RF Front Ends

That thing that goes between the antenna and the mic input

The RF front end is the device that goes between the receiving antenna and the audio input (microphone input) of your Apple device or stereo microphone adapter. The RF front end is what determines which radio frequencies you will be able to listen to. iSDR is able to provide up to 44 kHz of usable bandwidth centered at the RF front end’s center frequency. Note that iSDR provides a menu setting that allows you to set the displayed center frequency to agree with that of your RF front end hardware.
For those unfamiliar with the concept of Software Defined Radio and the role of the RF front end, this wikipedia article provides some background.

 

Warning: Users connecting non-Apple hardware to their Apple devices do so at their own risk. Neither Apple nor the application developer is liable for any damage resulting from such use. Read and understand all product warranty statements before deciding whether to use your electronic devices for SDR activities.

Today there is no commercial RF front end hardware designed for use with Apple iOS products. Hopefully someday that will change. But for now, software-defined radio on Apple iOS products is totally experimental, and requires some care and ingenuity to put in place. The manufacturer’s warrantee for your Apple device will not cover any damage resulting from attaching an unapproved electronic device to your iPhone, iPad or iPod!

The overall performance of your radio setup will depend largely on the type and installation of the receiving antenna you use, and the performance characteristics of the RF front end.

iSDR should work with any RF front end that meets the following requirements:

1. Provides in-phase and quadrature (I&Q) baseband audio output signals.
2. Provides an output impedance compatible with the Apple product’s microphone input.
3. Provides output signal levels that are compatible with the Apple product’s microphone input.

QSD-type RF front end devices range widely in price. The least expensive are simple kits that can be hand assembled using appropriate tools for surface mount components.

Below are some of the options for those looking for an RF front end device. Please contact the manufacturers of these devices with any questions regarding using their devices with Apple products and iSDR.

Tony Parks, KB9YIG: SoftRock40 (May be discontinued soon!)

Multus SDR LLC: Multus

Lazy Dog Engineering: LD-1A/B

Elektor: Elektor Software Defined Radio

MOBOKits: MOBOKits

Genesis Radio: Genesis Radio Software Defined Radio Kits

Kazunori Miura, JA7TDO: http://zao.jp/radio/66lite/

FlexRadio: FlexRadio Systems

Chris Moulding, G4HYG: http://www.crosscountrywireless.net/sdr_receiver.htm

Phil Covington: http://www.srl-llc.com/

Device specifications can change, so please contact the manufacturers to confirm their products’ suitability for use with iSDR. Experimenters who try any of these (or other) devices with iSDR are encouraged to report their findings with a reply to this thread.

Special Note:
FUNcube: http://www.funcubedongle.com – Due to a lack of required drivers, and USB current limitations, iOS devices are not compatible with USB SDR devices such as the FUNcube.