[OZAPRS] Setting up TT4 Tx on 2m and more!
David and Justine Olsen
davejust at bigpond.net.au
Thu Feb 18 13:29:01 EST 2010
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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>>>> >> OZAPRS at aprs.net.au
>>>> >> http://lists.aprs.net.au/mailman/listinfo/ozaprs
>>>> >>
>>>> >>
>>>> >>
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>>>
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>>> Scott Evans <scott at vk7hse.hobby-site.org>
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