Profitt Company equipment for Fiber Optic links of video, audio and data transmission

By Ravil Kutuev

Review contents:

Fiber Optic technologies in broadcast sphere Profitt Company equipment for Fiber Optic links of video, audio and data transmission Axon equipment BKtel equipment for Fiber Optic networks Fiber Optics in TV and Radio broadcasting Kramer Electronics equipment for Fiber Optic lines of TV signal transmission Network Electronics equipment Snell & Wilcox Fiber Optic receivers and transmitters Equipment of Telecast Fiber Systems Company Optical node getting closer to the household Fiber Optic equipment from Vistek

With the development of digital technologies and increasing of data transmission volumes the data transmission systems based on optical communication lines are becoming more and more spread. The Profitt Company produce devices for transmitting and receiving optical signals for realizing single channel and multi channel systems for transmission of composite PAL/SECAM, component YUV/RGB, digital SDI and DVB-ASI, as well as analog and digital AES/EBU audio signals over the one single mode optical fiber. It should be noted that the single channel means single DVB-ASI stream or single video signal into which up to 16 audio channels can be encapsulated.

Multi channel transmission systems are built upon principle of transmission with Wavelength Division Multiplexing (WDM) based on its most perspective version in the conditions of city and regional network creation — the system with Coarse Wavelength Division Multiplexing (CWDM). CWDM system at relatively small price of equipment allows to provide network’s bandwidth grow with no interruptions in maintenance of already existing users. Usually the distance of city and regional networks doesn’t exceed 50…80 km which is provided by optical CWDM receivers and transmitters with no use of in-between amplifiers and re-generators.

Profit Company devices are compliant with international recommendations ITU-T G.694.2 (about wavelengths distribution) and ITU-T G.695 (about parameters). CWDM systems allow using the total optical bandwidth of fiber and organizing simultaneous operation of up to 18 channels. Optical carriers difference is 20 nm in 1270…1610 nm range.

Multi channel transmission systems from Profitt designed with the use of single channel transmitters of analog and digital video and audio signals (each transmitted on its own wavelength — CW index) with optical channels multiplexing/de-multiplexing which allows organizing redundant channels for providing transmission reliability in a case of fail of any channel (“laser — photo diode” pair).

The use of processor with Ethernet interface (PFPC-3002 for 3U frame; PFPC-3023 for 1U frame) with appropriate software lets to realize full PC based monitoring of the optical network in any point.

Signals monitored:

• Lock — presence of a signal on the input of optical transmitter/receiver;
• Audio — presence of audio signal in the input signal;
• Input Loss — SDI signal losses on optical transmitter/receiver input;
• EDH -presence of EDH code in the input signal;
• No EDH — absence of EDH code in the input signal;
• Min, Hour — display of EDH errors in the received signal during last minute or an hour;
• Start Control — start of error monitoring routing during last minute or an hour.

Besides, the equipment allows organizing redundant optical line with automated switching onto it upon fail of main line and switching back upon its recover.

Profitt Company produce devices for conversion of SDI and DVB-ASI signals to optical signals and vice versa.

Electrical-to-Optical (left) and Optical-to-Electrical signals converters

SDI and DVB-ASI to optical signal converters are equipped with input automated cable equalizer and FP-type lasers with 1310×20 nm or 1550×20 nm wavelengths. Output optical power is -3 dBm.

Optical signals to SDI and DVB-ASI converters perform re-clocking and are equipped with photo receivers based on InGaAs/InP photo diodes operating on 1100…1650 nm wavelengths. Sensitivity range is -3…-28 dBm.

Converters range is given in a table.

Profit converters
Functionality	Model	Number of slots occupied
Converter of electrical SDI/DVB-ASI signals to optical signal	POTM-3201 (POTM-3201CW)	1
Converter of optical signal to electrical SDI/DVB-ASI signals	PORC-3221	1
Converter of optical signal to electrical DVB-ASI/SDI signals	PORC-3222	1

The singe channel systems

These systems allow performing SDI and DVB-ASI signals transmission. The systems consist of transmitters (modulators) and receivers (de-modulators) of optical SDI/DVB-ASI signals.

Transmission of SDI signals with audio embedding

For embedding of audio into SDI the modules are used which allow embedding up to four channels either analog or digital audio. Analog PAL output of each module provides monitoring of the output signal. Over the monitored picture graphical four-channel audio level meter can be displayed (RMS and peak indication). Indicator’s scale is available in two versions: flattening according to EBU or quasi-analog. In a case when large number of audio channels (up to 16) required it is possible to cascade audio embedding modules over 4:2:2 bus with no expensive 4:2:2-to-SDI conversion. Output SDI signal with embedded audio is fed to SDI-to-Optical converter. At the receiving side the optical signal with embedded audio after conversion to electrical SDI signal and re-clocking is directed to audio de-embedding module. Each single de-embedding module serves for extracting of up to four audio channels. Output audio can be presented in analog or digital formats or their combinations. Analog PAL output provides monitoring of input signal. Over the monitored picture graphical four-channel audio level meter can be displayed (RMS and peak indication).

Depending on module’s modification it can be:

• Four analog balanced inputs (24-bit ADC) — AA index;
• Two analog inputs and one balanced AES/EBU input (four channels in total) — AE index;
• Two balanced AES/EBU inputs (four channels) — EE index;
• Two unbalanced AES/EBU inputs (four channels) — EEC index.

One should note that in the receiver the output signal’s format can differ from input one (analog input — AES output and vice versa).

For example: POTM-3201—12-AEEEAA is the modulator with single video input, six analog audio inputs and three balanced AES/EBU outputs. CW — transmitters/receivers for multi channel systems.

Transmitters (modulators) and receivers (de-modulators) for optical SDI video and audio
Functionality	Model	Number of slots occupied
Electrical SDI and audio signals to optical signals converter
1 video + 4 audio	POTM-3201-4-XX (POTM-3201-4CW)	2
1 video + 8 audio	POTM-3201-8-XX (POTM-3201-8CW)	3
1 video + 12 audio	POTM-3201-12-XX (POTM-3201-12CW)	4
1 video + 16 audio	POTM-3201-16-XX (POTM-3201-16CW)	5
Optical signals to electrical SDI with embedded audio signals converter
1 video + 4 audio	PORC-3221-4-XX	2
1 video + 8 audio	PORC-3221-8 -XX	3
1 video + 12 audio	PORC-3221-12-XX	4
1 video + 16 audio	PORC-3221-16-XX	5

Transmission of composite PAL/SECAM and audio signals

There are two ways of composite signals transmission available:

• With decoding and conversion to standard SDI signal and embedding of up to 16 audio channels;
• Composite signals transmitted without decoding but with use of SDI format with possibility of embedding up to 8 audio channels (analog, AES/EBU or their combination).

The nuance of transmission non-decoding composite signal is the use of standard SDI format and the possibility of passing this signal through SDI routers, amplifiers etc. A device allows embedding test lines from internal generator.

On the receiving side de-audio embedding and D-to-A conversion is performed. The advantage of this way is the use of the same modules of audio embedding and electrical-to-optical signal converters that are used for SDI signal transmission. Additional SDI input allows with no extra expenses converting this line for SDI signals transmission.

Transmitters (modulators) and receivers (de-modulators) of optical composite PAL/SECAM video signal (with no decoding) and audio
Functionality		Model	Number of slots occupied
Electrical PAL/SECAM and audio signals to optical signal converter		POTM-3203 (POTM-3203CW)	2
Electrical PAL/SECAM and audio signals to optical signal converter
	1 video + 4 audio	POTM-3203-4-XX (POTM-3203-4CW)	3
	1 video + 8 audio	POTM-3203-8-XX (POTM-3203-8CW)	4
Optical signal to electrical PAL/SECAM signal converter		PORC-3223	2
Optical signal to electrical PAL/SECAM with embedded audio signal converter
	1 video + 4 audio	PORC-3223-4-XX	3
	1 video + 8 audio	PORC-3223-8-XX	4
As XX index AA, AE, EE, EEX indexes can be used.

Component YUV/RGB and audio signals transmission

In a case of input YUV/RGB signals they converted to SDI, than audio embedded and SDI with embedded audio fed to SDI-to-optical converter. On the receiving side the reverse conversion performed followed by audio de-embedding and SDI 4:2:2 to component YUV/RGB signal conversion.

Additional possibilities

It is possible to add synchronizers, noise reducers, logo mixers and other devices from Proflex modular system which are equipped with 4:2:2 input and output. Audio output modules allow performing synchronization of output digital AES/EBU audio signal from input video or external reference AES signal.

Transmitters (modulators) and receivers (demodulators) of optical analog and digital AES/EBU audio signals

Transmitters and receivers modules allow realizing transmission (reception) the only audio signals and input format can be analog, AES/EBU or any other format combination. It should be noted that in receiver the output format can differ from input one (for instance, analog input, AES output and vice versa). Input AES frequency can be both 32 and 48 kHz but the AES output of a receiver always has 48 kHz frequency.

Transmitters and receivers of optical analog and digital AES/EBU audio signals
Functionality	Model	Number of slots occupied
Electrical-to-Optical signals converter
4 audio	POTM-3204-4-XX (CW)	2
8 audio	POTM-3204-8-XX (CW)	3
12 audio	POTM-3204-12-XX (CW)	4
16 audio	POTM-3204 -16-XX (CW)	5
Optical-to-Electrical signals converter
4 audio	PORC-3224-4-XX	2
8 audio	PORC-3224-8-XX	3
12 audio	PORC-3224-12-XX	4
16 audio	PORC-3224-16-XX	5
As XX index AA, EE, EEC indexes can be used.

Multi format transmitters/receivers

The recent developments of Profitt Company are compact POTM-3205 transmitter and PORC-3225 receiver which and both are designed for transmission both SDI and composite PAL/SECAM signals with embedding of four audio channels and one RS-232 data channel. Each of devices occupies the only slot in the Proflex modular system. On the input of transmitter one can feed either composite PAL/SECAM or SDI. Output signal is being chosen by user.

Input audio can be in analog or digital (AES/EBU) format or in their combination. Besides, Both transmitter and receiver in all modifications in terms of inputs/outputs have additional monitoring PAL output which allows the color picture to be overlaid with color four-channel audio level indicator (RMS and peak indication). Depending on laser type and its wavelength transmitters can be used in single, double and multi channels systems.

An example of organizing duplex and simplex signals transmission within 2-channel system

Transmission types
Transmitter (Input)	Receiver (Output)
PAL/SECAM (no decoding)	PAL/SECAM (equal to input system)
PAL/SECAM (with decoding)	PAL/SECAM (user’s choice), SDI
SDI	SDI, PAL/SECAM (user’s choice)

Two-channel transmission/reception systems

At the lack of transmission lines the task of organizing transmission over the single optical fiber two and more channels appears. For transmission of two channels using duplex mode as well the WDM system is used (with wavelength division). It consists of a combination of any two single channel transmitters described above with the only difference: one electrical-to-optical converter operates on 1310 nm wavelength while another converter operates on 1550 nm wavelength. Optical signals summing performed via optical multiplexer and their dividing — via optical de-multiplexers. Conversion of the optical signals to electrical ones is being done by single channel optical receivers.

Profitt Company produces PWDM-3210 optical WDM multiplexer/de-multiplexer.

The system for transmission/reception of up to 18 optical signals via single fiber optic cable (CWDM)

An example of 4-channel transmission system design

The system is based on a principle of transmitting each channel on the exact wavelength within 1270…1610 nm range with 20 nm increment. It allows transmit/receive up to 18 optical signals over single optical fiber, including signals of different formats in duplex mode. System is independent from input electrical signals formats. To form optical signals the single channel optical transmitters are used but equipped with lasers for CWDM system (DFB laser). In this case to the model’s name the CW index and numerical value of the laser’s wavelength added.

Optical signals’ summing is being done on optical multiplexer and their dividing — on the optical de-multiplexer. Conversion of optical signal to appropriate electrical signal is performed by single channel optical receivers. Each optical multiplexer/de-multiplexer has extension input allowing increasing the number of channels.

Profitt’s equipment range for this system includes optical CWDM multiplexer/de-multiplexer PCOM-3211 for 4 channels.

Automated redundancy system for optical lines

Besides of modules the Profitt Company has developed a simple and effective system of automated switching to redundant equipment upon signal disappearance or main line fail and back switching when the signal in the main line recovered.

The signal on the redundant line attenuates relatively to the main one by means of built-in attenuator to the level at which it doesn’t affect the receiver. When the main signal disappears the due to high sensitivity begins working with redundant channel. When the main channel recovered the back switching occurs.

Using the device for automated transfer and building the loop lines it is possible to create flexible redundant system.

Material provided by Profitt Company