title: Low-noise correlation measurements based on software-defined-radio receivers and cooled microwave amplifiers.
abstract: We present a microwave correlation measurement system based on two low-cost USB-connected software defined radio dongles modified to operate as coherent receivers by using a common local oscillator. Existing software is used to obtain I/Q samples from both dongles simultaneously at a software tunable frequency. To achieve low noise, we introduce an easy low-noise solution for cryogenic amplification at 600-900 MHz based on single discrete HEMT with 21 dB gain and 7 K noise temperature. In addition, we discuss the quantization effects in a digital correlation measurement and determination of optimal integration time by applying Allan deviation analysis.
authors.affiliation: Low Temperature Laboratory, Department of Applied Physics, Aalto University School of Science, P.O. Box 15100, FI-00076 Aalto, Finland.
authors.forename: Teemu
authors.initials: T
authors.lastname: Nieminen
authors.affiliation: Low Temperature Laboratory, Department of Applied Physics, Aalto University School of Science, P.O. Box 15100, FI-00076 Aalto, Finland.
authors.forename: Pasi
authors.initials: P
authors.lastname: Lähteenmäki
authors.affiliation: Low Temperature Laboratory, Department of Applied Physics, Aalto University School of Science, P.O. Box 15100, FI-00076 Aalto, Finland.
authors.forename: Zhenbing
authors.initials: Z
authors.lastname: Tan
authors.affiliation: Low Temperature Laboratory, Department of Applied Physics, Aalto University School of Science, P.O. Box 15100, FI-00076 Aalto, Finland.
authors.forename: Daniel
authors.initials: D
authors.lastname: Cox
authors.affiliation: Low Temperature Laboratory, Department of Applied Physics, Aalto University School of Science, P.O. Box 15100, FI-00076 Aalto, Finland.
authors.forename: Pertti J
authors.initials: PJ
authors.lastname: Hakonen