[Ccarc] Cellphone -Ham radio connect

[Tom Murray]

Cellphones in Service to Amateur Radio

		
                
                
                       
                            Kenneth M. Beck (WI7B)
                       
                
		on
		December 22, 2007
		
		    
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There is a new-type cellphone available. It includes not only
implementation of Windows Mobile 6.0 or equivalent advanced Pocket PC
operating systems, but also a chipset that includes both GPS protocols,
and A-GPS protocols (cellular/satellite fast fix coordination). 



 


An example is the AT&T Tilt (HTC TyTN II-Kaiser), pictured in
Figure 1. This phone is also available from other providers, different
cellular protocols (e.g., Sprint on CDMA) and under different names.
Packing a Qualcomm 400 MHz CPU with over 100 MB of RAM, the phone has
the capability to access up to 32 GB of data via microSDHC (super high
density media cards). This phone could have been purchased at AT&T
stores for as little as $149 during Thanksgiving. It is a complete,
networked mobile PC if purchased with a data plan. It has Bluetooth
(BT) connectivity, and a specialty mini-USB port. Implemented at
AT&T, it is EDGE/3G capable with up to seven frequency bands for
operation in almost any country in the world.




 








 


FIGURE1




 


So, what does this have to do with ham radio? 




 

The
Tilt has the ability to run such programs as PocketDigi, a mobile
digital mode program that includes PSK-31/RTTY/CW send and receive.
Figure 2 shows an example of the PocketDigi in operation on 40m
receiving a CQ de WA6OVP (The Tilt's front screen opens to expose its
keyboard). To connect the cellphone to the HF transceiver's audio, I
used a BT headset that formerly made hands-free cellular calls. A quick
removal of the headset's microphone and speaker, a few careful solder
joints, and an isolation BT interface for PSK31 is born.




 








 


FIGURE 2




 

For
me, the internal GPS was of greatest interest. It could be used for
APRS. As an active ham when I travel I am often confronted with MANY
electronic devices to pack. The fewer devices needed the better. Having
ham digital modes available in my cellphone is a great asset. Having a
GPS unit in my cellphone is a boon. 



 


How to access the GPS chipset in the phone for APRS? 




 


I have been able to implement NMEA data flow from my cellphone internal
GPS using the following procedure. It should also work with the
SiRFstar III chipset in similar cellphones equipped with BT. I use a
Kenwood TH-D7(G), an HT that has a built-in TNC for packet or APRS. The
Kenwood HT successfully transmits the GPS coordinates to the APRS
network (in the US on 144.390 MHz). 



 


The connectivity between the cellphone and TH-D7(G) was accomplished by
using a Brainboxes' BL-830 female DB-9-to-Bluetooth adapter attached to
a DB-9-to-3 conductor 2.5mm plug going to the Kenwood's GPS receptacle,
as pictured in Figure 3. 



 








 


FIGURE 3




 


On the AT&T Tilt, I use the client software from GPSGate.com for
PocketPC ($19.95) to set up a connection between the output of the
internal GPS on COM4 and the cellphone's Bluetooth Server. An added
bonus of this process is that one can place the HT for best
transmission in one location and independently place the wireless GPS
at another location within the 10m range of the BT units.




 

In
Figure 4, you see the AT&T Tilt plotting my car's position (the
Jogger icon) on Google Maps as I drive, along with a nearby APRS
weather station. The camera was a little shaky, hi hi. 



 








 


FIGURE 4




 


I'm continuing to work on this process with the hope that waypoint data
from the Kenwood HT (APRS Stations) can be passed to the AT&T Tilt
so other GPS mapping programs (e.g., Garmin Mobile XT) will work
without the need for external access to the cellular phone network.




 


---* Ken WI7B 

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