Digital Cavity Resonance Monitor, alternative method of measuring cavity microphonics
As is well known, mechanical vibration or microphonics in a cryomodule causes the cavity resonance frequency to change at the vibration frequency. One way to measure the cavity microphonics is to drive the cavity with a Phase Locked Loop. Measurement of the instantaneous frequency or PLL error signal provides information about the cavity microphonic frequencies. Although the PLL error signal is available directly, precision frequency measurements require additional instrumentation, a Cavity Resonance Monitor (CRM). The analog version of such a device has been successfully used for several cavity tests [1]. In this paper we present a prototype of a Digital Cavity Resonance Monitor designed and built in the last year. The hardware of this instrument consists of an RF downconverter, digital quadrature demodulator and digital processor motherboard (Altera FPGA). The motherboard processes received data and computes frequency changes with a resolution of 0.2 Hz, with a 3 kHz output bandwidth.
- Research Organization:
- TJNAF (Thomas Jefferson National Accelerator Facility, Newport News, VA)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC05-84ER40150
- OSTI ID:
- 850212
- Report Number(s):
- JLAB-ACE-05-415; DOE/ER/40150-3587; TRN: US0504272
- Resource Relation:
- Conference: 12th SRF Workshop, Cornell University, July 10, 2005
- Country of Publication:
- United States
- Language:
- English
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