1、 STDmSMPTE 267M-ENGL 1999 8357401 O003546 753 m SMPTE STANDARD for Television - Fault Reporting in Television Systems SMPTE 2691111-1 999 Revision of ANSI/SMPTE 269M-1994 1 Scope This standard describes a simple interface over which television equipment can report the occurrence of internal failures
2、 and faults in incoming signals. It is intended for use in all television equipment, from the simplest active devices to the most complex. The interface consists of an isolated closure which can assume one of three states: open, closed, or pulsing. These respectively signal that the reporting device
3、 is okay, has detected an internal fault, or is detecting incoming signal faults. Fault occurrence data may be collected from equip- ment complying with this standard by several means, ranging from simple “follow the lights to the trouble“ summary alarm schemes to computerized logging systems. While
4、 full specification of such systems is beyond the scope of this standard, a general outline of one possible implementation is given in annex A. 2 Normative reference The following standard contains provisions which, through reference in this text, constitute provisions of this standard. At the time
5、of publication, the edition indicated was valid. All standards are subject to revision, and parties to agreements based on this standard are encouraged to investigate the possibility of applying the most recent edition of the standard indicated below. IEC 601 69-8 (1 978-Ol), Radio Frequency Connect
6、ors - Part 8: R.F. Coaxial Connectors with Inner Diameter of Outer Conductor 6.5 mm (0.256 in) with Bayonet Lock - Characteristic Impedance 50 Ohms (Type BNC) 3 Fault states 3.1 A reporting device states: 3.1.1 Normal operation The device is currently Page 1 of 4 pages may be in one of three not det
7、ecting any internal failures and is receiving power. 3.1.2 Internal failure The device is currently detecting an internal failure or has lost power. 3.1.3 Incoming signal fault The device is not detecting any internal failures, but is currently detecting faults in incoming signal(s). 4 Interface def
8、inition 4.1 Interface The interface consists of a two-wire connection from an electrically-isolated output closure in the reporting device. The interface reports faults only at the times that they are detected. The closure may be in one of three states: 4.1.1 Open An open output signifies that the r
9、eporting device is operating correctly with valid input(. 4.1.2 Closed A closed output signifies that the reporting device has detected an internal fault or has lost power. The closure lasts only for the duration of the fault. Copyright b 1999 by THE SOCIETY OF MOTION PICTURE ANDTELEVISION ENGINEERS
10、 595 W. Hartsdale Ave., White Plains, Ni 10607 (914) 761-1100 Approved April 21,1999 STD-SfiPTE 2b9M-ENGL 1i999 = 357401 0003547 89T = SMPTE 269M-1999 4.1 -3 Pulsing 5.3 Open-state characteristics Apulsing output signifies that the reporting device has detected errors in the signal) it is receiving.
11、 The pulsing lasts only for the duration of the errored field(s). When in the open state, the leakage across the clo- sure must be less than 100 pA at any voltage from O V to 5 V DC. The closure shall be able to withstand 24 V DC in the open state without damage. 4.2 Pulsing 5.4 Closed-state charact
12、eristics In the closed state, the maximum voltage drop across Pulsing is defined as a closed pulse from 1-2 ms long occurring once per field. 5 Electrical characteristics 5.1 Output the closure shall not exceed 2 Vat 20 m. The sensing device shall not supply more than 20 mA of current to the reporti
13、ng device. The output of the reporting device is a closure, elec- trically isolated from the rest of the device. The isolat- ing mechanism shall withstand a common-mode Potential of 60 v Peak at frequencies from DC to 400 Hz. The shell of the cOmctor may be bypassed to the chassis by a small-value c
14、apacitor, if needed, to limit r radiation. mechanism. 6 Connector The chassis connector used shall be a female BNC type, as defined in IEC 60169-8. The center contact shall be connected to the positive side of the sensing 5.2 Output closure The output chure must be in the closed state when power is
15、removed from the device (see annex A). Note - Only the mechanical dimensions are specified. Both 50- and 75-ohm connectors are available which meet these requirements. Annex A (informative) Possible implementation of a reporting scheme There are many ways to implement a fault data collection and rep
16、orting system using the interface specified in this standard. The implementation described here is one of the simplest. It is a hierarchical system and is designed to lead a technician to the faulty device by means of visual and audible signals. No provision is made for automated logging of faults;
17、however, such logging is not precluded. The scheme works as follows: All fault reporting outputs in each rack or frame are connected in parallel to a summary alarm repeater, which consists of a power supply, an optoisolator circuit, and an alarm lamp and driver, as shown in figure A.l. The outputs o
18、f the repeaters are connected in parallel to an identical repeater at the end of the rack row. These in turn are connected to another repeater at the entrance to the rack area, and so forth, until all alarms are summed at a staffed monitoring point. Audible alarms may also be used where desired. Whe
19、n an alarm occurs, the technician simply follows the lights to the correct room, rack area, rack row, rack, frame, and faulty module, and either resets or replaces it as re- quired. Note that this scheme relies on the device originally reporting the fault to provide visual indication of the fault co
20、ndition. Schemes of this type have been used by telephone compa- nies for years. They are simple to design and inexpensive to implement. Although they do not provide detailed fault logging, as noted, they greatly facilitate locating failures. Page 2 of 4 pages STD-SUPTE ZbqM-ENGL 1999 m 8357401 0003
21、548 726 m SMPTE 2691111-1 999 I OUTPUT Figure A.l - Summary alarm repeater Annex B (informative) Possible implementation of the output interface The requirement to signal loss of power as a fault implies that the output must revert to the closed state when the +v power is off. Figure 8.1 shows one p
22、ossible implementation of such a circuit. FAULT i OUTPUT Figure B.l - Output interface implementation example Page 3 of 4 pages Annex C (informative) Output loss detection Normal analog video system design practice is to have all outputs of a device driven by the same active components, with the dif
23、ferent outputs isolated from each other by buil- dout resistors. With this arrangement, one can determine the condition of all outputs of the device with a high degree of confidence by monitoring only one of them. In digital television systems, the bandwidths involved make commonly-driven resistivel
24、y-isolated outputs impractical. Instead, each output is typically driven by a separate active Annex D (informative) Bibliography stage, and noise considerations frequently dictate that half the output drivers are ted from the Q output of the previous stage, while the other half are fed by the not4 o
25、utput. Given this topology, monitoring one output of a device does not indicate the health of the other outputs to the degree of confidence required. The only way to provide this level of confidence is for the device itself to monitor all outputs internally, signaling a fault if any of them fails wh
26、ile the device is receiving or generating a valid input. ANSVSMPTE 259M-1997, Television - 10-Bit 4:2:2 Com- ponent and 4fsc NTSC Composite Digital Signals - Serial Digital Interface Television SMPTE RP 165-1994, Error Detection Checkwords and Status Flags for Use in Bit-Serial Digital Interfaces for Page 4 of 4 pages
