[OZAPRS] 9600 baud

[Darryl Smith]

Hi Howard

Many reasons

* 1200 bps is much cheaper to set up given availability of TNC's and the like
* Keyup and key down times are the major timing issue with APRS. 9600 bps does not make the transmission much shorter
* Eb/N0 is probably the main reason. This is engineering speak for saying that the reliability improves with more transmission power. Imagine 120W being used. At 1200 bps, this becomes 0.1 W / bps. At 9600, it becomes 0.0125 W / bps. This is 1/8th of the power per bit, with a consequent increase in packet loss

Darryl


---------
Darryl Smith, VK2TDS POBox 169 Ingleburn NSW 2565 Australia 
Mobile Number 0412 929 634 [+61 4 12 929 634 Int] - 02 9618 6459 
www.radio-active.net.au/blog/ - www.radio-active.net.au/

-----Original Message-----
From: ozaprs-bounces at aprs.net.au [mailto:ozaprs-bounces at aprs.net.au] On Behalf Of Howard Small
Sent: Wednesday, 12 January 2011 5:10 AM
To: OZAPRS at aprs.net.au
Subject: [OZAPRS] 9600 baud

Just wondering why we use 1200 baud for APRS and not 9600? I must say that doing some tests with 9600 between my D700, D7, D72 and VX-8R has not shown it to be reliable but wonder if that is general or just something specific to some of the equipment...

Howard
VK4BS



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