[OZAPRS] VK2HAB 25/05/16

Tue May 31 09:33:48 AEST 2016

Kewl,
On it now! Already have a turnstile over ground plane left over from when
AMSAT ops were interesting, tho Bob Bruninga's efforts with NO-84 have
rekindled some interest.

Have a good one
norm
vk3xci

On Mon, May 30, 2016 at 6:41 PM, Mark Jessop <lenniethelemming at gmail.com>
wrote:

> On the balloon we currently have a 1/4 wave monopole with ground radials.
>
> On the ground (At least on matt's car) there is a crossed-dipole, mainly
> for the hemispherical radiation pattern (no null directly overhead), but
> the circular polarisation can help when the payload is tumbling (reduces
> the depth of the nulls)
>
> - Mark VK5QI
>
> On Mon, May 30, 2016 at 11:46 AM, Norm McMillan <vk3xci at gmail.com> wrote:
>
>> 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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