[aprssig] Advice requested please

Chris Moulding chrism at crosscountrywireless.net
Tue May 7 03:56:01 CDT 2013


Gregg,

Thanks for your reply.

I've redesigned the device firmware and the Android app from this 
perspective and it's fixed the problem.

There will of course be a lot of testing before any release to make sure 
it's OK.

Regards,

Chris, G4HYG

--
Chris Moulding
Cross Country Wireless
7 Thirlmere Grove, Bolton, Lancs, BL4 0QB, UK
Tel/fax:     +44(0)1204 410626
Mobile:      +44(0)7752 391908
Website:     http://www.crosscountrywireless.net
Yahoo group: http://uk.groups.yahoo.com/group/cross_country_wireless/

On 06/05/2013 15:53, Gregg Wonderly wrote:
> In computer networking, this is a layer-3 problem.  Layer 1 is bluetooth.  Layer 2 is the serial stream.  So you really need to consider how to provide a valid end-to-end stream across that network so that your application works as expected.  Only complete packets should traverse the network, because your application depends on that data being complete/correct.
>
> If you were going to add the ability to send command/control between the android app and the Digi-Tracker, then you would be introducing a layer-4, application protocol.  For example, if you had a configuration file on the digi tracker that you wanted to update from the android app, then you'd need to introduce a layer-4 protocol that would allow you to designate the difference between data destined for the TNC (if it was able to transmit packets) and data that would overwrite the configuration.
>
> If you will think about your design from this perspective, it will help you separate concerns and create great software that does exactly what you need it to do.
>
> Gregg Wonderly
> W5GGW
>
> On May 5, 2013, at 12:40 PM, Chris Moulding <chrism at crosscountrywireless.net> wrote:
>
>> Thanks for all the suggestions, I'll consider all of them.
>>
>> The Digi Tracker outputs TNC2 packets so the Android program at present is a simple Bluetooth serial connection with a TCP/IP connection for igating to the APRS-IS.
>>
>> I've also found a way of reliably testing a poor Bluetooth connection so I can test all the possible solutions.
>>
>> Regards,
>>
>> Chris, G4HYG
>>
>>
>>
>> --
>> Chris Moulding
>> Cross Country Wireless
>> 7 Thirlmere Grove, Bolton, Lancs, BL4 0QB, UK
>> Tel/fax:     +44(0)1204 410626
>> Mobile:      +44(0)7752 391908
>> Website:     http://www.crosscountrywireless.net
>> Yahoo group: http://uk.groups.yahoo.com/group/cross_country_wireless/
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>> http://www.tapr.org/mailman/listinfo/aprssig
>
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