A plan is in progress, to provide a user friendly, RFI tight, screened cage, for all desktop computers, used in the surrounding buildings of the observatory, such as the Visitor's Centre, the observatory administration building, and surrounding offices, and at the observatory quarters. As desktop computers become faster, their emission levels, and spectral content, become an ever increasing concern for RFI. In order to provide some level of control on these emissions, the desktop PCs will be screened in purpose built and designed screened cages, providing at least 20-30dB of suppression of emissions, enough to make their overall emissions below the sensitivity limit of the observatory receiving systems. The cages provide filtered feed-through connections, for such items as the keyboard, mouse, & monitor, along with any serial or parallel port using a standard D-connector. Network connecitivity is made through the use of fiber feed-through connections, using media adaptors to convert Ethernet Cat 5 cable to fiber. For less permanent serial connections using the the more modern serial port USB, the cage is temporarily opened, through the front door, giving access to the USB connection at the front of the PC. Such connections are made for situations where a digital camera needs to be connected to the PC, to download images, or for when USB memory sticks are needed. For more permanent USB connections, experimentation on the use of non-filtered D-connectors are to be trialled, using USB-to-mini DIN-to-D-connectors, allowing USB serial connection through the PC RFI cage. Obviously, an un-filtered connection is going to allow a certain amount of emissions to emanate from the cables, however, the extent of these emissions is an unknown at this stage, and it's expected to not be significant.
In addition to providing in-house designed and purpose built PC RFI cages, a number of commercial screened cabinets have been used, to provide a higher level of screening. These commercial cabinets are used to screen equipment where significant emission levels are resultant, due to the nature of the equipment, eg, high speed computers, containing high speed digital clocking circuits, network related equipment, etc. These cabinets provide the level of suppression needed, to guarantee minimal emissions, and afford the ability to provide maintenance, and network, data connectivity to the outside world, through fiber feedthroughs.