[aprssig] APRS on Smart Devices [WAS: APRN news from Dayton!]

Stephen H. Smith wa8lmf2 at aol.com
Tue May 24 14:32:18 EDT 2011

On 5/24/2011 9:37 AM, Julian, G4ILO wrote:
> I understand and agree with you Gregg but as a user of Lynn KJ4ERJ's
> APRSISCE in Windows Mobile and also an owner of several APRS RF
> devices I find myself in something of a dilemma. Do I use APRS over
> cellular and get all these improved features or do I stick true to the
> spirit of the hobby, use the radio and accept the limitations of the
> radio devices and the bandwidth?

The smart phone types seem to also forget that cellular "wireless" depends on 
VAST amounts of infrastructure - you must be within 5 miles or so of a cell 
site, for all these neat gadgets with their fractional-watt transmitters linked 
to low-performing hidden antennas  to work.     (It seems to be impossible now 
to get a cell phone with an actual exposed whip antenna or external antenna 
connector. )

Our clunky old low-bit-rate narrowband radios transmit 10s of watts (or more) 
into real antennas, results in vastly more robust long-distance communications.

I recently attended a seminar on conventional land mobile radio vs broadband 
"4G" LTE for public safety comms.   An interesting take on the differences I 
had never heard brought up before was contrasting the energy density per Hz of 
bandwidth (which ultimately determines the SNR at the receiver and data 
throughput achievable).    35 watts in a 20 KHz bandwidth for FM LMR vs a 
one-third-watt smeared out across 10 megahertz.for LTE.    The implication was 
that for comparable coverage area for the user in a large metro police dept or 
county sheriff's dept, you would require 10-20 times (!) the number of base 
station sites for LTE broadband; i.e. they would basically be building another 
cellular network.

> APRS over cellular is as much ham
> radio as Echolink on a computer (or cellphone) and I think many of us
> would be quite scathing of someone who claimed he made a ham radio
> contact because he called someone up on Echolink.

A lot of people seem to forget that the original intent of EchoLink was to 
interconnect RADIOs in different  regions together over the Internet.

Several years ago, I saw a posting somwhere reporting that the author of 
EchoLink now regretted implementing the local-user-in 
front-of-PC-mike-&-speaker mode of EchoLink rather than keeping it strictly a 
radio-to-radio setup like IRLP.   Providing the local user mode reduced 
EchoLink to being essentially a hams-only version of Skype or Google Voice.



Stephen H. Smith    wa8lmf (at) aol.com
EchoLink Node:      WA8LMF  or 14400    [Think bottom of the 2M band]
Skype:        WA8LMF
Home Page:          http://wa8lmf.net

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