[OZAPRS] QRG drift HF APRS

Gerard Hill vk2io at amsat.org
Thu Jun 30 02:27:16 EST 2011


Hi All,

30m FSK300 APRS is a bit of a dog's breakfast at the moment. There is a 
wide dispersal of centre frequencies being used. It isn't being helped 
by the net stations being at least 50 Hz apart - no-one knows which one 
to tune to. I've given up chasing net stations down the band and now use 
WWV at 10 MHz as my reference. Its a continuous accurate transmission 
available 24 hours a day.

Its incumbent on the net stations to regularly check and retune their 
transmitters so that they are exactly on frequency. Crystals do age and 
radios do drift with temperature. The stations should be netted within 
10 Hz of each other. Please. This will give the other users (including 
IGates) a chance to net on the same frequency and the best chance of 
being heard.

Cheers ... Gerard, VK2IO

On 29/06/2011 10:49 PM, Richard Hoskin wrote:
> Hi Mike,
>
> The tuning information is interesting…….
>
> This is why we set up Net Stations several years ago. All VK HF APRS
> stations should tune to the designated NET station (see
> http://aprs.net.au/hf/hf-net-stations) By all HF APRS stations tuning to
> the NET station and not worrying about your radio’s frequency display
> everyone will be on the same wave length.
>
> In most cases there should be a Secondary Net station for each frequency
> in a different geographical location to the Primary Net station. This
> will allow for station to tune in to the Secondary Net station if they
> are unable to hear the Primary Net. The Primary and Secondary Net
> Stations would be frequency synchronised.
>
> Some of the Primary Net stations and Secondary Net stations have gone
> off the air over the years and have not been replaced. We may need a few
> volunteers to run their station as a 24/7/365 Secondary Net stations if
> they can hear the Primaries well enough to tune in accurately.
>
> It would be nice if VK6UK-4 wanted to setup as a Secondary Net station
> for 10MHz and tuned accurately to VK3MY-4.
>
> Cheers
>
> Richard
>
> *From:*ozaprs-bounces at aprs.net.au [mailto:ozaprs-bounces at aprs.net.au]
> *On Behalf Of *Mike Zwingl oe3mzc
> *Sent:* Wednesday, 29 June 2011 9:37 PM
> *To:* Australian APRS Users
> *Subject:* [OZAPRS] QRG drift HF APRS
>
> see how all stations on 10Mhz are drifting offset in QRG:
>
> http://aprs.fi/?c=raw&call=vk6uz-4 <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
> <http://aprs.fi/?c=raw&limit=&call=VK6UZ-4>*>APU25N,TCPIP*,qAC,T2AUST:=3211.17S/11604.17E&HF-IGATE
> 10147.6USB Perth
> 2011-06-29 11:29:01 UTC: *VK6UZ-4
> <http://aprs.fi/?c=raw&limit=&call=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
> <http://aprs.fi/?c=raw&limit=&call=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
> <http://aprs.fi/?c=raw&limit=&call=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
> <http://aprs.fi/?c=raw&limit=&call=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
> <http://aprs.fi/?c=raw&limit=&call=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
> <http://aprs.fi/?c=raw&limit=&call=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
> <http://aprs.fi/?c=raw&limit=&call=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
> <http://aprs.fi/?c=raw&limit=&call=VK6UZ-4>*>APRS,TCPIP*,qAC,T2AUST:>dF
> (Hz): VK4UN-15 +43, VK8LM +50, VK5LY-6 +50, VK3BDG-9 -18


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