[OZAPRS] Setting up TT4 Tx on 2m and more! Problem Solved
David and Justine Olsen
davejust at bigpond.net.au
Thu Feb 18 18:23:24 EST 2010
Not so Norm
The baud rate in UIView was set too low meaning the Rx wasn't getting
to UIview.
The TT4 problem I described before was without UIView connected.
It has since been gated by one station but it should be doing better
than that with 13m high antenna and depending on my testing either 5W
or 25W, so it isn't a baud rate issue causing the TX problems
David
On 18 Feb 2010, at 16:53, Norm, VK3XCI wrote:
> Told you so :>
>
>
>
>
>
> 73 de Norm, VK3XCI
> Mildura, Australia
> The Wintersun City
> QF15bt.
>
> David and Justine Olsen wrote:
>> When in doubt, check the baud rate <blush>
>>
>> David
>>
>> On 18 Feb 2010, at 12:29, David and Justine Olsen wrote:
>>
>>> Too late for my hair Ray.
>>>
>>> I've moved on to the other part of my project now, and will go back
>>> over your email when I get back to the TT4 Tx issue.
>>>
>>> I've got a tracker to install in my aircraft an 8W unit from Byon. I
>>> want to set up a portable computer EEPC with TT4 and UIview at the
>>> gliding club, have a tracker in my glider and have its position
>>> shown
>>> on the EEPC.
>>>
>>> I'm running it now and it is being decoded by the TT4 via a Kenwood
>>> TM201A. I can see the decodes in Hyperterminal, of my tracker and
>>> other local APRS transmitters when TT4 is in text and when TT4 is in
>>> KISS mode. In KISS mode the first part of the transmission is
>>> gibberish in Hyperterminal - no problems.
>>>
>>> My problem is how to setup UIView in KISS mode to receive data from
>>> the TT4. The TT4 is setup in Alpha mode.
>>>
>>> As I said, Hyperterminal shows data received via the serial port,
>>> but
>>> I can;t get anything to appear in UIView.
>>> Can anyone point me to UIview KISS setup for TT4?
>>>
>>> Thanks for the audio stuff....I'll file it away for when I get
>>> back to
>>> that part of the project.
>>>
>>> David
>>>
>>>
>>>
>>>
>>> On 18 Feb 2010, at 12:14, Ray Wells wrote:
>>>
>>>> David/All,
>>>>
>>>> I'm not suggesting your problem is tone level related but
>>>> failure to
>>>> grasp the following is arguably responsible for more TNC decode
>>>> issues than any other cause.
>>>>
>>>> The need for "twist" adjustment depends on the radio hardware
>>>> involved so a brief discussion is probably in order.
>>>>
>>>> The "norm" for an FM/PM radio is to apply 6dB (x2) per octave of
>>>> preemphasis in the transmitter. For packet, this results in the
>>>> high
>>>> tone (2200Hz) having twice (near enough) the deviation as the low
>>>> tone (1200). In the receiver deemphasis is applied which
>>>> restores the
>>>> audio to a "flat" condition, i.e. both tones going to the TNC have
>>>> the same level.
>>>>
>>>> If TNC audio is fed into the microphone socket you can depend on
>>>> 6dB
>>>> per octave preemphasis. However, if the TNC audio is fed in further
>>>> down the tx audio chain, such as the audio injection point for tone
>>>> signalling, preemphasis will not be applied in the tx and should be
>>>> applied externally - with twist, in the case of the TT4.
>>>>
>>>> Going to the receiver again, if it receives a signal without
>>>> preemphasis, it will still apply deemphasis (assuming audio is
>>>> taken
>>>> after deemphasis), resulting in the high tone being just half the
>>>> level of the low tone when fed to the TNC. FSK demodulators
>>>> based on
>>>> the the exar pair 2206/2211 will not decode if the high tone is
>>>> lower in amplitude than the low tone, by even a very small amount.
>>>>
>>>> If rx audio is taken from the demodulator in the radio, i.e. before
>>>> deemphasis, the preceding is not a problem because audio that is
>>>> transmitted "flat" will be decoded "flat".
>>>>
>>>> The exar chip set (found in genuine TNC2 TNC's) is not
>>>> disturbed by
>>>> high tone being considerably higher in amplitude than the low tone.
>>>>
>>>> In summary, every tx should employ preemphasis, regardless of it
>>>> being generated internally, or externally. That will eliminate any
>>>> decode problems in TNC's with finicky chip sets because high tone
>>>> will always be the same level as, or higher than, the low tone
>>>> coming
>>>> out of the rx.
>>>>
>>>> David, is TXD 60 60mS or 600mS? Although TXD provides time for your
>>>> tx to stabilise before valid data is sent, it can also have an
>>>> impact
>>>> on the remote rx in cases where muted audio is being used for the
>>>> TNC. There are some very sluggish receivers kicking about and TXD
>>>> needs to be long enough for that rx to unmute. My Icon handheld
>>>> scanner is pathetic in this regard, with the mute being so slow
>>>> that
>>>> I can miss at least half of the digi beacon, even when I'm at the
>>>> digi site.
>>>>
>>>> Get that CRO working and save your hair, lest you should end up
>>>> like
>>>> me :-)
>>>>
>>>> Ray vk2tv
>>>>
>>>>
>>>>
>>>> David and Justine Olsen wrote:
>>>>> I am presently running TxD of 60 and TXTWIST of 50. I've tried a
>>>>> range of TXTWIST but none sound too different
>>>>> David
>>>>>
>>>>> On 18 Feb 2010, at 00:36, Scott Evans wrote:
>>>>>
>>>>>>
>>>>>> ABAUD is just the speed set for serial port 1 ... what TXDELAY
>>>>>> are
>>>>>> you running? because depending on how quick you radio is you may
>>>>>> need to lengthen the delay a little, also check the TXTWIST
>>>>>> setting
>>>>>> too, this controls the level between the 1200Hz & 2200Hz tones.
>>>>>>
>>>>>> On Wed, 2010-02-17 at 21:51 +1000, David and Justine Olsen wrote:
>>>>>>> ABAUD is set to 19200
>>>>>>>
>>>>>>>
>>>>>>> On 17 Feb 2010, at 21:37, Norm, VK3XCI wrote:
>>>>>>>
>>>>>>>> Sort of like 9600 baud?
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>> 73 de Norm, VK3XCI
>>>>>>>> Mildura, Australia
>>>>>>>> The Wintersun City
>>>>>>>> QF15bt.
>>>>>>>>
>>>>>>>> David and Justine Olsen wrote:
>>>>>>>>> I've gone through all of the TT4 audio adjustments as
>>>>>>>>> explained in
>>>>>>>>> the help docs by listening on another set, but still no
>>>>>>>>> success being
>>>>>>>>> received by any digis.
>>>>>>>>>
>>>>>>>>> One thing that has me curious, is the the squak from my Tx
>>>>>>>>> sounds
>>>>>>>>> nothing like those from others. The others are a deehdaaah
>>>>>>>>> kind of
>>>>>>>>> sound with two distinctly different tones ate the beginning
>>>>>>>>> and end
>>>>>>>>> tone, whereas mine is a sqaaaark :-) of mixed tones at the
>>>>>>>>> same time.
>>>>>>>>>
>>>>>>>>> David
>>>>>>>>>
>>>>>>>>> VK4MDX
>>>>>>>>>
>>>>>>>>> _______________________________________________
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>>>>>>
>>>>>> --
>>>>>> Scott Evans <scott at vk7hse.hobby-site.org
>>>>>> <mailto:scott at vk7hse.hobby-site.org>>
>>>>>>
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