[OZAPRS] HF frequency drift reports ...?

Ray Wells vk2tv at exemail.com.au
Thu Jun 30 18:35:26 EST 2011


All,

I believe my HF rig has done a dummy spit with regard to frequency. I've 
not logged anything since Sunday - been too busy to do daily mheard checks.

Overall this concern over frequency accuracy is nothing but hot air. As 
someone who has used HF packet for near 14 years (mostly as a BBS), all 
I can say is that for most of the time the frequency accuracy of the 
average synthesised amateur rig is more than accurate enough to achieve 
excellent results.

Whilst the benefits of an expensive modem that tracks frequency cannot 
be denied, such a unit is not necessary for good HF packet performance.

Historically I have used a waterfall display to "net" my radio and that 
method returns excellent results. Like others on this forum I seriously 
doubt the frequency that's being used by VK3MY - I have always observed 
it to be lower than other stations by about 40Hz. I net to the average 
and, despite VK3MY being about 40Hz low I logged 2100 packets from him 
in seven days. So much for the 10Hz frequency accuracy requirement 
suggested in this forum. I've found that +/- 20Hz is good enough and, if 
signals are clean, up to 50Hz error will work.

If I get a chance I'll switch from the FT747 back to the TS430 over the 
weekend.

Ray vk2tv


On 30/06/11 14:01, Gerard Hill wrote:
> Hi Terry,
>
> I would not be too concerned. Frequency reports in the list do not seem
> to expire, so they'll stay there until reset. I think the list was reset
> or is not being transmitted at the moment because the beacon has stopped.
>
> Sending the report is a good idea - thanks VK6UZ! Its an automated
> system though so you need to do your own verification. For example, I am
> sure that VK2TV-4 is not 143 Hz low. Other entries in the list are, as
> far as I can tell, reasonably accurate with a slight tendency to report
> too low a frequency.
>
> Oh and Dave, I miss VNG too. Used to use 7.5 MHz reference a lot.
>
> Cheers ... Gerard, VK2IO
>
> On 30/06/2011 1:23 PM, Terry Neumann wrote:
>>
>> It doesn't take a lot to confuse me these days. OK I'll admit it. I am
>> confused by the list of stations Mike has copied below.
>>
>> I've checked for myself and that's more or less what the site is
>> delivering in real time at this moment.
>>
>> My station is one of those listed with today's date. It hasn't been on
>> HF APRS since I returned from our Flinders Ranges trip over a couple of
>> weeks ago:
>>
>> http://aprs.fi/?call=vk5atn-15&mt=m&z=11&timerange=86400
>> <http://aprs.fi/?call=vk5atn-15&mt=m&z=11&timerange=86400> gives the
>> true picture. It's in the shed with the HF rig off and the 20 metre whip
>> on the bar. (I just checked)
>>
>> So why is it appearing in the lists for today? And all of those going
>> back over the past day or so?
>>
>> Simple answers only please - type slowly .......
>>
>> Puzzled 73
>> Terry
>>
>>
>> Date: Wed, 29 Jun 2011 13:37:07 +0200
>>> From: "Mike Zwingl oe3mzc"<oe3mzc at oevsv.at>
>>> Subject: [OZAPRS] QRG drift HF APRS
>>> To: "Australian APRS Users"<ozaprs at aprs.net.au>
>>> Message-ID:<00ed01cc3650$e08f6800$cda8a8c0 at WORKSTATION>
>>> Content-Type: text/plain; charset="iso-8859-1"
>>>
>>> see how all stations on 10Mhz are drifting offset in QRG:
>>> http://aprs.fi/?c=raw&call=vk6uz-4
>>> It is not the absolute but the relative value to each other that
>>> makes the problem in decoding hf-aprs sigs.
>>> (values after callsigns is given in Hz)
>>>
>>> 2011-06-29 11:24:57 UTC:
>>> VK6UZ-4>APU25N,TCPIP*,qAC,T2AUST:=3211.17S/11604.17E&HF-IGATE
>>> 10147.6USB Perth
>>> 2011-06-29 11:29:01 UTC: VK6UZ-4>APRS,TCPIP*,qAC,T2AUST:>dF (Hz):
>>> WIDE1 +100, VK2GKA-15 +50, VK7BW-15 +50, VK8ZAB-4 +25
>>> 2011-06-29 11:29:02 UTC: VK6UZ-4>APRS,TCPIP*,qAC,T2AUST:>dF (Hz):
>>> VK4UN-4 +62, VK5ATN-15 +65, VK5LY-15 +43, VK4KWI-15 +75
>>> 2011-06-29 11:29:02 UTC: VK6UZ-4>APRS,TCPIP*,qAC,T2AUST:>dF (Hz):
>>> VK2AJ-15 +50, KF7EU-6 +25, ZS6SS-3 +62, VK2TV-4 +143
>>> 2011-06-29 11:29:02 UTC: VK6UZ-4>APRS,TCPIP*,qAC,T2AUST:>dF (Hz):
>>> VK3DHI-15 +68, VP8DEU +43, VK2DQC-15 +81, VK4DMI-4 +96
>>> 2011-06-29 11:29:02 UTC: VK6UZ-4>APRS,TCPIP*,qAC,T2AUST:>dF (Hz):
>>> VK4HW-15 +46, VK4VP-15 +25, DL8RCB-3 +100, IW2GOB-10 +100
>>> 2011-06-29 11:29:02 UTC: VK6UZ-4>APRS,TCPIP*,qAC,T2AUST:>dF (Hz):
>>> VK4KMR-15 +46, F5LDS-4 +112, VK2SX-15 +50, LA4FPA-15 +87
>>> 2011-06-29 11:29:02 UTC: VK6UZ-4>APRS,TCPIP*,qAC,T2AUST:>dF (Hz):
>>> VK7DIK-4 +40, VK3MY-4 +65, VK3BZQ-9 +37, VK5LY-4 +43
>>> 2011-06-29 11:29:02 UTC: VK6UZ-4>APRS,TCPIP*,qAC,T2AUST:>dF (Hz):
>>> VK4UN-15 +43, VK8LM +50, VK5LY-6 +50, VK3BDG-9 -18
>>>
>>
>>
>>
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