[time-nuts] VNG

Mon Sep 8 03:49:27 EDT 2008

Hi Jim, and all,
I was very interested in the 200mW GPS, as it could discipline a TCXO  
to give
what for time-nuts would be a low grade reference. I have a solar  
battery
system that can only support about 5 watts for ever. It would be nice  
if my
clock logging system could be backed up by it so even if the power never
came back on it would be still running.
I too recently got a rubidium oscillator. I noticed its power demands  
drop
at lower ambient temperature so I could run it at 40*C with only 7.5  
watts.
That lead into the project of a fan control that controls the  
temperature of the
base plate to 40*C. You can watch the control voltage on the crystal  
drifting
as it warms up, but with the fan control it holds constant after warm  
up.
I wonder if I am seriously upgrading the stability of the LPRO by  
temperature
controlling it.
The problem with rubidium is it will take weeks to see if it drifts  
in frequency.
cheers, Neville Michie

On 08/09/2008, at 2:59 PM, Jim Palfreyman wrote:

> Yes I was really interested in that unit many years back and made  
> enquiries.
> It all came to nothing. Hence my dive into time and frequency  
> standards to
> learn to build my own and hence becoming a time-nut.
>
> I modified Murray Greenman's GPS clock to produce VNG tones and for  
> good
> measure I built a 30 second digital voice recorder kit (from  
> Jaycar) and
> recorded the actual VNG announcement into it.
>
> Murray has also made his own VNG kit (
> http://www.qsl.net/zl1bpu/MICRO/VNGBOX/index.htm).
>
> And interestingly with my recent dive into AVR micro-controllers I've
> whipped up a VNG clock with tones. It also has a push button that when
> pressed logs the time of the button-press to the nearest  
> millsecond. Sort of
> like a stop watch but recording absolute time instead. It can  
> record up to
> 99 events. All this only took me a few hours and I built it to  
> learn about
> the AVR.
>
> I plan to drive this from a small rubidium unit (that I got from  
> ebay) and
> two 12V SLA batteries will make my own portable rubidium clock that  
> sounds
> like VNG for about $150 total!
>
> Regards,
>
> Jim
>
>
> 2008/9/8 Neville Michie <namichie at gmail.com>
>
>> There was a VNG users group that maintained the broadcast for some
>> years before the
>> transmitter broke down. The same group developed a battery powered
>> GPS receiver that
>> delivered a time service of pips and a display of current time. See
>> http://tufi.alphalink.com.au/vnguc/
>> The email address is not current.
>> I think the receiver lacked a disciplined oscillator to give standard
>> frequency output.
>> This device is very interesting as it is easy to provide a UPS for it
>> and so maintain
>> an accurate time standard that is not subject to drop out. This
>> should be useful
>> to a time-nut like me who monitors pendulum timekeepers and is
>> interested in earth tides
>> and similar phenomena.
>>
>> Does any one know of a similar device or was any of our time-nuts
>> involved with this receiver?
>> cheers,
>> Neville Michie
>>
>>
>>
>> On 08/09/2008, at 11:52 AM, Jim Palfreyman wrote:
>>
>>> Hi all,
>>>
>>> For those of you mainly in Australia and New Zealand you may
>>> remember VNG -
>>> the now long departed short wave Australian Time Signal service.
>>> These words
>>> will be familiar:
>>>
>>> "This is VNG, Lyndhurst, Victoria, Australia on 4.5, 7.5 or 12 MHz.
>>> VNG is a
>>> standard frequency and time signal service of the Australian
>>> Telecommunications Commission."
>>>
>>> and in fact if it were going now would be saying:
>>>
>>> "This is VNG, Lyndhurst, Victoria, Australia on 4.5, 7.5 or 12  
>>> MHz. A
>>> standard frequency and time signal service of the Australian
>>> Telecommunications Commission. Your attention please. In accordance
>>> with
>>> international agreement the VNG time signals will be retarded by
>>> precisely 1
>>> second on the 1st of January at zero hours Coordinated Universal
>>> Time."
>>>
>>> Now to the good bit.
>>>
>>> I have acquired a cassette tape of original recordings of these
>>> words that
>>> was used at VNG. The quality is surprisingly good. It includes 8
>>> items:
>>>
>>> 1) 13-Dec-1966 VNG maintenance announcement
>>> 2) VNG station identification announcement by Len Grice (above)
>>> that was
>>> broadcast every 15 minutes
>>> 3) January leap second announcement (above)
>>> 4) July leap second announcement
>>> 5) 1987 closure announcement by an unknown female voice
>>> 6) Final shortwave transmission at 30-Sep-1987 of VNG ending in  
>>> static
>>> 7) Full studio take of all Len Grice's announcements - including
>>> stuff ups
>>> 8) Radio Australia broadcast article on the closure of VNG dated 4-
>>> Oct-1987.
>>> (Poor quality due to poor SW reception)
>>>
>>> For safe keeping I have digitised all these using a BOSS Micro BR
>>> digital
>>> recorder and they are stored safely off site.
>>>
>>> For those of you who would like to listen to a bit of Australia's
>>> history,
>>> send me an email and I'll send you a 721KB MP3 of number 2.
>>>
>>> I'm sure it will generate a few fond memories. It sure did for me.
>>>
>>> Regards,
>>>
>>> Jim Palfreyman
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>>
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