|SpectrumView 0-24kHz displays of waterfall and spectrum|
To make best use of this I need to connect an external audio input into my iPod Touch 4g. A 4-pin jack plug when inserted, rather than a 3-pin one, allows an external audio input (or a mic) to be connected so I can feed my VLF receivers, used for both 8.7-9.1kHz earth-mode comms and for lightbeam baseband/sub-carrier detection, directly into the iPod. Resolution will be down to around 2Hz at best, so this will be of somewhat limited use, but certainly easier than a laptop for quick field tests or quantitative measurements.
UPDATE 16.3.12: to tell the iPod Touch 4g that an external mic is connected you seem to need to have a 4k7 resistor to ground across the terminals. See later post for details.