[time-nuts] Greetings from Australia

Michael Perrett mkperrett at gmail.com
Mon Jun 29 16:47:48 EDT 2015


Alex, Brek - the Doppler effect is primarily an effect of the ionosphere
moving. A 24 hour measurement of WWV on 20 Mhz shows as much as +/- 800 mHz
movement, all due to Doppler. Note that if you run the measurement over
several days at the same time of year the measured frequency will strongly
correlate with time of day. This varies both with time of day and season
as the height of the ionosphere varies. To a much lesser effect most of us
nuts see a variation due to room temperature as this effects the frequency
reference of the measurement oscillator. This effect in my shack
(uncompensated) varies about +/- 1 mHz over a 20 degree (F) temperature
change.

73, Michael / K7HIL

On Mon, Jun 29, 2015 at 12:23 PM, Alex Pummer <alex at pcscons.com> wrote:

> Not exactly Brek, as long as the position of the two stations, which are
> in contact with each other, does not vary in the time, you don't have to
> worry about Doppler effect, also if you are trying to get in touch in SSB
> mode in the 13cm  band, you rather have a precise frequency reference and
> actually the other site should have too to find each other,
> and where the Doppler  would effect your communication a special
> combination of hardware-software could provide a compensation.
> 73
> KJ6UHN
> Alex
>
>
> On 6/29/2015 9:33 AM, Brek Martin wrote:
>
>> Hi Guys :)
>> I thought I’d say thanks for the add to the group and introduce myself.
>>
>> I’m only starting to get compulsive about time and frequency.
>> My findings so far are that only the timing of the next second matters
>> because it’s too late
>> to worry about the current second by the time you have the information
>> about it.
>> It’s +10 hours here so I have to add 10 to everything, and that could
>> increment the date,
>> so then a whole calendar program is required to know what the next date
>> will be,
>> just because you need to know what date it will be on the next seconds
>> tick that occurs.
>>
>> I have a question…
>> Is the reason most amateur radio people care about accurate frequency
>> mostly about
>> operating at higher radio frequencies?
>> I imagine if a bunch of radio enthusiasts aligned their HF radios with
>> atomic standards for use
>> on those bands that doppler shift would ruin everything the additional
>> hardware put into it.
>> Cheers, Brek.
>>
>>
>>
>>
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