[OZAPRS] HF Gateways
Ray Wells
vk2tv at exemail.com.au
Mon Jun 29 18:06:32 EST 2009
Jamie,
I'd never made the TCP/IP vs UDP comparison but, yes, close enough.
With numbered ax25 frames the "within reason" is determined by RETRY
which is typically 10. Is the TCP/IP equivalent the TTL (Time To Live)
parameter?
I don't use Echolink or VoIP so can't comment. Come to think about it, I
don't use microphones on anything. I send everything just like in morse
code - digitally :-)
Ray vk2tv
Jamie Campbell - VK2YCJ wrote:
> Ray,
>
> Ah, I see. Very Interesting stuff.
>
> In Internet terms we could say that they are similar to TCP/IP and UDP
> packets. Most Internet things use TCP/IP as it gives a guarantee of
> delivery. UDP is used for things like VOIP where time is of the
> essence and packets are sent but not checked to see if they are
> delivered. Typically TCP/IP will keep on resending to get the data
> through (within reason). UDP will try once, but there are exceptions
> where certain applications like username and password authentication
> where the application will send the UDP packet 3 times in case it goes
> missing. That way you have 3 chances of losing the packet.
>
> I suspect that Echolink doesn't use a standard VOIP UDP protocol
> because I have NEVER heard a crook Echolink transmission. I'm
> guessing, but because it is a simplex transmission with a bit of
> buffering they can probably use TCP/IP to guarantee delivery and the
> buffering covers up any instability or jitter that might affect the
> quality at the other end.
>
> I'm thinking aloud here ....
>
>
>
> Jamie Campbell
> vk2ycj at bravo.net.au
>
>
> You'll never reach your greatest potential if you walk
> past the dishwasher without emptying it or leave your
> costume on the bathroom floor.
>
> (Nancy-Bird Walton, Australian Aviatrix, 1915-2009)
>
>
> ----- Original Message ----- From: "Ray Wells" <vk2tv at exemail.com.au>
> To: "Australian APRS Users" <ozaprs at aprs.net.au>
> Sent: Monday, June 29, 2009 3:49 PM
> Subject: Re: [OZAPRS] HF Gateways
>
>
>> BBS operation is a little different from APRS in that if a frame
>> isn't received/acknowledged, it's sent again. The UI frames of APRS
>> are launched into the never never with no guarantee of delivery.
>>
>> BBS operation also has an advantage over two operators trying to have
>> a digital contact because if frames aren't received now, they might
>> be later, possibly hours later. Even the "dead at night" nature of
>> 40m delivers some frames in that "dead" time. It's not unusual to
>> hear the 40m rig forwarding at 1.00am - the shack is in the house and
>> I hear the PTT relay going, and the reply packet.
>>
>> Ray vk2tv
>>
>> Jamie Campbell - VK2YCJ wrote:
>>> Ray,
>>>
>>> What an interesting story. I enjoyed reading it and chuckled on the
>>> way through. Thanks for the snapshot of your 10 years of packet.
>>> I'm going to tag this email and come back and read it again so I can
>>> absorb it.
>>>
>>> I guess with APRS the amount of data being sent is quite small
>>> compared to a slow scan image or digital file. Being small probably
>>> gives it an advantage in getting through particularly with the data
>>> packet techniques you mentioned.
>>>
>>> Thanks again for the story ...
>>>
>>>
>>> Jamie Campbell
>>> vk2ycj at bravo.net.au
>>>
>>>
>>> You'll never reach your greatest potential if you walk
>>> past the dishwasher without emptying it or leave your
>>> costume on the bathroom floor.
>>>
>>> (Nancy-Bird Walton, Australian Aviatrix, 1915-2009)
>>>
>>>
>>> ----- Original Message ----- From: "Ray Wells" <vk2tv at exemail.com.au>
>>> To: "Australian APRS Users" <ozaprs at aprs.net.au>
>>> Sent: Monday, June 29, 2009 2:31 PM
>>> Subject: Re: [OZAPRS] HF Gateways
>>>
>>>
>>>> Jamie,
>>>>
>>>> Each of us who has reported their experiences with 80m are
>>>> reporting just that, their experiences. We all know how Mother
>>>> Nature can be with propagation and experiences that contradict my
>>>> own don't surprise me.
>>>>
>>>> What does surprise me are comments that HF packet won't work for
>>>> this, that or another reason. Sometimes those comments are from
>>>> people who haven't actually used it. Sure it has its limitations at
>>>> times but it can be surprisingly good.
>>>>
>>>> I've been using 0k3 HF for BBS forwarding for over ten years on a
>>>> 24/7 basis so I'm probably reasonably well qualified to comment. My
>>>> initial activity was on 30m when I forwarded with a vk3, and later
>>>> with a vk5. Both paths were consistently open 22 hours per day.
>>>> About seven (maybe six) years ago I started using 40m between
>>>> Kempsey and Sydney (vk2aab), with great success. Steve (vk2slm) in
>>>> Casino joined us maybe two years ago. I forwarded with another
>>>> station in Forbes for a while. Steve and Barry are each a similar
>>>> distance from me, but in opposite directions. Propagation over
>>>> those two paths is quite different.
>>>>
>>>> The two factors that influence performance the most are static
>>>> crashes and phase distortion. Provided a storm isn't too severe it
>>>> is still possible
>>>> to forward data. Phase distortion is something else again. There
>>>> can be S9+ signals but no data gets exchanged. Frustrating to say
>>>> the least. An important factor for HF packet is to keep paclen low.
>>>> I use paclen 64 and maxframe 1, those values being arrived at
>>>> empirically. FRACK also needs to be set high to reduce retrying
>>>> out. I run about 13 seconds. The shorter the frame the greater the
>>>> chance of getting through. And maxframe one ensures that multiple
>>>> packets don't have to be resent in the event of one corrupted packet.
>>>>
>>>> When I first started using HF on 30m I was using Flexnet which,
>>>> some of you may recall, automatically sets parameters such as
>>>> maxframe and frack. The vk3 path was so good that Flexnet would set
>>>> maxframe to 7. It was Flexnet that determined frack should be so long.
>>>>
>>>> Do you remember why amateurs were originally given HF? It was given
>>>> because governments believed we'd never get out of our own back
>>>> yards with such short wavelengths. We tried and succeeded. Apply
>>>> that philosophy to HF packet.
>>>>
>>>> Ray vk2tv
>>>>
>>>>
>>>> Jamie Campbell - VK2YCJ wrote:
>>>>> Ray,
>>>>>
>>>>> Good on you for making some positive comments on 80m. It's a good
>>>>> band during the day for some reasonable coverage. I get good
>>>>> reliaable coverage on 80m all day (during the daylight hours) -
>>>>> probably 300Km-400Km or so. The Dural morse code beacon near to
>>>>> 3.7 Mhz is generally S9/ +20 to +40db all day. Newcastle to
>>>>> Sydney and Kiama is dead easy too. Mid to late morning (9am-10am)
>>>>> often gives good but scratchy coverage Newcastle to Melbourne.
>>>>>
>>>>> Local noise levels would be a problem for a mobile station though.
>>>>>
>>>>>
>>>>>
>>>>> Jamie Campbell
>>>>> vk2ycj at bravo.net.au
>>>>>
>>>>>
>>>>> You'll never reach your greatest potential if you walk
>>>>> past the dishwasher without emptying it or leave your
>>>>> costume on the bathroom floor.
>>>>>
>>>>> (Nancy-Bird Walton, Australian Aviatrix, 1915-2009)
>>>>>
>>>>>
>>>>> ----- Original Message ----- From: "Ray Wells" <vk2tv at exemail.com.au>
>>>>> To: "Australian APRS Users" <ozaprs at aprs.net.au>
>>>>> Sent: Monday, June 29, 2009 12:19 PM
>>>>> Subject: Re: [OZAPRS] HF Gateways
>>>>>
>>>>>
>>>>>> I wouldn't write off 80m completely, even though its use would be
>>>>>> limited.
>>>>>>
>>>>>> Yes, the static crashes at night are a downer but if you're
>>>>>> looking at relatively short range - out to about 400km - and you
>>>>>> can erect an antenna, daytime 80m is remarkably good. Mind you, a
>>>>>> local daytime electrical storm has quite an impact too :-(
>>>>>>
>>>>>> When I did a lot of travelling with HF onboard, if I could erect
>>>>>> a dipole, albeit close to the ground, we regularly (read as
>>>>>> daily) worked out to 400km. Signal levels were often low but
>>>>>> there was usually little band noise so s/n ratio was high. FM was
>>>>>> performance was quite impressive compared with SSB. We did some
>>>>>> testing with narrow deviation.
>>>>>>
>>>>>> VK2AAB and I came very close to resorting to 80m for daytime BBS
>>>>>> forwarding some months back when 40m (our usual band) completely
>>>>>> died for quite some weeks. We're nearly 400km apart. 40m came
>>>>>> good and we didn't have to try 80m.
>>>>>>
>>>>>> Ray vk2tv
>>>>>>
>>>>>> VK2KFJ wrote:
>>>>>>> yeh pretty much the noise & static crashes, and its useless
>>>>>>> during daytime.
>>>>>>> I remember some guys trying packet radio on 80m years ago and
>>>>>>> they gave up that it was easier to pick up the microphone to get
>>>>>>> a message through.
>>>>>>>
>>>>>>> Steve VK2KFJ
>>>>>>>
>>>>>>>
>>>>>>> --- On Thu, 25/6/09, Jamie Campbell - VK2YCJ
>>>>>>> <vk2ycj at bravo.net.au> wrote:
>>>>>>>
>>>>>>>
>>>>>>>> From: Jamie Campbell - VK2YCJ <vk2ycj at bravo.net.au>
>>>>>>>> Subject: Re: [OZAPRS] HF Gateways
>>>>>>>> To: "Australian APRS Users" <ozaprs at aprs.net.au>
>>>>>>>> Received: Thursday, 25 June, 2009, 10:49 AM
>>>>>>>> Steve,
>>>>>>>>
>>>>>>>> Thanks for the reply.
>>>>>>>>
>>>>>>>> Would you not bother with 80m because of the noise (mainly
>>>>>>>> at night) or the relatively short range during the day ?
>>>>>>>>
>>>>>>>> Okay, does that mean that 40m is the most popular at
>>>>>>>> present ?
>>>>>>>>
>>>>>>>> 40m isn't too crash hot now with the sunspot cycle the way
>>>>>>>> it is, although if there was an abundance of base stations the
>>>>>>>> coverage
>>>>>>>> could be extremely good.
>>>>>>>>
>>>>>>>> With a few dozen $150 boxes around the place we could have
>>>>>>>> "armchair coverage" across Australia, haha :)
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>> Jamie Campbell
>>>>>>>> vk2ycj at bravo.net.au
>>>>>>>>
>>>>>>>>
>>>>>>>> You'll never reach your greatest potential if you walk
>>>>>>>> past the dishwasher without emptying it or leave your
>>>>>>>> costume on the bathroom floor.
>>>>>>>>
>>>>>>>> (Nancy-Bird Walton, Australian Aviatrix, 1915-2009)
>>>>>>>>
>>>>>>>>
>>>>>>>> ----- Original Message ----- From: "VK2KFJ" <vk2kfj at yahoo.com.au>
>>>>>>>> To: <Ozaprs at aprs.net.au>;
>>>>>>>> "Australian APRS Users" <ozaprs at aprs.net.au>
>>>>>>>> Sent: Thursday, June 25, 2009 10:28 AM
>>>>>>>> Subject: Re: [OZAPRS] HF Gateways
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>> Hi Jamie,
>>>>>>>>>
>>>>>>>>> you just wouldn't bother with 80m,
>>>>>>>>>
>>>>>>>>> however, you on the right track at looking at cheap
>>>>>>>>>
>>>>>>>> dedicated xcvr,
>>>>>>>>
>>>>>>>>> I have been thinking about it myself,
>>>>>>>>>
>>>>>>>>> so what you could do is take the 80m xcvr and
>>>>>>>>>
>>>>>>>> modify/adapt it to work on
>>>>>>>>> 40m.
>>>>>>>>>
>>>>>>>>> Any radio can be made to work anywhere, its just a
>>>>>>>>>
>>>>>>>> matter of how much
>>>>>>>>> time, money & effort you want to put into it.
>>>>>>>>>
>>>>>>>>> cheers,
>>>>>>>>>
>>>>>>>>> Steve VK2KFJ, Sydney Australia. http://www.qsl.net/vk2kfj/
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> --- On Tue, 23/6/09, Jamie Campbell - VK2YCJ
>>>>>>>>> <vk2ycj at bravo.net.au>
>>>>>>>>>
>>>>>>>> wrote:
>>>>>>>>
>>>>>>>>>> From: Jamie Campbell - VK2YCJ <vk2ycj at bravo.net.au>
>>>>>>>>>> Subject: [OZAPRS] HF Gateways
>>>>>>>>>> To: Ozaprs at aprs.net.au
>>>>>>>>>> Received: Tuesday, 23 June, 2009, 6:21 PM
>>>>>>>>>> Gudday,
>>>>>>>>>>
>>>>>>>>>> If one was going to build a dedicated box (rx/tx)
>>>>>>>>>>
>>>>>>>> and
>>>>>>>>
>>>>>>>>>> antenna system for the car for APRS, what would be
>>>>>>>>>>
>>>>>>>> the most
>>>>>>>>
>>>>>>>>>> appropriate HF band to use ? 40m, 30m, 20m
>>>>>>>>>> ?
>>>>>>>>>>
>>>>>>>>>> Does anyone ever use 80m for APRS ? Why
>>>>>>>>>> not ?
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> The boys at the Mid North Coast Amateur Radio Club
>>>>>>>>>>
>>>>>>>> (
>>>>>>>>>> http://www.mncarg.org ) have recently bought some kits
>>>>>>>>>> for a small 80m 5W SSB Tranceiver. It's a very
>>>>>>>>>>
>>>>>>>> neat
>>>>>>>>
>>>>>>>>>> little kit and costs about $150. At that price
>>>>>>>>>>
>>>>>>>> and
>>>>>>>>
>>>>>>>>>> size it would be ideal for a standalone APRS box,
>>>>>>>>>>
>>>>>>>> but I am
>>>>>>>>
>>>>>>>>>> not sure if the kit is available for other bands.
>>>>>>>>>>
>>>>>>>>>> Any comments or suggestions appreciated.
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> Thanks ...
>>>>>>>>>>
>>>>>>>>>> Jamie Campbell
>>>>>>>>>> vk2ycj at bravo.net.au
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> You'll never reach your greatest potential if you
>>>>>>>>>>
>>>>>>>> walk
>>>>>>>>
>>>>>>>>>> past the dishwasher without emptying it or leave
>>>>>>>>>>
>>>>>>>> your
>>>>>>>>
>>>>>>>>>> costume on the bathroom floor.
>>>>>>>>>>
>>>>>>>>>> (Nancy-Bird Walton, Australian Aviatrix,
>>>>>>>>>>
>>>>>>>> 1915-2009)
>>>>>>>>
>>>>>>>>>> _______________________________________________
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>>>>>>>>>> http://aprs.net.au/mailman/listinfo/ozaprs
>>>>>>>>>>
>>>>>>>>>>
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>>>>>>>>>
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>>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
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>>>>>>
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