Grass Technologies amplifiers are world-renowned in the field of neurophysiology for their quality, reliability, simplicity, and serviceability. At the heart of the Comet PSG system is the AS40 Amplifier System. The amplifier is designed specifically for the PSG and EEG monitoring lab and combines the latest digital design techniques with years of amplifier design and manufacturing experience.

The AS40 is a compact 35-channel AC amplifier unit which is expandable up to 50 channels. An 8-channel DC input module and optional pulse oximeter allow for an additional 10 channels of data. This flexibility allows for wide range of physiological parameters to be monitored and recorded.

The amplifier system provides for patient safety isolation, signal conditioning (physiological signal amplification and filtering), and digitization. Communications with a host computer are accomplished using TCP/IP protocol over a 10BaseT Ethernet network or dedicated cable. A host computer, using TWin software, sets the sample rate, starts and stops the data transmission, monitors the digital data, and stores it to hard disk.

An intuitive user interface with LCD screen is present with the amplifier. From the amplifier itself, a user is able to implement such features as electrode impedance checking, amplifier calibration, and photic stimulator control. Also from the LCD display a user is able to obtain information such as connection status to the host computer, and oximetry/pulse rate information when an oximeter is in use.

Personality Modules
The flexible design of the amplifier allows different Personality Modules to be used. A patented concept*, the Personality Module communicates with the TWin software for setup and configuration of the system. The SPM Sleep Personality Module is supplied with the amplifier in Comet PSG systems.

The SPM has 18 referential EEG/PSG inputs, 1 reference input, 1 patient ground and 7 bipolar AC channels (for a total of 25 AC channels), and 2 DC inputs (integrated pulse oximeter input). An optional UPM, Universal Personality Module, is also available for extended sleep studies.

The UPM offers a combination of referential and bipolar inputs for a total of 40 AC channels. The Personality Module's design allows for an easy disconnect/reconnect to the amplifier system. Direct-connect and tethered versions of the personality modules are available.