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Leaflet No 15 September 2002 Radio VNG: ’s Standard Frequency and Signal Service

Introduction conducted a survey to ascertain the usage of Radio VNG is Australia’s standard frequency the service and the scientific and economic and service. For many people impact of its closure. The survey results and organisations throughout Australia have showed that there was extensive and diverse made use of the timing signals broadcast by usage of the service throughout the Radio VNG. These timing signals may be used community; usage which, by the very nature of for purposes such as surveying, geophysics its application, was difficult to quantify and . Radio VNG users include economically. seismologists, astronomers, upper atmosphere Following the closure of Radio VNG in physicists, surveyors, geophysicists studying October 1987, the Commission convened a the Earth’s magnetic field and amateur radio seminar to investigate what provisions needed operators. This service forms part of to be made for an intermediate accuracy time Australia’s technological infrastructure by service and to consider the extent to which the providing a signal of moderate accuracy provisions for high accuracy time comparisons (1 millisecond) that can be readily accessed were meeting Australia’s needs. with relatively inexpensive equipment. It is Several alternatives to Radio VNG were also used to confirm any ambiguities inherent discussed but each was found to have in more precise methods of time comparison. significant disadvantages in terms of accessibility and cost compared with Radio VNG’s time service. It was recommended by the many participants at the meeting that Radio VNG be reinstated; that the service be recognised as part of Australia’s technological infrastructure and be funded by the Federal Government. At this time no single department or authority was identified to fund the operation of Radio VNG.

Background VNG Users Consortium For approximately 23 years, Radio VNG was The VNG Users Consortium was formed to re- broadcast from Lyndhurst, Victoria. It was establish Radio VNG and to collect donations funded by Telstra (formerly Telecom from former users to dismantle, pack and Australia) and the monitoring and research transfer the transmitting equipment to a new were conducted by their research laboratories location. at Clayton, Victoria. More than $10 000 was raised and the In late 1986 the Precise Time Working Group equipment was relocated to AirServices (now the National Time Committee), under the Australia’s (formerly the Civil Aviation auspices of the Commission, learned of the Authority) International Transmitting Station impending closure of Radio VNG and in Llandilo, NSW. The Australian Surveying and Land Information Group (AUSLIG, now known as the National Mapping Division, The most recent improvements to the Radio Geoscience Australia), agreed to finance the VNG time service were the addition of a operation of Radio VNG on a partial cost talking that went to air on recovery basis from users. Initially, there were 15 January 1992, and a 1 kW 2.5 MHz both technical and licensing problems, all of transmission which began on 7 October 1992, which have since been resolved. to improve reception in the Sydney Further details of the VNG Users Consortium metropolitan region. Additional transmitters are given in Appendix I. have also been acquired to provide backup to the existing system. A digital voice The Situation announcing machine, with no moving parts replaced the less reliable tape cartridge As part of its responsibility of coordinating the machines in early 1994. national measurement system, the Commission took over the funding of Radio VNG in Further technical details of the operation of November 1992 and on 12 January 1993 Radio VNG are given in Appendix II. Details became the owner of the transmitting licence. of the binary coded decimal (BCD) time code The Commission also administers the National format which incorporates time of and the Measurement Act 1960 and the Regulations day number in the are given in empowered under it. These Regulations define Appendix III. the units of measurement used for legal Radio VNG will to cease to operate from purposes in Australia, including the units of 31 December 2002. measurement for time. Further Information Currently, the Commission funds AirServices Australia to operate and maintain Radio VNG. The following information leaflets also contain The Commission also funds CSIRO to monitor information related to this topic: the accuracy of the Radio VNG transmissions No 8 The Australian National Time System and carry out other functions related to the No 27 Daylight Saving national time system and Coordinated No 28 (UTC). No 32 Leap

2 Appendix I VNG Users Consortium

The VNG Users Consortium was formed as a As a result of protracted efforts over several subcommittee of the Precise Time Working years, Radio VNG now transmits on five Group (now the National Time Committee) of frequencies instead of the original three! Other the Commission because of users dismay at contributions by the Consortium include the closure of Radio VNG in October 1987. provision of station identification The objective of the Consortium was to re- announcements, the addition of a talking establish and maintain a national high clock, and the purchase of the first 2.5 MHz frequency standard frequency and time signal transmitter and a new AWA digital service. announcing machine. At their inaugural meeting on 25 February The Commission took over the recurrent 1988 the organisers wrote to all known funding of Radio VNG on a non-cost recovery Radio VNG users requesting contributions basis in 1992. This has taken much of the towards the cost of acquiring the Radio VNG burden off Consortium volunteers, who have plant and reinstating the service. The response always done their work unpaid in their own was heart warming. Private individuals (many time. The Commission now issues most of the of whom were not paid for the activities for QSLs, though the VNG Users Consortium also which they used Radio VNG) contributed up answers queries where appropriate. The to $100 out of their own pockets, and some Consortium still provides the voice organisations contributed up to $2000 to try to announcements and represents users interests save this national facility. This enabled the to the Commission through its National Time VNG Users Consortium to pay for the Committee. relocation of Radio VNG from Clayton in The VNG Users Consortium is eager to Victoria to what was then the Civil Aviation continue to collect financial contributions for Authority’s International Transmitting Station contingencies and to enable them to have the at Llandilo, NSW, in June 1988. means to promote Radio VNG’s importance to As a result of users being willing to contribute the Government in the that its continued money to save the service, AUSLIG (now operation again comes into question. After all, known as the National Mapping Division, Radio VNG would have been if people Geoscience Australia) agreed to meet the costs had not been prepared to dig into their own of setting up at Llandilo and to cover the pockets. Money is a powerful way of showing running costs on a partial recovery basis from that we really do care! If you would like to users. The role of the VNG Users Consortium help, or if you would like any further was to raise some of this money, to represent information on the VNG Users Consortium users interests to various Government bodies, please contact to answer queries, and to verify reception Dr Marion Leiba reports (QSLs). The Consortium also Honorary Secretary negotiated with the Department of Transport VNG Users Consortium and Communications and the Royal Australian GPO Box 1090 Navy for extra frequencies for Radio VNG, as Canberra, ACT 2601 its old ones were now in the wrong part of the Tel: (61 2) 6231 9476 (home) radio frequency spectrum.

3 Appendix II Radio VNG Technical Details

Location Voice Station Identification Announcement Radio VNG is broadcast from the AirServices Australia, International Transmitting Station, This is provided on the 2.5 MHz, 5 MHz and located at Llandilo, NSW, position 16 MHz services only using an AWA digital 33°42’52"S, 150°47’33"E. voice recorder. It is given during the 15th, 30th, 45th and 60th without Transmitters interruption to the time signal. The speech is The service employs STC double sideband, ‘notched’ to allow seconds markers to full carrier AM, HF broadcast transmitters. continue and has spectral components around The 2.5 MHz service uses a STC 4SU55A/S 1000 Hz removed to avoid erroneous operation transmitter whilst the 5 MHz, 8.638 MHz, of tuned relay time circuits. 12.984 MHz and 16 MHz services employ Morse Station Identification STC 4SU48B transmitters. This is provided on the 8.638 MHz and Frequencies, Power and Emission 12.984 MHz frequencies only. It is given Mode during the 15th, 30th, 45th and 60th minutes The transmitter frequencies, powers and without interruption to the time signals. VNG transmission modes are: is transmitted in slow morse at a frequency of 2.5 MHz 1 kW, emission mode to be approximately 400 Hz up to six per advised . Broken idents may occur at the 5 MHz 10 kW, emission mode beginning and end of the minute. 6K00B9W Reception Reports 8.638 MHz 10 kW, emission mode 3K00A1A All correspondence, including reception report 12.984 MHz 10 kW, emission mode and requests for reception reports (QSLs), 3K00A1A should be addressed to: 16 MHz: 5 kW, emission mode Radio VNG 6K00B9W National Standards Commission Note: 8.638 MHz and 12.984 MHz are PO Box 282 frequencies on loan from the Royal North Ryde, NSW 1670 Australian Navy. The reports should be sufficiently detailed to Antennae permit verification. Return postage, preferably 2.5 MHz monopole (vertical antenna) in the form of an International Reply Coupon 5 MHz Wells quadrant antenna (or US$1) would be appreciated from other 8.638 MHz delta-matched quadrant antenna than VNG Users Consortium members. with a single wire per arm Talking Clock 12.984 MHz delta-matched quadrant antenna with a single wire per arm This gives Coordinated Universal Time as 16 MHz: delta-matched quadrant antenna UTC(ATC) each minute, immediately after the with a single wire per arm minute marker. It operates on 2.5 MHz, 5 MHz and 16 MHz services only. Transmission Schedule 2.5 MHz continuous Time Delay Through Transmitters 5 MHz continuous The timing of Radio VNG time signal pips is 8.638 MHz continuous done prior to transmission. Users who wish to 12.984 MHz continuous obtain the greatest accuracy could benefit by 16 MHz: 2200–1000 UTC taking into account the delays introduced by

4 the transmitters. The time delay for the 5 MHz, The time of day information is maintained 8.638 MHz, 12.984 MHz and 16 MHz services within 100 µs of UTC(ATC) and is typically is 190 µs. The delay associated with the within 10 µs of UTC(ATC). In turn 2.5 MHz is to be advised. UTC(ATC) is within approximately 50 µs of UTC. Accuracy and Traceability Unfortunately due to effects such as The time and frequency information broadcast ionospheric jitter the accuracy of the frequency by Radio VNG is traceable to the standards information received from the Radio VNG maintained by the Telstra Research broadcasts may be degraded to around 1 part Laboratories at Clayton, Victoria. The carrier in 107. The time signal accuracy is typically of frequencies and 1 kHz tone broadcast by the order of 1 millisecond. Radio VNG are within 1 part in 1011 of Telstra’s frequency standard (24 average value). The time interval information has the same accuracy as the carrier frequencies except for intervals which are subject to routine step adjustments.

5 Appendix III Radio VNG Time Code Format

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