[OZAPRS] VK2HAB 25/05/16

Norm McMillan vk3xci at gmail.com
Mon May 30 12:16:16 AEST 2016


Mark Jessop said

>* "Linear at one end and circular at the other is exactly how we do it
right now."*

I'm missing something here, maybe 'cause I've been on holiday and "lost the
thread" hihi.

What is the actual antenna on the balloon?

What do you use for a receive antenna?

Is there a HAB website?


norm

vk3xci

On Mon, May 30, 2016 at 12:09 PM, Mark Jessop <lenniethelemming at gmail.com>
wrote:

> Linear at one end and circular at the other is exactly how we do it right
> now. :-)
>
> - Mark VK5QI
> On May 30, 2016 11:16 AM, "Norm McMillan" <vk3xci at gmail.com> wrote:
>
>> Mathew VK5ZM said
>> >" No circular polarised antennas are not the solution"
>> Boy, there's a can of worms right there, just waiting to be opened.
>> Sherman, crank up the Way Back Machine!
>>
>> In the days of AO-10, 13 etc a LOT of work went into circular, v oblique
>> v linear poz. Seems for satellite work, when the squint angle was
>> constantly shifting, matched sense circular poz at each end provided the
>> best compromise, about 3db loss max from true circular to oblique to
>> linear.. Trouble is, the sense reversed as the bird went overhead, so
>> switching poz sense was required at the ground station.
>>
>> Next best, circular to linear, 3db again and no need to switch sense.
>> Unfortunately, the incoming sig was not always true circ. poz., often
>> oblique, so 6db is a closer figure.
>>
>> Worst... linear to linear cross poz, around 20 to 30 db loss, and
>> circular to circular crossed sense, 30 to 60 db loss.These are pretty much
>> real world empirical figures... like I said... a LOT of work.
>>
>> Seems to me the best compromise would be linear at one end (balloon) and
>> circular at the other. On the other hand if it aint broke, don't fix it :-)
>>
>> Radiation pattern is a different story.
>>
>> Maybe we need a new thread?
>>
>>
>> norm
>> vk3xci
>>
>> On Sun, May 29, 2016 at 11:27 PM, Matthew Cook <vk5zm at bistre.net> wrote:
>>
>>> I'd suggest you research polarisation of antennae a little more and then
>>> think about that some more.  No circular polarised antennas are not the
>>> solution.
>>>
>>> 73
>>>
>>> Matthew
>>> VK5ZM
>>>
>>> On 29 May 2016 at 05:59, Andrew Rich <vk4tec at tech-software.net> wrote:
>>>
>>>> Hang a yagi looking back at earth
>>>>
>>>> -----------------------------
>>>> Sent from my iPhone
>>>> Andrew Rich
>>>> vk4tec at tech-software.net
>>>> www.tech-software.net
>>>> 0419 738 223
>>>>
>>>> On 26 May 2016, at 11:08, Matthew Cook <vk5zm at bistre.net> wrote:
>>>>
>>>> Hi Norm,
>>>>
>>>> That sounds about right with respect to range, height is might !
>>>>
>>>> Also don't forget that if you've got local traffic on a digi that this
>>>> will tromp on a balloon payload even at altitude.  It all comes down to
>>>> sneaking through the gaps.  Even with altitude you still have free space
>>>> path loss and the capture effect to contend with a the digi receiver.   It
>>>> is always sensible to run open squelch with software DCD if your packet
>>>> engine supports it.  That means weak signals don't have to crack the mute
>>>> of the radio first or get truncated if it drops too low.
>>>>
>>>> Another quirk with balloons is the antenna pattern at altitiude can
>>>> have severe nulls in it, so being directly under a balloon can make it very
>>>> difficult to decode (from bitter experience) when people 50km or more can
>>>> copy it fine.  YMMV.
>>>>
>>>> 73
>>>>
>>>> Matthew
>>>> VK5ZM
>>>>
>>>>
>>>>
>>>>
>>>> On 25 May 2016 at 17:44, Norm McMillan <vk3xci at gmail.com> wrote:
>>>>
>>>>> Thank you Mathew,
>>>>>
>>>>> 100,000 feet  is 30480meters, range 625km.
>>>>>  VK3RBT to VK2HAB 510 km.
>>>>>
>>>>> Seems odd that VK3RBT picked it up but not VK3RBX, which is closer.
>>>>> Better check the squelch/sensitivity on RBX I guess
>>>>>
>>>>> norm
>>>>> vk3xci
>>>>>
>>>>> On Wed, May 25, 2016 at 4:55 PM, Matthew Cook <vk5zm at bistre.net>
>>>>> wrote:
>>>>>
>>>>>> Norm,
>>>>>>
>>>>>> Yes 100,000ft for a HAB is not uncommon.  See if you can find an
>>>>>> online radio horizon calculator and punch in 100,000ft. Take the position
>>>>>> of the balloon when you received the posit and draw a circle around it from
>>>>>> the horizon calculator.  I'm fairly certain you'll find Bambil tanks is
>>>>>> within this circle.
>>>>>>
>>>>>> We regularly have VK3 stations receive our HAB telemetry with the
>>>>>> balloon 25kms or more in to the stratosphere.  Height is might !
>>>>>>
>>>>>> 73
>>>>>>
>>>>>> Matthew
>>>>>> VK5ZM
>>>>>> AREG/Project Horus
>>>>>>
>>>>>> On 25 May 2016 at 16:12, Norm McMillan <vk3xci at gmail.com> wrote:
>>>>>>
>>>>>>> Copied a few (20 or so) packets from this event. the path is
>>>>>>> interesting to say the least. Is there a digi not correctly identifying or
>>>>>>> did VK3RBT at Bambil Tank REALLY receive the balloon direct.
>>>>>>>
>>>>>>>
>>>>>>> 0:TNC->
>>>>>>> VK2HAB-11>APT314,VK3RBT-1,VK2RBX-1,WIDE2*:!3349.O1S/14701.26E0161/003/A=100594/UpLift
>>>>>>> Balloon Flights|$"!!!!|
>>>>>>>
>>>>>>> And did it really make it to 100594 feet?
>>>>>>> And what does the   |$"!!!!|   at the end mean. I noticed the first
>>>>>>> two characters change as the flight progressed
>>>>>>>
>>>>>>> Due to my inexperience with xastir I didn't log it, but I have a
>>>>>>> screen shot!
>>>>>>>
>>>>>>>
>>>>>>> norm
>>>>>>> vk3xci
>>>>>>>
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>>>>>>
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