TIA-250

Description / Abstract: This standard covers systems that transmit television signals by radio or metallic or optical cable using analog or digital techniques. These will be those systems used specifically for the transmission of television signals from a broadcasting studio to its associated television transmitter (studio to transmitter link or STL), or from a transmitting point to a receiving point via possibly one or more repeaters (terrestrial system), or from a transmitting earth station to a receiving earth station via one satellite repeater (satellite system).

It is recognized that for the transmission of television signals, it may require the tandem interconnection of several of the aforementioned systems. In these instances, consideration must be given to the cumulative effect of the various transmission degradations.

This standard applies from the point of entry to the point of exit of the television signal from the transmission system.

If equipment is to be evaluated based on this standard, the manufacturer must state the expected acceptable performance range of the transmission media over which its equipment should operate properly. Evaluations of equipment must be performed under actual or simulated operating conditions using a transmission medium having the worst case performance from the expected acceptable performance range.

The transmission system may transmit the audio and video portions of the television program on the same transmission path by any of several analog or digital multiplexing methods, or they may be transmitted separately. Only the overall performance requirements of the transmission system are specified from the pint of entry to the point of exit.

The video portion of the television program may be either a color or monochrome signal. It is recognized that a monochrome signal does not require some of the chrome related specifications given in this standard.

Definitions of short-haul, medium-haul, long-haul, satellite, and digital transmission systems are provided in section 3 of this document. These systems, along with the associated performance allocation, have been and continue to be useful in constructing interconnected system that meet the requirements of sections 6 and 7. However, building blocks such as satellite and digital transmission systems, which are less closely tied to distance parameters, are an equally valid means of achieving the end-to-end requirements of sections 6 and 7.

If this standard is used as an operational document, judgment should be initiated. Minor deviations from the standard may, therefore, be tolerated until it becomes evident that a fault condition does exist and should be corrected. However, if a perceptible picture or audio impairment, or significant deviation of test signal response is noted, the trouble should be reported at once so that corrective action can be initiated.