The bench test (2): Mix, match & modify

System operation is centred on the video control unit (VBC) and the (audio) bus control unit (BC). These can be viewed as two separate sub-systems, video and audio, since each has its own power supplies and its own distribution network, carrying power and data signals to the entrance stations and appropriate room stations. Each distribution network is essentially a two-wire bus; there are some connection restrictions, particularly with the video network.

A VBC will support a maximum of 150 video room stations and a BC up to 250 audio room stations so that a maximum capacity video system may be installed, with a further 100 audio room stations added. Further video expansion is possible using an additional video control unit.

When installing a smaller system (two-call to 30-call), dedicated call buttons may be fitted at the entrance stations. These are available in standard modules (9.5 x 10.5cm fascia) containing two, three or four buttons with a directory card (plate & paper) alongside each button. When a call button is pressed, a calling tone is generated at the appropriate room station for approximately 10 seconds (three rings). When a video station is called, the monitor is powered up instantly. It gives a clear picture in roughly two seconds and can be viewed before the handset is lifted so that unwanted callers can be ignored. Audio communication is established when the handset is lifted.

Each station has buttons for switching on an entrance light and operating a door release (strike); the exception to this being that when "auto-entry" is enabled and switched on, the door release operates the instant the call button is pressed. Auto-Entry can be enabled only by the installer, but is toggled on/off by the room station user pressing the entrance light switch button. On/off indication is given by the room station LED flashing. When Auto-Entry is enabled, the entrance light is no longer controlled by the enabled room station light switch.

Terminals are provided in each room station for connecting a room doorbell button. The doorbell calling tone is quite distinct from the entrance station calling tone, in order to avoid confusion. If the room station does not respond, then the calling process is timed out after approximately 2.5 minutes. For larger systems, a digital name scrolling system is recommended in order to avoid making a really big hole in the entrance lobby wall. This consists of a name scroll module having a backlit LCD display and an illuminated alpha-numeric digital keypad module.

The caller can then access a directory of residents' names and room numbers stored in the system, either by scrolling through the directory, entering the directory at any alphabetical point or by entering the room number. The display of room numbers along with the corresponding name can be withheld from the casual browsing scroller, in order to retain some privacy.

The name scroll module displays caller-friendly call progress messages, in the chosen language. It also allows access by entering a four-digit code, so that designated callers can enter without disturbing individual residents. Programming can be carried out via the keypad module or by PC with the connecting cable supplied. Download programming & alteration method is available from the Aiphone website at www.aiphone.com Installation is generally straightforward, but slowed considerably for the first time installer by the Instructions.

Construction
The entrance station is made up of standard sized modules each measuring 105mm (W) x 95mm (H) in frontal area. The number and type of modules required will depend on the installation: audio only or video, and whether name scrolling is to be used.

We looked at a video system with additional audio room stations and name scrolling, requiring a camera module, a speech module, a name scroll unit and a 10 key module (which has 12 keys). These were assembled in two steel module frames, and secured in plastic back boxes (pattresses) 200mm (H) x 110 (W) x 45 (D).

The cast alloy module front panels, with the appropriate openings and chromed buttons, clipped neatly into cast alloy frames. The frames were then hooked in place over the modules and secured at the bottom by a single tamper-resistant screw. The front panels and frames are finished in semi-matt silver which, along with the chromium-plated buttons, gives the solidly-constructed entrance station a very neat up-market appearance.

The room stations are housed in semi-matt white plastic covers with full gloss handsets, door release and light buttons for the more subtle appearance. They are each, along with the bus control units, built around a single well-supported PCB. Quality of PCB construction is up to the high standard generally seen in security equipment, giving high reliability operation.

Installation
The manufacturer recommends an installation sequence of entrance station, control units and power supplies followed by room stations and finally programming: all very logical and indeed effective.

The problem we found, as first-time installers, was getting started on the entrance station. The components are supplied, separately packed but identified only by a code. The best advice we can offer is that before attempting to open a box, mark it with the name of the contents by referring either to the invoice or the product guide. The diagrams of the modules in the Installation Manual are similarly identified only by a code, so that writing down the names by the respective diagrams will save time and avoid frustration.

There are two methods of connecting the video bus lines: either "daisy-chained" from monitor to monitor or "star" connected to a four-way bus junction unit. Both methods can be used in a system but must not be mixed on any one of the six video control unit output bus line connections. The terminating switch setting on each video room station is determined by the method used.

Provision is made for looping the audio bus lines through the four-way bus junction units and the video room stations.

When installing audio room stations, the system capacity diagrams in the product guide appear to favour a junction box (type not specified) sited near the bus control unit, which has just one pair of output terminals. The maximum number of room and entrance station loadings are also given in the system capacity diagrams. CP24 P22 The maximum recommended cable lengths depend upon the effective diameter of the cable used and are given in tabular form in the product guide and the installation instructions.

The twin cable supplied to us was stranded (24/0.2 mm – roughly equivalent to 1mm), while the connectors are designed for single cored cable; push in to connect, press button to release. Using stranded cable, the button also needs to be pressed for connecting and the cable ends tightly twisted to avoid stray cores causing shorts. The bus control units and power supply units are installed at what we assume is referred to by the manufacturer as "the distribution point". 24 volt DC is connected directly into the bus control units and to the entrance station for the name scroll unit (if installed).

Power is also needed at the entrance station for the light and door release. BC Technology supplied PSUs of a higher rating than those specified, giving a 2A DC output and a 1A AC output.

We assembled the system on the bench, paying particular attention to the bus and interconnecting wires in the entrance station and the bus wires behind the video room stations, as warned in the Installation Instructions. The system was powered up with no problems and programmed manually. It all worked as expected and we were quite impressed with the fast response time and good monitor picture quality.

   Our main criticism of the Installation Instructions is centred on the two pages at the beginning, headed System Configurations. They are full of perfectly accurate diagrams but without an intelligible word in sight.

   A five-language glossary, along with a written system overview would have eased the problem considerably. Step-by-step installation instructions are very good, with clear highlighted accompanying diagrams.

The Product Guide, which we as installers generally ignore, proved to be the time saver. It contains component recognition names, typical system layouts, system capacity and a specification.

The Digital Name Scrolling Operation Manual included programming instructions which were clear and easy to follow, as were the Room Station and System Operation manuals. All fairly straightforward after clearing the initial hurdle to reach the start of the learning curve!