IEC 61334

IEC 61334, known as Distribution automation using distribution line carrier systems, is a standard for low-speed reliable power line communications by electricity meters, water meters and SCADA.[1] It is also known as spread frequency-shift keying (S-FSK) and was formerly known as IEC 1334 before IEC's most recent renumbering. It is actually a series of standards describing the researched physical environment of power lines, a well-adapted physical layer, a workable low-power media access layer, and a management interface. Related standards use the physical layer (e.g. Internet Protocol over S-FSK), but not the higher layers.[2]

The physical layer synchronizes a small packet of tones to the zero-crossing of the power line's voltage. The tones are chosen by utilities, not specified in the standard. Tones are usually between 20 kHz and 100 kHz, and should be separated by at least 10 kHz to prevent cross talk. One tone is chosen for mark (i.e. a binary 1), and the other for space (i.e. 0). The standard permits each zero-crossing to convey 1, 2, 4 or 8 bits, with increased sensitivity to timing as the number of bits increases. In multiphase power lines, a separate signal might be sent on each phase to speed up the transmission.

The standard's low speed is caused by the limited number of bits per power line cycle. The speed is also limited by noise, and the local jitter of the AC line's zero crossing. The high reliability comes from its reliable timing system (i.e. zero crossing), high signal to noise ratio (frequencies are chosen to avoid common power line noise), lack of intermodulation distortion, and adaptive signal detection.

The most significant bits are sent first, unlike a conventional serial port. The data from zero crossings should be collected into 8-bit bytes. Each byte is collected into 42-byte packets. The first four bytes of each packet are a preamble to measure the channel's current condition. This is followed by 38 bytes of data, and 3 byte-times of silence.

S-FSK centers tones around the time when the AC line passes through zero voltage. In this way, the tones avoid most radio-frequency noise from arcing. (It is common for dirty insulators to arc at the highest point of the voltage, and thus generate a wide-band burst of noise.) Since tone pairs are chosen by utilities, different districts can use different tone pairs to avoid interference.

To avoid other interference, receivers can improve their signal-to-noise ratio by adapting their decoder. The silence and the preamble allow the receiver's signal processing to measure the channel's noise ratios. Depending on the signal to noise ratios, the bits can be recovered from the difference between the power of the mark and space tones, the power of the mark tones only, or the space tones only. The system should be able to adjust the receiving method on each 42-byte packet.

Bit timing is typically recovered from the boundaries of tones, much like a UART that is triggered by a start bit. Timing is roughly centered on the zero crossing with a timer from the previous zero crossing that can enable the bit detection. Practical bit timing cannot be derived from the zero crossing alone, due to local jitter and noise in the zero crossing caused by varying local loads on the grid.

The bytes from the low-layer packets are reformed into bytes for the higher layers. The higher link-layer strongly resembles HDLC, except with a novel feature that allows selected stations to retransmit messages.[3] The management interface layer provides remote control of a station's protocol layers, including diagnostics and configuration. For example, it lets a central controller read a unit's signal to noise ratios, and set the bit that enables a station to retransmit weak stations.[4][5]

The protocol layers are designed to integrate with any application layer, but the presence of a management interface suggests a design targeted to DLMS/COSEM, a widely used EU standard for the application layer of meters and SCADA. DLMS/COSEM requires a management interface.

## Contents

* 1 Spread frequency-shift keying
* 2 List of IEC 61334 parts
* 3 See also
* 4 References

## Spread frequency-shift keying

S-FSK (spread frequency-shift keying) is a modulation scheme that combines some of the advantages of classical spread-spectrum modulation (immunity against narrow-band interference) with some of the advantages of classical frequency-shift keying (FSK is low complexity). The difference between S-FSK and classical FSK is that in S-FSK, the mark frequency fm is placed far from the space frequency fs. The frequencies are placed far enough apart that frequency-selective fading and narrow-band interference only blocks one of the frequencies, so the receiver can still recover all the data from the other frequency.[6]

## List of IEC 61334 parts

* IEC TR 61334-1-1:1995 General considerations – Distribution automation system architecture
* IEC TR 61334-1-2:1997 General considerations – Guide for specification
* IEC TR 61334-1-4:1995 General considerations – Identification of data transmission parameters concerning medium and low-voltage distribution mains
* IEC 61334-3-1:1998 Mains signalling requirements – Frequency bands and output levels
* IEC 61334-3-21:1996 Mains signalling requirements – MV phase-to-phase isolated capacitive coupling device
* IEC 61334-3-22:2001 Mains signalling requirements – MV phase-to-earth and screen-to-earth intrusive coupling devices
* IEC 61334-4-1:1996 Data communication protocols – Reference model of the communication system
* IEC 61334-4-32:1996 Data communication protocols – Section 32: Data link layer – Logical link control (LLC)
* IEC 61334-4-33:1998 Data communication protocols – Data link layer – Connection oriented protocol
* IEC 61334-4-41:1996 Data communication protocols – Application protocols – Distribution line message specification
* IEC 61334-4-42:1996 Data communication protocols – Application protocols – Application layer
* IEC 61334-4-61:1998 Data communication protocols – Network layer – Connectionless protocol
* IEC 61334-4-511:2000 Data communication protocols – Systems management – CIASE protocol
* IEC 61334-4-512:2001 Data communication protocols – System management using profile 61334-5-1 – Management Information Base (MIB)
* IEC 61334-5-1:2001 Lower layer profiles – The spread frequency shift keying (S-FSK) profile
* IEC TS 61334-5-2:1998 Lower layer profiles – Frequency shift keying (FSK) profile
* IEC TS 61334-5-3:2001 Lower-layer profiles – Spread spectrum adaptive wideband (SS-AW) profile
* IEC TS 61334-5-4:2001 Lower layer profiles – Multi-carrier modulation (MCM) profile
* IEC TS 61334-5-5:2001 Lower layer profiles – Spread spectrum – fast frequency hopping (SS-FFH) profile
* IEC 61334-6:2000 A-XDR encoding rule

## See also

* Power line communication, for a survey of the topic
* Universal powerline bus, the more common shorter-ranged competitor

## References

1. ↑ IEC 61334-5-1, preface.
2. ↑ ADD GRUP, Russia
3. ↑ IEC 61334-4-1
4. ↑ IEC 61334-4-1154
5. ↑ IEC 61334-1155
6. ↑ "Power Line Carrier Modem". 2014\. p. 16

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List of International Electrotechnical Commission standards

IEC standards|

* IEC 60027
* IEC 60034
* IEC 60038
* IEC 60062
* IEC 60063
* IEC 60068
* IEC 60112
* IEC 60228
* IEC 60269
* IEC 60297
* IEC 60309
* IEC 60320
* IEC 60364
* IEC 60446
* IEC 60559
* IEC 60601
* IEC 60870
* IEC 60870-5
* IEC 60870-6
* IEC 60906-1
* IEC 60908
* IEC 60929
* IEC 60958
* AES3
* S/PDIF
* IEC 61030
* IEC 61131
* IEC 61131-3
* IEC 61158
* IEC 61162
* IEC 61334
* IEC 61346
* IEC 61355
* IEC 61360
* IEC 61400
* IEC 61499
* IEC 61508
* IEC 61511
* IEC 61850
* IEC 61851
* IEC 61883
* IEC 61960
* IEC 61968
* IEC 61970
* IEC 62014-4
* IEC 62056
* IEC 62061
* IEC 62196
* IEC 62262
* IEC 62264
* IEC 62304
* IEC 62325
* IEC 62351
* IEC 62365
* IEC 62366
* IEC 62379
* IEC 62386
* IEC 62455
* IEC 62680
* IEC 62682
* IEC 62700

ISO/IEC standards|

* ISO/IEC 646
* ISO/IEC 2022
* ISO/IEC 4909
* ISO/IEC 5218
* ISO/IEC 6429
* ISO/IEC 6523
* ISO/IEC 7810
* ISO/IEC 7811
* ISO/IEC 7812
* ISO/IEC 7813
* ISO/IEC 7816
* ISO/IEC 7942
* ISO/IEC 8613
* ISO/IEC 8632
* ISO/IEC 8652
* ISO/IEC 8859
* ISO/IEC 9126
* ISO/IEC 9293
* ISO/IEC 9592
* ISO/IEC 9593
* ISO/IEC 9899
* ISO/IEC 9945
* ISO/IEC 9995
* ISO/IEC 10021
* ISO/IEC 10116
* ISO/IEC 10165
* ISO/IEC 10179
* ISO/IEC 10646
* ISO/IEC 10967
* ISO/IEC 11172
* ISO/IEC 11179
* ISO/IEC 11404
* ISO/IEC 11544
* ISO/IEC 11801
* ISO/IEC 12207
* ISO/IEC 13250
* ISO/IEC 13346
* ISO/IEC 13522-5
* ISO/IEC 13568
* ISO/IEC 13818
* ISO/IEC 14443
* ISO/IEC 14496
* ISO/IEC 14882
* ISO/IEC 15288
* ISO/IEC 15291
* ISO/IEC 15408
* ISO/IEC 15444
* ISO/IEC 15445
* ISO/IEC 15504
* ISO/IEC 15511
* ISO/IEC 15693
* ISO/IEC 15897
* ISO/IEC 15938
* ISO/IEC 16262
* ISO/IEC 17024
* ISO/IEC 17025
* ISO/IEC 18000
* ISO/IEC 18004
* ISO/IEC 18014
* ISO/IEC 19752
* ISO/IEC 19757
* ISO/IEC 19770
* ISO/IEC 19788
* ISO/IEC 20000
* ISO/IEC 21000
* ISO/IEC 21827
* ISO/IEC 23000
* ISO/IEC 23003
* ISO/IEC 23008
* ISO/IEC 23270
* ISO/IEC 23360
* ISO/IEC 24707
* ISO/IEC 24727
* ISO/IEC 24744
* ISO/IEC 24752
* ISO/IEC 26300
* ISO/IEC 27000
* ISO/IEC 27000-series
* ISO/IEC 27002
* ISO/IEC 27040
* ISO/IEC 29119
* ISO/IEC 33001
* ISO/IEC 38500
* ISO/IEC 42010
* ISO/IEC 80000

Related|

* International Electrotechnical Commission

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