[time-nuts] Greetings from Australia
mark at alignedsolutions.com
Mon Jun 29 17:07:19 EDT 2015
Hi Brek. In my experience the perceived frequency difference from Doppler shift is of little or no relevance for amateur HF communications. For amateurs involved in activities such as the frequency measurement test I believe it could be at times relevant at HF. There might be a mode where Doppler shift is relevant for HF communications but I have never run across it.
In my experience when communicating at VHF and beyond it is helpful to have an accurate frequency standard when using modes such as CW, SSB, JT65 etc.
I routinely check the calibration of my 1.2 GHz (23 cm) SSB / CW setup each time I turn on the radio. I use a GPSDO as a frequency source for this. Knowing the radio is on frequency gives me one less thing to worry about when trying to make 100 mile plus contacts on this band. Even through the radio has a tcxo I still need to check the frequency each time I turn it on.
From time to time I also check the calibration of my lower frequency equipment as well. The gear with TCXO's is usually close enough in frequency that I can use it on SSB and CW without having to worry about the difference between the dial frequency and the actual frequency.
Radios that just have a plain crystal oscillator usually require me to figure out the difference between the dial frequency and the actual frequency when operating using SSB and CW at 144 MHz and higher.
When using wider band modes such as FM on 144 and 440 MHz and narrow band modes below 30 MHz I usually trust that the dial frequency on the radio will be close enough.
I hope this was of some interest.
Sent from my iPhone
> On Jun 29, 2015, at 9:33 AM, Brek Martin <bmar8190 at bigpond.net.au> 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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