FAQ
General questions- What are the advantages of transferring the video over the twisted pair cable compared to the conventional coaxial cable?
- What are the advantages of systems built using a TWIST-Concentrator?
- Can (and should be there), in terms of lightning guard, connect the FTP cable screen to the middle coder point if... ?
- What capacity of DVR do I need, to write four cameras during the week?
- How the device is connected?
- Can I connect more than one camera to UTP cable?
- Will the device work with cameras using infrared lights? Will this power be enough for hermetic case with heating?
- What future development is expected?
- Is the amplitude frequency characteristic «fine tuning» realized?
- What is the maximum length of coaxial cable and power cable is allowed between the camera and the transmitter?
- Is this «power splitting» allowed for the cameras? ( image >> )
- Is it possible to apply the scheme indicated in the figure?
What are the advantages of transferring the video over the twisted pair cable compared to the conventional coaxial cable?
The advantages are:
- twisted pair is the symmetrical transmission line, and you can avoid the need for galvanic separation and more resistant to external interference, which makes it possible to obtain a quality image, unachievable in the use of coaxial cable in the same conditions;
- the possibility of simultaneous signal transmission over multiple heterogeneous cable (with equal prices the coaxial cable and twisted-pair gains achieved through the multi in the number of times pairs in cable);
- ability to use existing twisted pairs laid earlier (for example, for computer networks).
What are the advantages of systems built using a TWIST-Concentrator?
Twist-Concentrator is designed to transmit multichannel video over symmetrical twisted pairs. Using this device during the construction of large systems offers many advantages, along with convenience and ease of installation, they are listed below:
- Power supply all 24 decoders from a single power source
- «Hot Replacement» in case of malfunctions and, if necessary, expanding the system.
- LED indication of the system, as well as controls and system tunes are located on the front panel providing the convenience of operation and aesthetic appearance.
- High density decoders installation in a shielded case.
- 19-inch standard makes it possible to establish a device in a rack with other security systems.
- Built lightning guard. Protection from induced electromagnetic high-energy pulses.
Can (and should be there), in terms of lightning guard, connect the FTP cable screen to the middle coder point if:
- the decoder screen is connected to the middle point, and Twist Concentrator is earthed?
- the decoder screen is not connected to the middle decoder point, but pointing to the large screen area of pulse interference and the presence of parasitic capacity between the screen and a twisted pair has big probability of penetration phase interference in the coder and decoder?
Vyacheslav
The screen is indeed able to reduce the induced voltage in the case of grounding him from the decoder. Therefore, the screen must be connected to the middle point of a Twist terminal boards. Earthing should be warning, not zeroing.
What capacity of DVR do I need, to write four cameras during the week?
Answers for questions about device Twist-PwA-4
How the device is connected?
The device consists of a 4-channel receiver and 4 transmitters. The receiver is installed near the recording and display devices, and each transmitter directly at the camera.
Cable pinning (wire what color where to connect) is detailed in the device passport, and also duplicated on the rear of the receiver and on the transmitter lid.
Can I connect more than one camera to UTP cable?
You can do that. One 4-pair UTP cable can transmit 2 video signals and power 2 cameras. You can use one pair for each camera for signal transmission and one pair for power transfer. Note that it reduces the maximum transmission length. Maximum transfer length would go down to 100 meters instead of 400 meters for the camera with the consumption of 0.5A. The table of lengths depending on the number of twisted pairs used for power transmission and camera consumption is shown in the passport.
Will the device work with cameras using infrared lights? Will this power be enough for hermetic case with heating?
Twist-PwA-4 provides 12V 0.5A for one channel. If the lights heated require more current, the device can not be used. Next version of the device, which will provide 1A on each channel, is prepared for release.
What future development is expected?
The first unit will be similar to the Twist-PwA-4, but with current 1A per channel. In the future it is planned to manufacture 16-channel device with a load of 1A per channel, increase the range of transfer and support for RS485 protocol to control dome cameras. This device will be able to install at 19 inch rack.
Is the amplitude frequency characteristic «fine tuning» realized?
No. Actually only step length tuning with 100 meters step is realized. «Fine tuning» hardly noticeable on the monitor at the length less than 600 meters. The absence of this control does not affect the image quality in a range of working lengths. The principles of tuning simplicity and commercial viability were at the center during the development of the device.
What is the maximum length of coaxial cable and power cable is allowed between the camera and the transmitter?
Possible length of coaxial cable depends on its quality (density of sheath), and jamming environment at the facility. Under favorable conditions, the length can reach 30-50m. Length of power cable is determined by its cross-section and the camera wattage. The voltage on the camera (with a maximum consumption) should not exceed the tolerances specified in the passport. With significant distances (> 10m) it is recommended to check the voltage voltmeter.
Is this «power splitting» allowed for the cameras?
Is it possible to apply the scheme indicated in the figure?
