I am working on a project where I need to determine when a radio transmission happens on an air band frequency. I am currently using a handheld radio, with a voltage detection module hooked to the headphone output, I watch for the voltage to go non-zero and that triggers a counter. For each individual transmission, the counter is increased by 1.
Using a handheld radio is an expensive way to do this. It's also pretty kludgy. What I would like is to have some sort of smaller and simpler receiver that I can specify the frequency on, and which could send a high/low or on/off type signal to the arduino, from which I can count the transmissions.
I have not been able to find many options. Any ideas? Thanks!
Frequency bands are allocated for specific purposes. Some bands such as the aviation bands require a license to transmit on that band. So small, cheap transmitters are simply not available. Some bands don't require a license so thousands of people can use them. Those are the bands we usually use for Arduino projects because the transmitters and receivers only cost a buck or less.
The cheap transmitters and receivers are prohibited by law from being easily re-tuned into another band.
Honestly, the handheld radio is the easiest and cheapest way to get a tuneable receiver on the aviation band. With anything else you would be working hard to tune in a specific frequency without picking up any other nearby frequency.
Is there an RX LED on your receiver? Most do have one. It will come on when a signal breaks the squelch circuit. Since you don't want to use your radio, find a scanner that has one. You could monitor it with an LDR or photodiode.
The RPI runs an arm version of Linux , which isnt compatible with PC versions of Linux which use x86 binaries, so pretty unlikley the SDR code will run.
greghughespdx:
Using a handheld radio is an expensive way to do this. It's also pretty kludgy.
On this point, I must disagree. Except that you don't need a transmitter, so a scanner will do. Both of those are specifically designed for good selectivity and sensitivity for the signal you want to receive. Generally a "kludge" is something that is used for a purpose that it was not designed for (among other aspects). Additionally, a scanner has a built in detector and squelch circuit which saves you from having to re-invent it.
mauried:
The RPI runs an arm version of Linux , which isnt compatible with PC versions of Linux which use x86 binaries, so pretty unlikley the SDR code will run.