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Remote surveillance systems that send real-time motion video down an ordinary telephone line brings to mind Dr Johnson’s famous remark upon seeing a performing dog walking on its hind legs: ‘The wonder is not that it does it so well, but that it does it at all’…


Sending video by phone is indeed a remarkable feat when you consider that the public telephone network was never meant to handle anything more complicated than low quality analogue audio signals, yet it can be done, and done well as the Remote Surveillance Module marketed by 8x8 Ltd proves most convincingly.


The system is based around a pair of identical transceiver units, designated RSM-1600. One is installed at the remote site, the other at the monitoring station. The basic system has three video inputs and audio channel but it can be quickly and easily upgraded to handle up to 8 cameras (and one sound channel) plus a set of associated alarm inputs using an optional RSM-700 Video/Alarm Expander module.


The technology owes much to developments spun off from the Internet and digital video compression systems. The latter uses a variety of technique to reduces the amount of data in a colour video image, one of which is to compare the colour, detail and movement information contained in successive frames and only process those parts of the picture that actually change.


Simplicity of installation, set-up and use has been given a high priority by the designers. The RSM-1600 is a plain-looking black box, just a little larger than a VHS cassette. The cases measure 41 x 24 x 124mm and weigh in at just over 1kg. On the front there is a pair of phono sockets (for one of the three audio and video inputs), and two indicator LEDs showing power on and status. On the back there is a pair of RJ-11 telephone sockets, four phono sockets for video and audio in/out, two mini DIN sockets labelled accessory and adaptor, a DC power socket and an on-off switch. The accessory socket is used to connect the RSM-1600 to an RSM-700 expander module or a third camera and an optional RF modulator uses the adaptor socket, so the unit can be connected to an ordinary TV, instead of a monitor. An external mains adaptor supplies power.


The RSM-700 is very slightly larger than the transceiver unit (50 x 27 x 120mm) and has a featureless front panel, apart from the manufacturer’s logo. On the back of the unit there is a bank of 8 panel-mounted BNC sockets, one for each of the camera inputs; next to the lower bank of sockets there is a set of mini DIP switches for setting video termination. There’s a captive lead with a mini DIN plug for connecting to an RSM-1600 and a min DIN socket labelled ‘Accessory’; the instructions indicate this is for ‘future expansion’. To the right of that there are two phono sockets for line level audio and microphone inputs and on the right side of the panel there are two banks of screw terminals for alarm inputs and outputs.


The cases are fabricated from steel the cosmetics are smart but discrete; they look and feel very solid. General build quality is very good indeed. Inside the RSM-1600 modules there are two very busy-looking glass-fibre PCBs containing mostly surface mount components. The larger main board is responsible for the video and audio processing, the smaller daughter board is a modem with a relatively modest maximum transmission speed of 33.3kbps. The modem is sits on top of the main board and the two are physically connected together by multi-way connectors. All of the input and output plugs and sockets are mounted on the PCBs, which bodes well for strength and reliability.



Installation is very simple indeed and once the various video audio and telephone connections have been made at both ends the system is ready to run. Incidentally, only one monitor/TV is only needed (at the monitor station) though one can be fitted to the remote transmitter if required. By now you may be wondering how the system is controlled in the absence of any obvious controls or displays. It’s actually very easy, the designers have cleverly used the numeric keypad on the phone connected to the monitoring unit, to access on-screen displays, menus and control functions on both units.


In a basic 1, 2 or 3 camera set-up the first step is to dial the remote station from the monitor unit’s handset. The remote RSM-1600 picks up the line after four rings and sends a system ready signal consisting of three short bleeps, the user responds by pressing the hash (#) button on the phone’s keypad, followed by digit 1 and the two units go through a handshake routine, followed by an exchange of data. The monitor screen displays a progress bar, confirming connection speeds and that data is being received. After about 20 seconds or so the inset screen – which has been blank until this point – changes and an image from camera number 1 appears on the screen. The operator can then change to a menu screen and switch between any of the connected cameras. Alternatively the user can enter the base-station and remote units set-up menus for additional configuration and status reports.


Options include changing the quality of the image by increasing or reducing the image refresh rate and altering the size of the displayed image. Additional facilities include taking still video snapshots, remote control of a pan/tilt zoom mount and there’s provision to set a security code, to prevent unauthorised access


When an RSM-700 is connected to the remote unit additional menu items appear allowing camera sequence and dwell times to be set, configure alarm and audio inputs and name alarmed cameras. To speed up operation and bypass the menus there are a number of so-called ‘hot-keys’, which select camera inputs or various operating modes with just one or two key presses.


The RSM-700 also includes an option for the remote unit to auto dial the monitoring station upon receipt of an alarm. The monitoring station can be set to auto-answer the incoming call and display the relevant image. The monitor unit has a relay-controlled output to activate a local alarm.



The system is capable of operating at four resolution settings, which trade picture size and quality against refresh rate. The best quality is 704 x 576 pixels at 0.5 sec frames per second. The alternatives are 352 x 288 pixels at 1-3 fps, 176 x 144 pixels at 5-11 fps and 128 x 96 pixels at 15fps. Picture quality on the 704 x 576 pixel setting is very good indeed – depending of course on the camera, scene lighting, movement etc. -- the image is clear enough to be shown full screen and for an operator to make out fine detail, like car number plates and facial features. Colour fidelity is reasonable though needless to say so much digital processing involves a fair number of compromises when it comes to rendering subtle shades and graduations in brightness and contrast.  At the high quality/big picture setting the image is basically a series of updated stills, which makes it difficult to analyse movement but at lower resolutions -- with faster updates -- motion is relatively smooth (albeit with greatly reduced detail). The snapshot facility is okay, as far as it goes, but the system has no internal memory so it is important to have the monitoring unit connected to a recording device or video printer as the still image is lost as soon as the operating mode changes or the connection to the remote site is cut.


Sound quality is fairly good considering. It’s comparable with normal analogue telephone connections, certainly good enough for speech and incidental sounds.



The most impressive feature is how easy the system is to set up and use, once you get used to the menu structure and the strictures of a telephone keypad. Image quality on the highest setting is very good indeed, the picture is not as sharp as a hard-wired camera, but in the right conditions there’s really not a lot in it. There’s definitely enough detail in an image for it to be used for serious surveillance applications. However, the key point is that the RSM-1600 makes remote site surveillance and protection a practical and affordable option for commercial and possibly even domestic installations. It’s also worth pointing out that the system will work on any PSTN connection, so in theory the remote site could be anywhere – including overseas – with access to a telephone line. Just the job for keeping watch on that holiday cottage in the Algarve?



Design and design features                      ****

Circuitry and components                *****

Ease of installation and wiring            *****

Range and variety of functions            ****

Accompanying instructions              *****                        

Technical advice and backup            ??    

Value for money                         ??                        



ã R. Maybury 2000 2312



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