Hi. In need some hacker expertise...
Am after guidance to learn how to modify a digital FM receiver module from its normal state of 88-108MHz into a 118-138MHz. Demodulation AM/FM/data irrelevant. No old transistor radios. Candidates like:

----> https://www.aliexpress.com/item/FM-...4.0&pvid=42c5a4a5-be16-4814-a490-47bbd60a307b

----> https://www.aliexpress.com/item/FM-...91-486a-87be-c86ccea7e328&transAbTest=ae803_5

Or similar on ~3V DC modules/breakboards, Or if there is such module for the wanted band that you may know, please advise.

 

This is a totally unqualified reply but there are a large number of chips out there for SDR's that do similar. You may want to spring for one that dose the same signal conversion for them. It may help you glean an idea of what your end hack will look like.

 

Thanks. If anyone knows a non-volatile-software-defined-radio front-end chip that can display the tuned frequency and keep it memorized after power cycling, that may be useable.

The USB SDR sticks that do it only work that way if kept plugged to an active USB port as I understood exploring that option.
What are the mysteries of shifting the local oscillator to a module as the linked ones ? May receive but unable to display the frequency properly ? Or using a different crystal than the installed ?
It is to be used outdoors 24/365 after programmed, running on solar panel, no computers involved.

 

A properly configured and filtered 30 MHz oscillator at the antenna input, will convert a bandpass of 118-138 to 88-108 MHz.

They use to call them frequency up/down converters.

 

The 118MHz to 137MHz radio frequencies band is used for aircraft communications. An FM receiver will not work because the modulation is AM so that an airplane is distress can break into another communication (FM has a capture ratio that does not allow breakins).
Also an FM stereo receiver has a very wideband pickup but the aircraft communications are narrowband.

 

"Demodulation AM/FM/data irrelevant."