It is a Pleasure to Please Customers

Please find the quote below from a very satisfied MultiDyne customer.  Despite our explosive growth in the last few years, we still strongly value our customer relationships and do everything within our power to make every customer happy and find a solution to their difficulties. 

“I have been in this business for a little more than 30 years as an end user and a system integrator. I have never ever  had this level of customer service

and support as we been getting from Multidyne. I am personally floored, impressed and extremely grateful that we have been testing your products in

medical applications.

I thank all at Multidyne for going well over and above the call of duty.”  

Anonymous

“PS: out of 30 year this is only the second time I ever sent an email out like this. Dallas Engineers, if you are not using Multidyne, maybe you should

consider them… “

Please call the MultiDyne Team for immediate technical support and fiber optic design assistance.  Our sales engineers are available immediately to service all of your needs and requirements.

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Jim Jachetta, MS EE
Senior Vice President, Principal
MultiDyne Video & Fiber Optic Systems
www.multidyne.com

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I recently had a customer at the IBC show ask me about extending DMX lighting control signals over a MultiDyne fiber optic link.  The customer also needed to extend the 40 channels of audio over fiber.  Please see my recommendations below:

Regarding your other requirement, we have the DAM-4000 40 channels of analog audio transport.  This should me all your analog audio transport needs.  I’ve downloaded of research on the DMX lighting control format.  It is a form of RS 485 communication.  Please find the Wikipedia entry below:

http://en.wikipedia.org/wiki/DMX512-A

It appears that it is RS-485 with the baud rate of 250K.  our FMX-100 will provide RS-485 communication over one or 2 fibers.

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Increased demand for 1080p HD video requires an innovation in fibre optic video transport tools contends Jim Jachetta, senior vice president of engineering and product development, MultiDyne

By Jim Jachetta,

Jim Jachetta, SVP of Engineering

Senior Vice President of Engineering and Product Development

With the pressure to deliver content in high definition, the world of video transport is dramatically changing. From a broadcast engineer picking out equipment that will save the most time and space in a studio, to a consumer watching a soccer game at home – everyone wants more out of video. Due to this demand, we are seeing the convergence of different video transport methods across industries. High resolution standards that were previously pigeon-holed as “broadcast-only” are now becoming more widely used in every install. We are dealing with a more educated client who is interested in 1080p HD video at home and at work. Manufacturers in this space need to speed up innovation and the range of the solutions they offer in order to give users added value when it comes to HD.

In the past, designers have made a choice early on in system configuration, catering to either a pro A/V, DVI standard as the main backbone to a solution, or a 3G SMPTE broadcast standard. Now, due to customer demand, we are developing tools that have fiber optic video transport capabilities over both standards depending on the application. One such offering, the DVI-6000, which we will be showcasing at IBC 2009, offers breakthroughs in DVI and RGB over a SMPTE compliant 3G data transport.

MultiDyne has been contracted to work on a major hospitality project in Las Vegas which exemplifies the demand for solutions that address both broadcast and pro A/V requirements. Within the 67 acre city-within-a-city campus, there are retail facilities, a condo hotel, casino resort and 300,000 square feet of technologically advanced meeting and convention space. The entire campus features a fiber optic video backbone capable of 1080p 3G HD-SDI transport. The facility is capable of broadcasting live events from any of the meeting rooms or theaters to a broadcast production truck outside, and the convention center features high-tech screens, projectors and digital signage that require a DVI signal. This multi-acre campus is a banner example of how innovations in fiber optic technology must and can be used across many different applications, formats and resolutions due to the new flexibility in fiber optic gear and optical routing switchers. The MultiDyne EOS-4000 switcher is another perfect example of this − as it switches in the light domain, it is able to effortlessly transition between 3G SMPTE and DVI, allowing the user to transport any signal they require.

Fiber optic video transport solutions only continue to be more reliable than competing options. We are actively breaking the constraints of video transport over copper, allowing customers to route and send video further over a single fiber. Fiber optic solutions also allow users to “future proof” their design, with bandwidth potential for innovation over 10G. When designing a complex system using copper, all cabling has to be perfect. If a user squeaked by using copper for 3G, they will be inoperable when the “next big thing” comes along.

It is important to note that MultiDyne’s path to innovation does not end with the advancements made for video transport using the DVI-6000. We are actively designing products that will take advantage of 6G technology, leading to 10G capability. The convergence of video transport demands over several markets also continues to drive us forward. For MultiDyne, the key to not only surviving but thriving in the economic downturn has been to diversify across the broadcast, pro A/V, military and government markets. Our DVI-6000, which can be used across all of these sectors, is in line with this strategy. As IBC is one of our most important shows every year – not only to reach the European market but to meet with U.S. customers, integrators and consultants as well – we’re excited to spend time with our customers, continuing to introduce them to our products which break boundaries when it comes to DVI and 3G HD-SDI video transport.

MultiDyne (Stand 2.A54)

About MultiDyne:

For more than 30 years, MultiDyne has been a leading provider of innovative and outstanding video and fiber optic-based transport and routing systems for the broadcast, cable, satellite, production, digital cinema, pro A/V, corporate, retail, surveillance, teleconferencing, judicial arraignment, transportation, government, military, and healthcare markets. MultiDyne’s fiber optic transport and routing systems for video, SDI, 3G HD, DVB/ASI, VGA, DVI, HDMI, audio, AES, Ethernet, data, CATV, as well as the company’s other broadcast accessories are used worldwide by such industry leaders as ABC, CBS, NBC, CNN, RAI, BBC and the Department of Transportation. MultiDyne provides a seven-year warranty on its core product line. For more information, call MultiDyne at 1-877-MULTIDYNE or 1-516-671-7278, visit the company’s Web site at www.multidyne.com, or send an e-mail to sales@multidyne.com.

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Bandwidth

The optical losses and usable bandwidth of a fiberoptic system have to be taken into account. As mentioned
previously, multimode fibers have greater losses and less bandwidth compared to single mode.
Single mode has lower losses and very high bandwidth than does multimode.

Most manufacturers of multimode fiber-optic cable do not specify dispersion. They will provide a figure
of merit known as the bandwidth-length product or just bandwidth with units of MHz-kilometer. For
example, 500 MHz-km translates to a 500 MHz signal that can be transported 1 km. The product of the
required bandwidth and transmission distance cannot exceed 500:

BW × L ≤ 500

A lower bandwidth signal can be sent a longer distance.
A 100 MHz signal can be sent

L = BW – product/BW
= 500 MHz-km/100 MHz
= 5 km

Single-mode fiber typically has a dispersion specification provided by the manufacturer. The dispersion
is specified in picoseconds per kilometer per nanometer of light source spectral width or ps/km/nm. This
loosely translates to the wider the spectral bandwidth of the laser light source, the more dispersion. The analysis of dispersion of a single-mode fiber is very complex. An approximate calculation can be made with
the following formula:

BW = 0.187/(disp × SW × L),

where:

disp is the dispersion of the fiber at the operating wavelength with units seconds per nanometer per
kilometer.

SW is the spectral width (rms) of the light source in
nanometers.

L is the length of fiber cable in kilometers.

For example, with a dispersion equal to 4 ps/nm/km, spectral width of 3 nm, and a transmission length
of 20 km, then:

BW = 0.187/(4 × 10–12 s/nm/km) × (3 nm) × (20 km)
BW = 779,166,667 Hz or about 800 MHz.

If the spectral width of the laser light source is doubled to 6 nm the bandwidth will drop to about 390
MHz. This shows how significant the spectral width of the laser source is on the usable bandwidth of a fiber.
If a laser light source with a narrow optical spectral width is used, or a fiber with a lower dispersion figure,
the bandwidth and transmission distance will increase.

In single-mode fiber communications, there are two basic types of laser light sources. The first type is the
less expensive laser that uses Fabre-Perot laser diode (FP-LD) technology. The FP-LD is an inexpensive
choice for digital fiber-optic communication. With a spectral width of typically 4 nm or more, it is primarily
used for lower bandwidth or short-distance applications. The second is the distributed feedback
laser diode (DFB-LD) technology. These light sources are more expensive and are widely used for longdistance fiber-optic communications. The typical spectral width for a DFB laser is about 1 nm. When a DBF laser is used in combination with a low dispersion fiber, the transmission bandwidth and distance can be significantly higher.

Table 6-10-2 Typical Optical Fiber Loss

Table 6-10-4 Typical Fiber Optic Bandwidth

See Table 6.10-2, which shows the typical fiber-optic cable losses, and Table 6.10-4, which shows the bandwidth for different types of fiber cable.

Applications, Bandwidth of the Fiber Optic Medium, NAB Engineering Handbook, Tech Talk with Jim Jachetta bandwidth, data rate, fiber, multimode, optic, singlemode

Digital Visual Interface for DVI-I and DVI-D Fiber Transport

Digital Visual Interface (DVI)
A male DVI-D (single link) connector.
Type	Digital and analog computer video connector
Production history
Designer	Digital Display Working Group
Designed	April 1999
Produced	1999 to present
Specifications
Hot pluggable	Unknown
External	Yes
Video signal	Digital video stream. (Single) WUXGA 1920 × 1200 @ 60 Hz (Dual) WQXGA (2560 × 1600) @ 60 Hz Analog RGB video (-3 db at 400 MHz)
Data signal	R,G,B data + clock and display data channel
	Bandwidth	(Single Link) 3.96 Gbit/s (Dual Link) 7.92 Gbit/s
	Max devices	1
	Protocol	3 × Transition Minimized Differential Signaling data + clock
Pins	29
Pin out
A female DVI-I socket from the front
Pin 1	TMDS Data 2-	Digital red – (Link 1)
Pin 2	TMDS Data 2+	Digital red + (Link 1)
Pin 3	TMDS Data 2/4 shield
Pin 4	TMDS Data 4-	Digital green – (Link 2)
Pin 5	TMDS Data 4+	Digital green + (Link 2)
Pin 6	DDC clock
Pin 7	DDC data
Pin 8	Analog vertical sync
Pin 9	TMDS Data 1-	Digital green – (Link 1)
Pin 10	TMDS Data 1+	Digital green + (Link 1)
Pin 11	TMDS Data 1/3 shield
Pin 12	TMDS Data 3-	Digital blue – (Link 2)
Pin 13	TMDS Data 3+	Digital blue + (Link 2)
Pin 14	+5 V	Power for monitor when in standby
Pin 15	Ground	Return for pin 14 and analog sync
Pin 16	Hot plug detect
Pin 17	TMDS data 0-	Digital blue – (Link 1) and digital sync
Pin 18	TMDS data 0+	Digital blue + (Link 1) and digital sync
Pin 19	TMDS data 0/5 shield
Pin 20	TMDS data 5-	Digital red – (Link 2)
Pin 21	TMDS data 5+	Digital red + (Link 2)
Pin 22	TMDS clock shield
Pin 23	TMDS clock+	Digital clock + (Links 1 and 2)
Pin 24	TMDS clock-	Digital clock – (Links 1 and 2)
C1	Analog red
C2	Analog green
C3	Analog blue
C4	Analog horizontal sync
C5	Analog ground	Return for R, G and B signals

The Digital Visual Interface (DVI) is a video interface standard designed to maximize the visual quality of digital display devices such as flat panel LCD computer displays and digital projectors. It was developed by an industry consortium, the Digital Display Working Group (DDWG). It is designed for carrying uncompressed digital video data to a display. It is partially compatible with the High-Definition Multimedia Interface (HDMI) standard in digital mode (DVI-D), and VGA in analog mode (DVI-A).

Contents [hide] 1 Overview 2 Technical discussion 3 Connector 4 Specifications 4.1 Digital 4.1.1 Clock and data relationship 4.2 Analog 5 Proposed successors 6 References

Overview

The DVI interface uses a digital protocol in which the desired illumination of pixels is transmitted as binary data. When the display is driven at its native resolution, it will read each number and apply that brightness to the appropriate pixel. In this way, each pixel in the output buffer of the source device corresponds directly to one pixel in the display device, whereas with an analog signal the appearance of each pixel may be affected by its adjacent pixels as well as by electrical noise and other forms of analog distortion.

Previous standards such as the analog VGA were designed for CRT-based devices and thus did not use discrete time display addressing. As the analog source transmits each horizontal line of the image, it varies its output voltage to represent the desired brightness. In a CRT device, this is used to vary the intensity of the scanning beam as it moves across the screen.

DVI cable connectors are designed in such a way as not to allow the user to connect the cable in an incorrect position or orientation. DVI connectors are available in five models, differing in the way they handle analog or digital transfers.

In the digital transfer one or two channels are present. Video and monitor cards which are exclusively digital cannot be connected to analog, but can be connected to equipment that handles both analog and digital signals. The DVI standard also supports the Display Data Channel (DDC) and the Extended Display Identification Data (EDID), which allows computers to communicate with different monitor extensions.

“DVI-I” stands for “DVI-Integrated” and supports both digital and analog transfers, so it works with both digital and analog Visual Display Units. “DVI-D” stands for “DVI-Digital” and supports digital transfers only.

Unlike HDMI, DVI carries no audio data.

 

Technical discussion

The data format used by DVI is based on the PanelLink serial format devised by the semiconductor manufacturer Silicon Image Inc. This uses Transition Minimized Differential Signaling (TMDS). A single DVI link consists of four twisted pairs of wires (red, green, blue, and clock) to transmit 24 bits per pixel. The timing of the signal almost exactly matches that of an analog video signal. The picture is transmitted line by line with blanking intervals between each line and each frame, and without packetization. No compression is used and there is no support for only transmitting changed parts of the image. This means that the whole frame is constantly re-transmitted. The specification (see below for link) does, however, include a paragraph on “Conversion to Selective Refresh” (under 1.2.2), suggesting this feature for future devices.

With a single DVI link, the largest resolution possible at 60 Hz is 2.75 megapixels (including blanking interval). For practical purposes, this allows a maximum screen resolution at 60 Hz of 1915 x 1436 pixels (standard 4:3 ratio), 1854 x 1483 pixels (5:4 ratio) or 2098 x 1311 (widescreen 8:5 ratio). The DVI connector therefore has provision for a second link, containing another set of red, green, and blue twisted pairs. When more bandwidth is required than is possible with a single link, the second link is enabled, and alternate pixels may be transmitted on each, allowing resolutions up to 4 megapixels at 60 Hz. The DVI specification mandates a fixed single link maximum pixel clock frequency of 165 MHz, where all display modes that require less than this must use single link mode, and all those that require more must switch to dual link mode. When both links are in use, the pixel rate on each may exceed 165 MHz. The second link can also be used when more than 24 bits per pixel is required, in which case it carries the least significant bits. The data pairs carry binary data at ten times the pixel clock reference frequency, for a maximum data rate of 1.65 Gbit/s x 3 data pairs for a single DVI link.

Like modern analog VGA connectors, the DVI connector includes pins for the display data channel (DDC). DDC2 (a newer version of DDC) allows the graphics adapter to read the monitor’s extended display identification data (EDID). If a display supports both analog and digital signals in one input, each input can host a distinct EDID. If both receivers are active, analog EDID is used.

The maximum length of DVI cables is not included in the specification since it is dependent on bandwidth requirements (the resolution of the image being transmitted). In general, cable lengths up to 4.5 m (15 ft) will work for displays at resolutions of 1920 x 1200. Cable lengths up to 15 m (50 ft) can be used with displays at resolutions up to 1280 x 1024. For longer distances, the use of a DVI booster is recommended to mitigate signal degradation. DVI boosters may or may not use an external power supply.

 

Connector

Male DVI connector pins (view of plug)

Color coded female DVI connector with pin descriptions

The DVI connector usually contains pins to pass the DVI-native digital video signals. In the case of dual-link systems, additional pins are provided for the second set of data signals.

As well as digital signals, the DVI connector includes pins providing the same analog signals found on a VGA connector, allowing a VGA monitor to be connected with a simple plug adapter. This feature was included in order to make DVI universal, as it allows either type of monitor (analog or digital) to be operated from the same connector.

The DVI connector on a device is therefore given one of three names, depending on which signals it implements:

• DVI-D (digital only)
• DVI-A (analog only)
• DVI-I (integrated, digital & analog)

The connector also includes provision for a second data link for high resolution displays, though many devices do not implement this. In those that do, the connector is sometimes referred to as DVI-DL (dual link).

The long flat pin on a DVI-I connector is wider than the same pin on a DVI-D connector, so it is not possible to connect a male DVI-I to a female DVI-D by removing the 4 analog pins. It is possible, however, to connect a male DVI-D cable to a female DVI-I connector. Many flat panel LCD monitors have only the DVI-D connection so that a DVI-D male to DVI-D male cable will suffice when connecting the monitor to a computer’s DVI-I female connector.

DVI is the only widespread video standard that includes analog and digital transmission options in the same connector.^[1] Competing standards are exclusively digital: these include a system using low-voltage differential signaling (LVDS), known by its proprietary names FPD (for Flat-Panel Display) Link and FLATLINK; and its successors, the LVDS Display Interface (LDI) and OpenLDI.

Some new DVD players, TV sets (including HDTV sets) and video projectors have DVI/HDCP connectors; these are physically the same as DVI connectors but transmit an encrypted signal using the HDCP protocol for copy protection. Computers with DVI video connectors can use many DVI-equipped HDTV sets as a display; however, due to Digital Rights Management, it is not clear whether such systems will eventually be able to play protected content, as the link is not encrypted.

USB signals are not incorporated into the connector, but were earlier incorporated into the VESA Plug and Display connector used by InFocus on their projector systems, and in the Apple Display Connector, which was used by Apple Computer until 2005.

The DMS-59 connector is a way to combine two analog and two digital signals in one plug. It is commonly used when a single graphics card has two outputs.

M1-DA connectors are sometimes labeled as DVI-M1; they are used for the VESA Enhanced Video Connector and VESA Plug and Display schemes.

Specifications

Digital

• Minimum clock frequency: 25.175 MHz
• Maximum clock frequency in single link mode: Capped at 165 MHz (up to 3.96 Gbit/s)
• Maximum clock frequency in dual link mode: Limited only by cable quality (up to 7.92 Gbit/s)
• Pixels per clock cycle: 1 (single link) or 2 (dual link)
• Bits per pixel: 24 (single and dual link) or 48 (dual link only)

• Example display modes (single link):
  • HDTV (1920 × 1080) @ 60 Hz with CVT-RB blanking (139 MHz)
  • UXGA (1600 × 1200) @ 60 Hz with GTF blanking (161 MHz)
  • WUXGA (1920 × 1200) @ 60 Hz with CVT-RB blanking (154 MHz)
  • SXGA (1280 × 1024) @ 85 Hz with GTF blanking (159 MHz)
  • WXGA+ (1440 x 900) @ 60 Hz (107 MHz)
  • WQUXGA (3840 × 2400) @ 17 Hz (164 MHz)

• Example display modes (dual link):
  • QXGA (2048 × 1536) @ 75 Hz with GTF blanking (2 × 170 MHz)
  • HDTV (1920 × 1080) @ 85 Hz with GTF blanking (2 × 126 MHz)
  • WQXGA (2560 × 1600) @ 60 Hz with GTF blanking (2 × 174 MHz) (30-inch (762 mm) Apple, Dell, Gateway, HP, NEC, Quinux, and Samsung LCDs)
  • WQXGA (2560 × 1600) @ 60 Hz with CVT-RB blanking (2 × 135 MHz) (30-inch (762 mm) Apple, Dell, Gateway, HP, NEC, Quinux, and Samsung LCDs)
  • WQUXGA (3840 × 2400) @ 33 Hz with GTF blanking (2 × 159 MHz)

GTF (Generalized Timing Formula) is a VESA standard which can easily be calculated with the Linux gtf utility.

CVT-RB (Coordinated Video Timing-Reduced Blanking) is a VESA standard which offers reduced horizontal and vertical blanking for non-CRT based displays.^[2]

Clock and data relationship

The DVI data channel operates at a bit-rate multiple of 10 times the frequency of the clock signal. In other words, for every DVI clock there are 10 bits provided on each of the three data channels. The data is encoded using a standard 8b/10b encoding to provide a minimum transition density in which there are no more than five consecutive bits of the same value, which is necessary to provide reference edges for clock/data recovery circuits. As indicated in version 1.0 of the specification, the clock rate is the same as the pixel rate plus framing overhead, while there are usually 24 bits per pixel. For example, a (640 × 480) @ 60 Hz display has a pixel rate of 18.4 MHz (plus blanking overhead) so this is the minimum needed clock. But the data is actually (640 × 480) @ 60 Hz × 24 bits per pixel which is 442 Mbit/s, or 147 Mbit/s per channel. Include 8B10B overhead and you need a 184 Mbit/s data stream on each of the three data channels.

Since the data is switching at 10 times the clock rate, a receiver must recover the faster bit clock from the data lines itself (using a PLL or DLL, for instance) in a process known as clock/data recovery. The DVI clock is effectively a 1/10th frequency reference clock that is useful for the clock/data recovery circuitry to synchronize to the bitstream. DVI provides a reference clock while other serial data interfaces such as PCI Express and SATA do not because the bit rate carried by the DVI interface may vary across a wide frequency range depending on the video format being rendered. Serial interfaces that do not explicitly carry the reference clock are typically defined to run at a specific known frequency or several derivative frequencies that are related by whole number multiples (for example 2.5 Gbit/s and 5.0 Gbit/s for successive generations of PCI Express and 1.5 Gbit/s and 3.0 Gbit/s for successive generations of SATA), so in these cases a fixed frequency reference clock can be generated locally at the receiver that performs the clock/data recovery.

Analog

• RGB bandwidth: 400 MHz at -3 dB

Proposed successors

IEEE 1394 is proposed by High Definition Audio-Video Network Alliance (HANA Alliance) for all cabling needs, including video, over CoAx and/or 1394 cable as a combined data stream.

High-Definition Multimedia Interface (HDMI), a forward-compatible standard, that also includes digital audio transmission.

Unified Display Interface (UDI) was proposed by Intel to replace both DVI and HDMI, but was deprecated in favor of DisplayPort.

DisplayPort is a license-free standard proposed by VESA to succeed DVI, which also has DRM capabilities.

References

Standards, Tech Talk with Jim Jachetta Component video fiber, Composite video over fiber, connector, digital visual interface, DVI, DVI connector standard, dvi fiber link, dvi fiber optic, dvi fiber optic transport, dvi over fiber, DVI standard, DVI-6000, dvi-d, dvi-i, DVI6000, RGB -- HV over fiber, rgb over fiber, S-video over fiber, Standards, vga over fiber, Video over fiber

Depending on the application, the wavelength and can be very important.  In Multimode applications the most common wavelength is 850 nano-meters.  For high speed applications a VCSEL or Vertical-Cavity Surface-Emitting Laser is used due to it’s low cost and high speed. In Singlemode the most common wavelength is 1310 nano-meters.  Typically a Fabre Perot laser is used for applications under 15 KM.  For longer distances of up to 80 KM a 1550nm DFB or Distributed Feedback laser is used.  Over long distances, dispersion or the spreading of the laser light becomes a factor.  A DFB laser typically has a tighter optical spectrum and higher optical power so distances of over 80 KM can be reached.

Since DFB lasers have a tighter spectrum and are much more stable over temperature, they are ideal for CWDM optical multiplexing.  Up to 18 DFB lasers in varying wavelengths from 1271 nano-meters up to 1611 nano-meters can be multiplexed with a 20 nano-meter spacing on one fiber.  Due to the tight spectrum and temperature stability, the lasers maintain there assigned wavelength and do not bleed into one another.

Tech Talk with Jim Jachetta 1310nm, 1550nm, 850nm, DFB, Distributed Feedback laser, Fabre Perot laser, fiber, VCSEL, Vertical-Cavity Surface-Emitting Laser

Written by Jim Jachetta, senior vice president of engineering and product development at MultiDyne.

Common application we address is the transport of cable television signals over Singlemode fiber. There are several key items that need to be remembered when implementing a cable TV fiber optic system.

1. A RF cable TV fiber optic transport system requires angle polished SC type connectors. This type of connector is typically green in color. If fiber optic cables are connected to the CTV-2000 units that are not angle polished, the fiber optic equipment could be damaged. If you’re fiber optic infrastructure does not include SC-APC or angle polished connectors, please ask your MultiDyne sales engineer to include angle polished fiber optic patch cords.
2. The final factor is the input RF signal level delivered to the CTV-2000 fiber optic transmitter. The RF input port is a standard 75 Ohm F Type connector. The RF input range is 15 to 25 dBmV. An input RF level exceeding 25 dBmV may damage the internal laser. The optimum input RF level is 20 dBm V. An RF power meter can be used to measure the ideal RF input level. The CTV-2000 fiber optic transmitter has some external adjustments, but under most circumstances the standard automatic mode is required. Please see the user’s manual for some of these manual settings.
3. Cable TV signals can be transported over Singlemode fiber only.  A Multimode fiber does not have the bandwidth over distance capability to transport a 870 MHz signal. Theoretically a Singlemode fiber has close to infinite bandwidth making it ideal for the transport of broadband RF cable TV signals.
4. The CTV-2000 fiber optic receiver requires a specific optical input signal level. The ideal optical level seen on the optical input of the cable TV fiber optic receiver is between -3 dBm and -8 dBm. Ideally we would like to see the optical input level at or close to -5 dBm. We recommend the installer utilize an optical power meter to measure the optical power delivered to the CTV-2000 fiber optic receiver. If an optical power meter is not available, we will discuss how to approximately adjust the optical power.When the cable TV fiber optic system is designed, with the aid of one of our sales engineers, we try to calculate the required optical power for the transport distance. We take into account any splitters or taps in the fiber optic infrastructure to calculate the required optical power. For example, a system may contain one CTV-2000 transmitter and up to 32 CTV-2000 receiver units. This would describe a system with a cable TV head-end feeding 32 residential homes.We typically design the system to have a little bit too much power, say around -3 dBm’s, and then we use a variable optical attenuator to get the power in the -5 dBm sweet spot. The easiest way to measure the optical power is with an optical light meter. If the system is designed and planned out carefully, an optical light meter may not be needed. Ideally we want the optical signal slightly higher than the required -5 dBm and then we adjust the variable attenuator to get the signal as close to -5 dBm’s as possible. The video signal will look noisy if the signal is both too powerful and too weak. This fact makes the system difficult to diagnose without an optical light meter. If we assume the optical signal is too strong or powerful, we should see an improvement in the signal as you begin to slowly attenuate the optical signal. When you reach the ideal point of about -5 dBm the cable TV video signal should look its best.

FAQ, Tech Talk with Jim Jachetta broadband fiber link, cable television, cable TV over fiber, CATV, catv fiber link, CATV fiber optic link, CATV over fiber, ctv-2000, CTV2000

Written by Jim Jachetta, senior vice president of engineering and product development at MultiDyne.

Ideally one should always use single mode fiber optic transport equipment with single mode fiber and multimode fiber optic transport equipment with multimode fiber. Several of MultiDyne’s newer products such as the HD-1500 are fiber mode agnostic or support both multimode and single mode fiber.

MultiDyne uses proprietary techniques in our fiber optic optical assemblies to give the capability of supporting both multimode and single mode fiber optic cable for most of our product line.  This includes the HD-1500 family for HD SDI transport, and the DTV-235 SDI fiber optic transport solutions.

FAQ, Tech Talk with Jim Jachetta DTV-235, fiber, HD-1500, multimode, optic, singlemode

Written by Jim Jachetta, senior vice president of engineering and product development at MultiDyne.

Your Digital Facility: 3 Gb/s HD Fiber Optic Transport presented at the Government Video Technology Expo 2008 by Jim Jachetta, MS EE, Sr. V. P. of Engineering & Product Development for MultiDyne Video & Fiber Optic Systems

Your Digital Facility: 3 Gb/s HD Fiber Optic Transport

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A typical Multimode fiber optic receiver will detect 850 nm. Any wavelength outside of 850 nm will not be detected. This concludes that a Multimode optical receiver has a limited optical spectrum.

A typical Singlemode fiber optic receiver will detect any wavelength from approximately 1200 nm to 1611 nm.  Therefore a generic or standard Singlemode fiber optic receiver can receive any CWDM optical signals.  An optical receiver can only detect one optical wavelength at a time. Therefore, a CWDM demultiplexer is required before any fiber optic receiver to single out each individual wavelength and map it to the proper fiber optic receiver.

A perfect application diagram can be found on page 2 of the attached document by clicking here.  You can see in the drawing how the CWDM wavelengths can travel in both directions over the fiber and how a fiber optic multiplexer and demultiplexer is required on each side of the fiber optic transport system.

FAQ, Tech Talk with Jim Jachetta