[aprssig] APRSpro iOS app
Stephen H. Smith
wa8lmf2 at aol.com
Wed Apr 6 14:02:21 EDT 2016
On 4/6/2016 11:25 AM, brashears--- via aprssig wrote:
> 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
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:
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
EchoLink: Node # 14400 [Think bottom of the 2-meter band]
Home Page: http://wa8lmf.net
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