[OZAPRS] HF frequency drift reports ...?

Thu Jun 30 20:31:06 EST 2011

Ray,
Accepted.
I don't want to discourage anyone from using Hf-APRS - on the contrary.

And to be fair- I just stepped into the discussion, because I saw someone's
MSG saying that he could not enter the network and was asking for reasons
(Power, antenna...) and in my experience it is often the frequency that is
not accurate, if you don't get relayed or gated.

It seems to me that the real reason is the price not technology.
You are asking a sponsorship, I will see what I can do,
but I have already donated one unit to ZS and one to V51...
and I am not earning bonus like bankers-hi

Sorry to have bothered you
73
Mike

-----Original Message-----
From: ozaprs-bounces at aprs.net.au [mailto:ozaprs-bounces at aprs.net.au] On
Behalf Of Ray Wells
Sent: Donnerstag, 30. Juni 2011 12:16
To: Australian APRS Users
Subject: Re: [OZAPRS] HF frequency drift reports ...?

Mike,

In my 13.5 years of running a BBS and in my last two years or so of running
a HF Igate I have found that for 99% of the time there is no need for an
expensive replacement for a standard, low cost TNC.

Mobile stations managed to access my BBS with a standard rig/TNC and my
heard list on 30m aprs is normally filled with stations from all over the
world.

I agree with Scott that, unless some kind person is prepared to donate
sufficient smart TNC's to cater for the entire Oz aprs network, let's leave
the hype alone for a while. All you are doing by promoting the smart TNC is
discouraging users and potential users who have standard equipment that will
work just fine nearly all of the time.

My comments are based on practical application over a long period of time,
not some specification sheet.

Ray vk2tv

On 30/06/11 19:31, OE3MZC Mike wrote:
> Hi Ray,
> all,
> I appreciate the discussion on this topic and accept your opinion.
> It is fair to say, that you can use a modern synthesized rig for 
> Hf-APRS, of course, But your statement also confirms my findings: you 
> need to be within plus/minus 40Hz- let's say 50Hz ok...
> depending on signal/noise ratio, signal levels and other distortion 
> from 230V/50Hz..
> If you doing at home, you can use a soundcard with waterfall display 
> or other means of tuning, no problem.
>
> If you do mobile out in bush things are much more complicated.
> Assume you use a TinyTracker or Opentracker and a FT857 or similar.
> The frequency in display will often be more than 100Hz offset from 
> real channel and the only way of tuning is to use the ECHO- command in 
> the digipath - which requires a laptop to change settings when driving
again...
> And considering drift caused by temperature changes in car you might 
> add another variable to the equation.
>
> However it would be much easier for mobiles if more I-Gates would have 
> 800Hz"wide band" receive capabilities...10times better.
> I think there is not just the SCS DSP-TNC that can do this, but also 
> some software for soundcard from G4hyg 
> http://www.crosscountrywireless.net/aprs_messenger.htm
> but I am not sure...
>
> Just for records: I am not related in any way to SCS, but using such a 
> device for years on Gateway OE3YCB-4 and OE3XUR and comparison to old 
> type Packet-Tncs is obvious.
> http://www.scs-ptc.com/downloads/pscproject.2008-09-29.7249707140/rele
> ases/1
> .0/scs-datasheet-tracker-english.pdf
> I have crossed Australia and Africa in 4WD using HF-APRS...so some 
> level of experience ...not just "hot-air" -hi
>
> Vy 73 de Mike
> VK3FPF/OE3MZC
>
> -----Original Message-----
> From: ozaprs-bounces at aprs.net.au [mailto:ozaprs-bounces at aprs.net.au] 
> On Behalf Of Ray Wells
> Sent: Donnerstag, 30. Juni 2011 10:35
> To: vk2io at amsat.org; Australian APRS Users
> Subject: Re: [OZAPRS] HF frequency drift reports ...?
>
> 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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>>
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