p3ter

Hi, It's my first post here! I have been trying to find information about powering multiple cameras with a single PSU, and I've noticed a number of internet shops selling pigtail style 12v connectors, allowing you to power multiple cameras with a single power supply, but the the shops that sell these never give any information about how/when they can be used, or what the limitations are. e.g. sctltd.co.uk / acatalog / WiringPower . html From my (poor) understanding of electronics, I know that a simple device like this will not isolate one camera from another, and in the end, you will create one big circuit. This may not be a problem if all cameras are the same make & model, and have the same length cable runs, but what happens if the devices have different current demands, or even simply different lengths or gauges of wire? I have 4 cameras connected to a Geovision GV250 card, all the cameras have IR LED's, and all draw between 280ma to 500ma. The longest cable run is 25 meters, but I also have a 15m, 10m, and 2.5m cable run. Only 2 of the cameras are the same make/model, but even these are on different length cable runs. I have tried simply wiring a number of cameras to a single regulated switched PSU (12V 2A), but with limited success. (well I suppose the fact that I have not ruined any cameras yet is pretty successfull!) It seems like some of the cameras work together, but others either 'switch each other off' (plugging in one causes the image to black out on the other), or sometimes trip the PSU. I have had more success with cheaper (regulated, but not switched) PSU's, but it just doesnt feel like a safe solution... I have tested all connections, and I don't have any wiring faults, so it seems like it is the interaction between the different cameras that causes the problems. I have seen the big tin cubpoards you can get (Pelco and others) which of course would solve my problem, but I already have more than enough power supplies I have also seen that there are devices that simply act as regulators, with some kind of physical or thermal fuses. OK I've rambled on enough... maybe to try ask some specific questions..! * when can simple pigtail style cables for mutiple cameras safely be used? * what do you think is happening when I plug in one camera and the other camera switches off? * what are the basic requirements for safely running mutiple camers off one PSU? * is there a simple & cheap device I can buy that will allow me to run multiple cameras safely off a single 'run if the mill' switched 'laptop brick' style PSU? Thanks for any pointers! Peter

Take a look at Proximis Girder - its possible to create custom solutions for IR/Wireless remote controls, it does this by intercepting the signal "what button was pressed?" at the PC, and doing pretty much whatever you like with the event.

Microsofts RDP is actually one of the best things they have developed in years , and significantly outperforms VNC in terms of low lag (input) fast response speed & screen refresh speed, compared to a relatively small amount of bandwidth used. However a security measure in RDP makes it hard to use in a number of situations that are relevant to CCTV applications. Logging into an RDP session 'logs off' the local user (even if you are logging in with the same username/password), and means that their computer screen, and any external secondary displays or TV-out connections, are all replaced with the Windows Logon screensaver. Logging out of the remote RDP session does not log the local user back in, therefore the display cannot be used to monitor live video until a local user physically logs back in again. Another issue with RDP is the way that it uses the remote session's PC screen resolution - this makes it hard to use software that has a fixed size GUI (like Geovision), and can risk that you end up saving a window layout or window position that is not appropriate for the local session's screen resolution. (when the local user logs on, a window might open off-screen for example, or the fixed size gui may not be the correct one for the local screen size, resulting in a need to restart the computer) VNC (and its variants) in contrast just shows a copy of the local display, and allow the advantage of 'leaving everything as is' when you log in & out, while also allowing the local user to see exactly what you are doing. I use both RDP & VNC, depending on what I need to do. If privacy of the remote session is important, or I have a low bandwidth connection, or I need to do a lot of configuration/install type work, I will use RDP. But If I want to preserve the local screen and allow the remote user to see what I'm doing, I'll use VNC. But if using RDP, I always end my session by rebooting the local machine, so that all the local settings are restored. I usually use Microsofts "TweakUI" utility to configure PC's so that they always automatically log on a limited rights user (not a local adminitrator) at boot time, and set the Geovision software to load automatically on reboot.

Do a Google search on "KVM over IP" (with the quotes) - you will see lots of devices that do what you are describing. I believe some of them actually use the VNC protocol, which means you can use your familiar "VNC Viewer" client. The main difference is that VNC, RDP, etc are software solutions running on the currently running operating system, wheras these devices connect externally to the Keyboard, Video & Mouse ports, digitize this information & and send it over an IP network. Most remote desktop solutions are not intended to deliver video at full frame rate, so these solutions should really only be considered for controlling the computer, not for viewing security cameras live (unless you have a REALLY low frame rate...) One of the situations this type of device might be useful is where a crashed server needs a callout just to perform the reboot, but for 9/10 problems there is a simpler/cheaper alternative. A watchdog device (Google cleware "usb watchdog" for one example) that plugs in via the USB port, and presses the servers reset button if a 'keep alive' signal is not received.