[OZAPRS] APRS sat settings

Bob Cameron bob3bob3 at skymesh.com.au
Sun Dec 4 15:43:27 AEDT 2022 

Ray/All

VK2YQA-12

For interest if anyone wants to analyse some raw packets over the last 
few weeks. I beacon twice every 10 minutes only when mobile. I bumped up 
the power to about 60W for the crossing. It was almost 100% reliable up 
to about Balladonia, Using an Outbacker 1.8m whip and the default 
Direwolf frame etc stuff.

I am currently near Kalgoorlie and (only) VK5ARG is decoding me maybe 
1/3 the time on 30m. I'll be doing circles and zigzags around SW WA for 
the next month or two.

Cheers Bob

On 11/11/22 11:24, vk2tv wrote:
> Are there any satgates within 100km of Sydney that would cause a 
> problem for their "local" stations? In my years of running a satgate I 
> don't remember logging very many Sydney stations through ISS, PSAT, 
> Bricksat, et al. The stations I usually gate are in vk5, vk3, vk4, vk1 
> and zl, and all a long way from here, making me a non-"threat" :) One 
> exception is VK2EVB in Coffs Harbour (100+km) whom I can't hear direct.
>
> The path "VIA=ARISS,SGATE,WIDE2-1" certainly doesn't create issues 
> other than it makes the packet longer which "might" make it more 
> vulnerable to not being decoded. If that path works for any particular 
> individuals, use it.
>
> As for HF aprs I fully endorse the value of using 30m, for those whose 
> licence permits it. I ran 30m aprs for a number of years when out on 
> the farm, logging aprs stations from all over Oz, Europe, the 
> Caribbean and down near Antarctica. I also had a 40m port for aprs, 
> and I tried 20m too - three separate rigs. 20m was a dead loss with a 
> dipole antenna, and 40m was way too noisy - atmospheric. My site noise 
> was always S0.  Prior to turning to 30m aprs I ran a HF BBS and 30m 
> walked all over 20m and 40m for reliability for Oz paths. The down 
> side to 30m is that it tends to be somewhat unreliable and 
> unpredictable for distances less than about 500km, that finding after 
> considerable years of BBS and aprs service.
>
> A bit OT for the topic, but relevant to the conversation for best HF 
> performance: to enhance the success rate of HF packet (including 
> aprs), keep packets short. Parameters such as maxframe, paclen and 
> frack settings are not what one would use on VHF, and "better suited" 
> values make a world of difference on HF.
> maxframe - use 1.  Better to get one packet through than to lose 2 or 
> more!
> paclen - maximum of 64 but preferably 32 or 48.   Same rationale as 
> above!
> frack - use 13 seconds.   This one made the world of difference. A 
> typical VHF setting of 3 to 7 seconds would retry out, almost 
> predictably when the band was noisy or badly affected by phase 
> distortion. Longer frack time didn't eliminate those issues but did 
> provide a better "buffer" against their effects.
>
> Consider setting a txtail value (try 200mS and adjust as necessary) to 
> ensure the end of the data stream isn't cut off by a tx dropping off 
> before the packet has been cleared. I had zilch success on HF without 
> some txtail time.
>
> The channel access parameters listed were arrived at courtesy of 
> Flexnet, the German packet software from the 90s, that dynamically 
> auto-set the parameters listed above, and it was Flexnet that 
> repeatedly arrived at those figures that served me well for some 
> years, long after I shifted the system to Linux and kernel ax25.
>
> HTH
>
> Ray vk2tv
>
>
>
> On 10/11/22 22:14, Terry wrote:
>> The seems to be diversity of paths used for the ISS.  I think Ray's 
>> observation (VK2TV) is pretty well on the money.
>>
>> However AFAIK the ISS is the only satellite operational at present, 
>> and even then the digipeater goes 'off air' at times for a variety of 
>> reasons - EVA / docking with another spacecraft / school contacts and 
>> other events.  It's currently been off air for nearly five days as I 
>> write, so it's not as reliable as one might hope ( I speculate that 
>> sometimes they simply forget to turn it back on again). The other 
>> factor can be that its orbits over a given spot on the earth's 
>> surface are such that a mobile station might only be heard for a 
>> series of two or three passes in any given 24 hours.   There are 
>> (from memory) about three satgates in the SW of WA and from what I 
>> can see, VK5ATN-3 is the only one in SA.   There are a few more in 
>> the eastern states one in Tassie. The coverage over AU is pretty good 
>> but a satgate in the northern part of the continent would be welcome 
>> to fill the gaps that do exist. Even so, some satgates in Indonesia 
>> do have a reach which does extend coverage into the northern and 
>> central  parts of WA.
>>
>> Personally I would still choose 30m for that kind of trip - I think 
>> that on balance you'd be 'seen' far more often on there than what the 
>> ISS is able to offer.  In the meantime keep an eye on 
>> http://www.ariss.net/  and watch the orbits on a program of your 
>> choice.   At present, the ISS offers useful daytime passes for 
>> Australia, but in time that will change (as it does) to passes 
>> possibly less favourable for the intended purpose.
>> 73
>> Terry
>> VK5ATN
>>
>>
>>
>> On 10/11/2022 4:38 pm, vk2tv wrote:
>>> I don't know if anything more than just VIA=ARISS is "really" needed 
>>> in today's environment. Comments from anyone??? My satgate (near 
>>> Kempsey), one of a few in Oz, just listens for traffic on 145.825 
>>> and gates it to the aprs-is.
>>>
>>> Ray vk2tv
>>>
>>>
>>>
>>> On 10/11/22 16:47, Bob Cameron wrote:
>>>> Just wanted to check this. One never knows how dated Internet info is.
>>>>
>>>> I successfully beacon on 30m on my VK travels (permanently on 
>>>> road). I am about to wander over to VK6. The 30m will be a good 
>>>> test of the usual VK5 IGate I get into as it seems there is no 30m 
>>>> RX/igate in VK6.
>>>>
>>>> I do however want to setup a fallback to use satellite and wanted 
>>>> to check if;
>>>>
>>>> VIA=ARISS,SGATE,WIDE2-1
>>>>
>>>> is valid. Would someone please verify this for me?
>>>>
>>>> Tnx Bob VK2YQA-12
>>>>
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