RESOURCES

Warranty

COMPANY

ACCESSORIES

ALARM,

What is a CCTV Balun?

The term "balun" is short for "Balance-Unbalance". It’s typically (but not always) a transformer where one side is connected to a signal and a ground (such as coax), and the other side has both conductors floating relative to ground, with our signal between them. For correct operation one always needs a balun at each end of the wire.

Why Balance?

From the drawing, one can see that a balanced signal has two matched conductors. They are matched because their paths to ground are identical, both at DC and at high frequencies. Any interference that couples into one conductor will cause it to move in voltage. But with Unshielded Twisted Pair (UTP) wire, the interference couples into the other conductor too. Since both conductors move, it’s important that the devices at the end of the wire have absolutely identical paths to ground, and that the circuit receive only the voltage DIFFERENCE between the conductors, while ignoring their ‘common’ voltage to ground.

The ability to reject this ‘common’ signal, while receiving the ‘differential’ signal is the basis of any balun (or active differential amplifier.) Again, a balun is required at each end of the wire.

All of these circuits perform this function, but always in a less than perfect way. The closer we come to perfect balance, the better we can reject interference.

There is a measurement for how good the balance is. It’s called Common-Mode Rejection Ratio (CMRR). On the balanced side of the balun, one puts a zero amplitude differential signal on the two wires (they’re shorted together), plus a large amplitude common signal (big voltage relative to ground). Now we measure the small voltage on the unbalanced (coax) side. Under ideally balanced conditions, the coax voltage should be zero. To the extent that there’s imbalance, a small error voltage will appear. We define CMRR as the ratio of this error signal (Vdm) to the amplitude of the common (interfering) signal (Vcm):

Easy to use and install

UTP is lighter, smaller in diameter and more flexible than coaxial cable. It is easier to install and particularly easier for moves, changes and extensions. 

                                     COAXIAL VS CAT5/UTP

	Coaxial Cable		UTP Cable
Distance	Cost (USD)*	Quality**	Cost (USD)*	Quality **
33ft(10m)	$5	Excellent	$1.5	Excellent
165ft(50m)	$24	Very Good	$7	Excellent
330ft(100m)	$44	Good	$12	Excellent
1000ft(300m)	$130	Fair	$35	Very Good
2000ft(600m)	$260	Not Acceptable	$70	Good

Remarks:
* - Price are approximate
**- Excellent -> Very Good -> Good -> Fair-> Not Acceptable

To Extend your UTP signal up to 2.4km: ACTIVE BALUN REPEATER is require.

To Protect / Regulate your DC Power after a LONG Distance, DC Converter is require.

Now this number is usually very small, so engineers convert it to decibels to make it more manageable. [For reference, 6 dB is a doubling, 20 dB is a factor of 10, 60 dB is a factor of 1000.]

CMRR = 20 * Log (Vdm / Vcm)

60 dB of CMRR over the range of 15KHz to 5MHz. This means that a 10 volt common-mode noise will generate a 10 millivolt error in our video signal.

Note that for passive BALUN, the CMRR falls away below 15KHz, meaning that it doesn’t reject 60 Hz power-line groundloops. However, by employing our active receiver, its balance extends down to DC, and ground-loops are rejected.

Benefits of BALUN UTP CCTV Video Transmission Technology

Unshielded Twisted-Pair (UTP) Structured Premise Cabling permits many communication protocols to reside in the same wire bundle. Examples include voice, data, and CCTV video and control. Benefits of structured UTP cabling include:

• Better interference rejection than coax
• UTP is less expensive than dedicated coax or fiber
• Color-coded cabling
• Unlimited bend radius
• Physically smaller than coax
• Easiest media to install and reconfigure
• UTP is extremely easy to terminate
• In many cases, the wire is already installed

History

For at least 20 years products have been available capable of transmitting video using UTP wire. For much of that time however, UTP Balun manufacturers did little more than convert an unbalanced coax signal to a balanced signal for use on the twisted pair. Some companies added gain to extend the distance. Unfortunately, these devices provided inadequate noise immunity, no ground loop isolation, and no surge protection. The security market viewed this older technology as "last resort" until recent developed high performance UTP CC

State of the Art

BALUN developed a technique of rejecting noise and interference. This allows video signals to reside in the same wire bundle with ringing telephones, Ethernet, 24VAC, RS-422 or RS-485 data, multiple video signals, etc. Unlike coax, it can also reside in high-noise environments, such as elevator traveling cables, or near fluorescent lights, radio transmitters, motors or generators.

BALUN Compared to Coax Video

• Total interference immunity
• Most models have built-in Surge Suppression
• Active models have Ground Lifting
• Active models have built-in Distance Equalization control for crisp video at all distances
• Transmission distances up to one mile or more

BALUN Compared to Fiber

• BALUN is a lower cost solution at most distances and applications
• Simple termination and installation
• Installation tools, test equipment, and labor are less expensive

The benefits of working with BALUN

Technology: BALUN has the best cross-talk immunity in the industry. All products are UL and CUL listed for the US and Canadian markets. They are also fully CE compliant for the World Market.

Budget: Low cost compare to major Manufacturers.

Frequently Asked Questions

Wire & Wiring

What kind of wire do I need to use with BALUN?

Use Unshielded Twisted Pair, Category 2 or better, 16-24AWG, stranded or solid. Using a multi-pair wire (six pairs or more) with an overall shield is OK.

Can shielded twisted pair be used?

Some customers have successfully used shielded wire up to a few hundred feet. However, does not recommend it. Its high-frequency roll-off will severely degrade the distance performance. Use of an amplified receiver can compensate for some signal loss. Multi-pair wire (six pairs or more) can have an overall shield without degradation.

Can the wire path have splices?

Yes. You can splice the wire or use 66-blocks or 110-blocks to make connections. Video can be sent through a dozen of these connections without significant degradation.

Can I transmit more than one video signal in a multi-pair wire bundle?

Yes. some models are interference rejection. Video signals can reside in the same wire bundle as multiple video signals, ringing telephones, Ethernet, 24VAC, RS-422, RS-485, etc.

Can video signals be sent in opposite directions within the same wire bundle?

Yes, however, due to near-end crosstalk, there are distance limitations. When using Category 2 or 3 wire, do not send video in opposite directions within the same wire bundle more than 1000’. With Category 5, do not send bidirectional video more than 2000’.

Can Category 6 wire be used?

Yes. Unshielded Twisted Pair wire, Category 2 or better.

Can un-twisted wire be used?

Some customers have successfully used un-twisted wire at short distances. Does not recommend it due to its interference susceptibility.

Can I use spare pairs in an existing telephone system to transmit video using BALUN?

Yes. One of the advantages of UTP CCTV is that the wiring for video can reside along with telephone system wiring. However, be sure to use “dry copper” pairs. There should be no dial-tone, 48 volts, loading coils, bridge-taps or switching on the chosen pairs.

Can I install my UTP bundle near RF antennas, flourescent lights, motors, generators, or high voltage?

Yes. BALUN signal is highly immune to interference, allowing
it to be installed near these noise-generating sources. For life-safety and electrical code reasons, never install BALUN in the same conduit as high-voltage wiring.

Supported Signals

Do BALUN support “up the coax” pan/tilt/zoom controls?

Yes. When using passive transceivers to transmit and receive, ?up the coax? control signals can be sent with the video up to 750’.

Can BALUN transmit VGA?

Yes. The NTSC output of a VGA or SVGA scan converter can be transmitted using BALUN.

How can I send video from one camera to more than one monitor using BALUN?

There are a couple ways to accomplish this. One is to connect your video source to a distribution amplifier. This provides multiple video outputs for each input. Connect a transmitter and receiver to each wire run leading back to each monitor.

The alternate method is to send the video signal to the first monitor using a pair of transceivers. Then loop out of that monitor and use another pair of transceivers to continue on to the next monitor.

What is the supported bandwidth?

DC to 5 megahertz, clear channel

Do BALUN support broadband RF/VHF/UHF?

No. Use demodulators and modulators to convert to base band composite video.

Can I transmit satellite or cable TV using BALUN?

No. BALUN do not support the wide bandwidth cable TV signal. However, a single channel can be sent if a demodulator and modulator are used.

Can I transmit a multiplexed signal on unshielded twisted pair?

Yes. That base band composite video signal is supported.

Can BALUN RS-422 or RS-485 signals?

RS-422 or RS-485 signals are hard-wired between the P/T/Z equipment and are not transmitted or received by BALUN. The data signal may be sent on a wire pair within the same bundle as the video signal.

General

Will RF interfere with the video when using BALUN?

No. BALUN signal is highly immune to interference. BALUN signals are sent differentially. That is, the equipment is only concerned with the voltage difference between the two conductors. RF or other fields will still couple into the conductors, but will do so in each conductor equally. This Common-Mode signal is ignored by BALUN equipment, which has a 60 dB Common-Mode Rejection Ratio (CMRR).

Troubleshooting

When transmitting video between passive BALUN, the video is wavy and there is a dark bar that rolls upward on the monitor. Why?

This is the result of a ground loop. Use an amplified receiver (which has built-in ground lifting), or remove the ground at the camera end. Be sure that floating the camera conforms to local/regional and National Electrical Codes.

Why is the green light blinking on the active receiver?

This usually indicates a poor connection along the wire path.

Why is there a double image in my video?

Faint shadows of the original signal shifting to the right, or “Ghosting” occurs when there is an impedence mismatch along the wire. Verify that the monitor is terminated with 75 (not in loop-through). Check for and remove any bridge-taps (another wire pair connected to the wire run).

Why does my video look like a scrambled Cable TV signal?

This typically indicates reversed polarity.

PORT BLOCKED

PC REQUIREMENT

INSTALLATION CHARGES