[aprssig] APRSpro iOS app

Stephen H. Smith wa8lmf2 at aol.com
Wed Apr 6 13:02:21 CDT 2016

On 4/6/2016 11:25 AM, brashears--- via aprssig wrote:
> https://www.facebook.com/aprspro/?fref=nf
> Has anyone started testing or using the iOS app for APRS from APRS pro?
> What do you think about it?
> Have you built a cable to connect your iPad or iPhone to your radio or
> are you using the audio modem?
> Jesse Brashear, KJ4LYN
> _______________________________________________
> aprssig mailing list
> aprssig at tapr.org
> http://www.tapr.org/mailman/listinfo/aprssig

Where is this app?   I just searched the App Store and don't see it.

However, I have used "PocketPacket", which despite it's name is a full-blown 
APRS mapping/messaging program with both Internet access and a software TNC 
that uses the sound system.

Like all other iOS APRS apps I have seen on the App store, it is totally 
dependent on on-line mapping services (Open Streets or Google Maps) with no way 
of locally storing maps.  This means it must remain tethered to the Internet 
constantly, making it ill-suited for in-the-field use. Not to mention running 
up huge cellular data usage if you don't have WiFi handy.

[I do have an iOS mapping application, "Pocket Earth", that uses zoomable, 
scalable, VECTOR-based maps from Open Street Maps (not the clumsy fixed-scale 
bitmap "tiles" normally associated with OSM).  You can download and save any 
part of the world that has maps on OSM.  I have the entire US and Canada, at 
street level, stored locally on my iPads and iPod Touch in less than 2GB of 
flash memory. I would LOVE for the author of Pocket Packet and Pocket Earth (no 
connection) to get together, and make these off-line maps available to Pocket 

Dealing with Pocket Packet and similar ham "sound card" apps such as the Black 
Cat Systems SSTV app, one must be aware of four issues:

1)  There is no hardwire option for PTT for these sound card apps since there 
is no serial or parallel port on iGadgets. You must have a soundcard interface 
capable of VOX-like tone-activated PTT keying if you want to transmit on RF. 
The VOX-activated SignalLink USB is a non-starter for these apps, since it 
requires a normal USB port to connect.   However, if you want to provide an 
external source of 9-13 VDC, the classic (non-USB) SignaLink would work.

2)  The 4-contact "TRRS" 3.5mm combined headphone-out/mic-in connector of the 
iDevices (and many other tablets and netbooks) makes the cable assembly to a 
soundcard interface tricky, since you will need to split the TX and RX sides of 
a single cable into separate plugs for the interface IN (TX) and OUT (RX) jacks.

3)  You need to provide DC continuity through about a 5K resistance on the mic 
contact of the TRRS jack to get the iGadget device to mute it's internal mic 
and enable an external mic-in. (The iDevice audio system automatically 
determines if headphones-only, mic-only, line-out or boom-mic headset are 
plugged into the jack. This is based on the presence of short circuits, 
less-than-short-circuits-but-still-conducting, or opens on the various contacts.)

4)  iPads WITHOUT a cellular radio do not have an internal GPS.  You will have 
to use an iOS-compatible external Bluetooth GPS device.  Note that iOS does not 
use standard NMEA.  A GPS device must explicitly support the proprietary iOS 
GPS protocol.   One that I use with my iPad is the Dual XGPS150A described here:
This is a dual-mode device that can work with either iGadgets (I've used it 
with both an iPod Touch and a WiFi-only iPad), and with normal NMEA-aware 
programs (UIview, MapPoint, Precision Mapping, Delorme Street Atlas, etc) on 
Windows tablets and netbooks.

More details on these issues and my self-powered (no batteries or external DC 
required) home-brew tone-activated interfaces is here on my website:
.    <http://WA8LMF.net/ham/tonekeyer.htm>
Finally, a fourth issue that may arise later this year:  There are strong 
rumors that Apple is going to do away with analog-audio mic-in and 
headphone-out on this fall's iDevice introductions.  (The classic analog 3.5mm 
audio jack is the final obstacle to making iDevices even thinner!)

Reportedly you will have to use USB-connected active digital headphones with an 
internal digital-to-analog converter.      This is going to make interfacing 
ham sound card apps to radios much more complex.
Stephen H. Smith    wa8lmf (at) aol.com
Skype:        WA8LMF
EchoLink:  Node #  14400  [Think bottom of the 2-meter band]
Home Page:          http://wa8lmf.net

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