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Australian Astronomy MNRF

Australian Astronomy MNRF. Development of Monolithic Microwave Integrated Circuits (MMIC) ATCA Broadband Backend (CABB). MMIC DEVELOPMENT. AIM: Develop existing ATNF expertise in MMIC design. Important area for the SKA.

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Australian Astronomy MNRF

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  1. Australian Astronomy MNRF • Development of Monolithic Microwave Integrated Circuits (MMIC) • ATCA Broadband Backend (CABB)

  2. MMIC DEVELOPMENT • AIM: • Develop existing ATNF expertise in MMIC design. • Important area for the SKA. • Develop MMICs for use in SKA demonstrators and for new ATNF receiver systems. • TECHNOLOGIES: • InP, GaAS, SiGe, RF-CMOS.

  3. Examples • Broadband LNAs, e.g. 1-3GHz, 4-12GHz. • mm-wave LNAs. • Devices for digital and analogue data transmission. • High speed, high precision samplers/digitisers. • Integrated receiver systems.

  4. ATCA BROADBAND BACKEND • AIM: • To investigate new signal processing technologies for the SKA. • To demonstrate them in a new backend for the ATCA • Increase the maximum bandwidth from 128MHz to 2GHz. • Operational in late 2006. • GAINS: • Enhanced frequency coverage - up by factor 16 • Continuum sensitivity up by at least a factor of 4 • Increased flexibility - simultaneous spectral lines

  5. COMPARISON: At l = 3mm CURRENTFUTURE Max. velocity coverage: 300 Km/s 5000 Km/s Velocity resolution at max. bandwidth: 6.4 Km/s 3 Km/s ( 60 chans ) ( 2000 chans )

  6. DESIGN PARAMETERS • 2 frequencies, each with 2 polarisations • 2 GHz maximum bandwidth • Full range of lower bandwidths • 2048 channels on all 4 Stokes parameters • 8 stations – ATCA + SKA Demonstrators • 4 GSample/sec, 6-bit (min.) sampler/digitisers • FX correlator architecture • Digital Filter Banks

  7. SYSTEM COMPONENTS • Data transmission • Conversion system • Sampler/digitisers • Delay system • Filter bank / correlator • Tied array • Online software

  8. SYSTEM COMPONENTS (1) • Data transmission • New single mode fibre installed. • Analogue or Digital ? • Analogue: • 4 to 12GHz band transmitted. • Digital: • ~128GBits/s from each antenna

  9. SYSTEM COMPONENTS (1) • Analogue data transmission: • Advantages: • Move all digital electronics away from antennas • reduced self-generated RFI • Simplifies antenna electronics • Cheaper • Difficulties: • Maintaining dynamic range

  10. SYSTEM COMPONENTS (2) • Sampler/digitisers • Fixed 4GS/s sample rate • Effective number of bits >6 • Increased dynamic range • Correlator efficiency ~100%

  11. SYSTEM COMPONENTS (3) • Conversion system - LO/IF • Single 2GHz analogue • anti-aliasing filter • Interference suppression filters • where necessary • Fixed LOs, Sampler Clocks

  12. SYSTEM COMPONENTS (4) • Correlator • Look forward to SKA • FX architecture • Using polyphase digital filterbanks

  13. FIR FFT FIR FFT FringeRotators Correlators DMUX Filterbank CORRELATOR ARCHITECTURE • Polyphase Filterbank 32k taps per filter Clocked in at 4GHz DFB clocked at 2MHz (M=2048) • Field Programmable Gate Arrays (FPGA) Commercial devices Endlessly configurable

  14. MODES • Standard • Zoom • n*Zoom • n*Zoom^m

  15. DFB Development • Development of demonstrator polyphase filterbank spectrometers • Current best performance: • 256MHz BW - 1024 frequency channels • Using ATNF 4GS/s, 2-bit samplers AND Lower sample rate 8-bit samplers • Installed at Mopra in May 2004

  16. Conventional Channelisation

  17. Filterbank Channelisation

  18. CORRELATOR TYPES • XF • For each baseline ( ~N2 ) : • Form cross correlation function • Fourier transform to form spectrum • FX • For each signal ( ~N ) : • Form spectrum • For each baseline ( ~N2 ) : • Multiply corresponding frequencies

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