the signal recovery model 7265 uses the latest digital signal processing (dsp) technology to extend the operating capabilities of the lock-in amplifier to provide the researcher with a central measurement and control facility. at the same time due consideration has been given to the needs of users wishing only to make a simple measurement quickly and easily.
operating over a frequency range of 1 mhz to 250 khz, the model 7265 offers full-scale voltage sensitivities down to 2 nv and current sensitivities to 2 fa. the unit has a choice of operating modes, signal recovery or vector voltmeter, for optimum measurement accuracy under different conditions, and the use of dsp techniques ensures exceptional performance.

the instrument performs all of the normal measurements of a dual phase lock-in amplifier, measuring the in-phase and quadrature components, vector magnitude, phase angle and noise of the input signal.

several new modes of operation are also include giving the user greater levels of versatility than ever before, for example;

virtual reference
under suitable conditions, this mode allows measurements to be made in the absence of a reference signal

dual reference
in this mode the instrument can make simultaneous measurements on two signals at different reference frequencies, which is ideal, for example, for use with our model 198a,   model 197 or model 651-1 dual-beam choppers in source compensated optical experiments.

spectral display
this allows the spectrum of the signals present at the input to be calculated and displayed, which can help when choosing the reference frequency

transient recorder
in this mode, the auxiliary adc inputs can be used as a 40 ksa/s (25 祍/point) transient recorder, with the captured transient being displayed graphically

frequency response
this built-in experiment allows the internal oscillator frequency to be swept between preset frequencies, whilst simultaneously measuring the input signal magnitude and phase. the mode is ideal for determining the frequency and phase response of external networks

harmonic analysis
most lock-in amplifiers will measure signals at the applied reference frequency or its second harmonic. in the 7265, operation is possible at harmonics up the 65,536th, and in dual harmonic mode, simultaneous measurements can be taken on two harmonics

three auxiliary adc inputs, one of which is a special integrating convertor, four dac outputs and eight output logic lines are provided. these can be used to record the magnitude of external signals associated with the experiment, such as temperature or pressure, or to generate voltages to control or switch other equipment. information from the adcs together with the lock-in amplifier"s output data can be stored in the 32k point buffer memory, and even displayed graphically on screen.

the model 7265 is extremely easy to use. all instrument controls are adjusted using soft-touch, front panel push-buttons, with the present settings and measured outputs being displayed on the centrally located, cold fluorescent backlit dot-matrix lcd. a particularly convenient new feature is the pop-up keypad which is used when setting controls that need adjusting to a large number of significant figures.

control se-lection and adjustment is aided by the logical structure of on-screen menus and sub-menus, supported by a series of context-sensitive help screens. a number of built-in automatic functions are also provided to simplify instrument operation.

external control of the unit is via either the rs232 or gpib interfaces, using simple mnemonic-type ascii commands. a second rs232 port allows up to sixteen 7265 or compatible instruments to be operated from a single rs232 computer port by connecting them in a "daisy-chain" configuration.

software support is available in the form of a labview driver supporting all instrument functions, and the acquire? lock-in amplifier applications software. the driver and a demonstration version of the software, demoacquire, are available for download from this site.