MF-MOD AM/FM Modulation

The AM/FM modulation option allows generation of phase-coherent linear combinations of up to 3 oscillator frequencies. The direct measurement of (higher-order) sidebands in a variety of different modulation schemes, including amplitude modulation (AM) and frequency modulation (FM), can be conveniently set up in the LabOne® user interface.

Unlike conventional double demodulation schemes, e.g. tandem demodulation, the user will not need multiple instruments and is also not limited in modulation frequencies by the maximum available demodulation bandwidth.

EUR 1,300.00
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MF-MOD Key Features

  • Simultaneous amplitude modulation and demodulation
  • Simultaneous frequency modulation and demodulation
  • Adjustable filter settings for each frequency component
  • Sideband separation (single-sided modulation)
  • Analysis of higher-order sidebands and multiple carrier frequency

MF-MOD Upgrade and Compatibility

  • Requires the MF-MD Multi-Demodulator option
  • Field-upgradeable without hardware changes
  • Compatible with all other MF options

MF-MOD Functional Diagram

MF-MOD amplitude modulation

In AM, the amplitude of a carrier signal changes periodically. In most applications, this modulation is small and therefore subject to noise. Recovering an AM signal with a lock-in amplifier relies on its steep filters and time integration to extract the signal of interest. As the AM spectrum consists of 3 frequency components, the MF-MOD option uses 3 demodulators to demodulate all 3 frequencies simultaneously and provide best-in-class signal recovery performance. Simultaneous amplitude modulation and demodulation can be entirely controlled from the LabOne user interface of the instrument.

MF-MOD frequency modulation

In FM, the frequency of a carrier signal varies periodically. As the modulation often constitutes a small signal and is therefore prone to noise, the demodulation provided by a lock-in amplifier can be advantageous thanks to its configurable filtering. The instrument demodulates the signal of interest at several frequencies simultaneously, and the MF-MOD option adds FM demodulation at the carrier frequency and at a selectable pair of sidebands with frequencies (ωc ± n * ωm). For narrow-band operation, the peak frequency deviation and the modulation frequency must satisfy the relation ωpm << 1. Nevertheless, the HF2LI-MOD option also works at peak frequency deviations up to the limit ωpm < 2 with decreasing accuracy.

MF-MOD user benefits

  • Single-box solution for bimodal and multi-modal measurement challenges without intermediate signal conversion
  • Straightforward setup
  • Simultaneous access to X, Y, R, and Θ for up to 3 phase-coherent frequency components (not possible with tandem demodulation)
  • No limitation of the modulation frequencies by the maximum demodulation bandwidth (tandem demodulation)
  • Compatibility with the MF-PID option and an external reference to derive carrier and modulation frequency from a high-performance PLL and/or external sources
  • Ability to discriminate signals from upper and lower sidebands

MF-MOD Specifications

Amplitude and frequency modulation
ωc, fc: carrier frequency range 210 nHz to 500 kHz; 210 nHz to 5 MHz, requires MF-F5M option
ωm, fm: modulation frequency range 210 nHz to 500 kHz; 210 nHz to 5 MHz, requires MF-F5M option
ωs, fs: sideband frequency fs = m * fc ± n * fm; with fs < max ωc
Ac: amplitude of carrier signal Ac < Vrange
m,n: harmonic analysis m,n = 1 to 32
Amplitude modulation
hAM: AM modulation index hAM = Am / Ac
Am: amplitude of modulation signal Ac + Am < Vrange
Frequency modulation
hFM: FM modulation index hFM = fp / fm
ωp, fp: peak frequency deviation demodulation fp < 2 * fm
ωp, fp: peak frequency deviation modulation fp < 12'000 * fm

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