Many modern amateur radio transceivers provide easy access to the Intermediate Frequency (IF) signal, or In-phase/Quadrature (I/Q) signals, generated by the radios internally. Using either IF or I/Q it is possible to utilize your Apple device running iSDR to function as a touchscreen color-display panadapter!
A panadapter is a device that allows you to see the RF spectrum being received by a radio receiver. There are commercial (often expensive) panadapters available, but if you already own an Apple iOS device then iSDR can provide you with a less expensive and more flexible option.
Panadapter Using I/Q
Using iSDR as a panadapter by direct access to buffered I/Q signals was first accomplished with a commercial radio product using the Elecraft KX3 transceiver. The process is relatively simple and is illustrated in the simplified diagram below.
NOTE: Be sure to consult the radio manufacturer’s documentation to determine whether external I/Q signal access is provided, and how to properly access it.
Panadapter Using IF
In rigs that do not provide I/Q signal access it might be feasible to implement a panadapter using the IF signal. Some modern radios provide access to a buffered IF signal that can be readily used as illustrated in the diagram below. You will notice in the diagram that it is necessary to add a direct-sampling RF detector (with its sampling frequency set at or near the IF frequency) to convert the IF signal to I/Q baseband signals that can be demodulated and displayed by iSDR.
NOTE: Be sure to consult the radio manufacturer’s documentation to determine whether external IF signal access is provided, and how to properly access it.
