The Talky GPS transponder uses a dra818U radio module. Unfortunately, this module transmits harmonics at higher frequencies, interfering with other electronics. Now that the Talky GPS transponder is equipped with a low-pass filter, this problem is solved. This now allows the GPS SMS transponder to work within the vicinity of the Talky GPS.
The GPS SMS transponder transmits coordinates at a 2 minute interval at ground level. When launched, the GPS SMS transponder transmits every 30 seconds.