two sub-bands, so that the total bandwidth per mixer available for observations is ~2.8 GHz. The useable bandwidth at the band edges is limited by the finite response of our anti-aliasing filters (17 dB suppression at 50 MHz offset).

Frequency diagram of the CHAMP+ / AFFTS IF processor system, showing the overlapping composite IF bands. The usable IF bandwidth per pixel is ~2.8 GHz.
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