Making radio without the radio module

Hello, I want to build a radio that I'll be able to tune to local radio stations and listen to them. I have already constructed an antenna (simply connecting a metal spiral to an analog pin) and then I connected a speaker to the arduino board and programmed it to play a certain tune according to the reading from the antenna. Here is the code I used:

const int speaker = 8;
const int antenna = A0;

void setup() {

  pinMode(speaker, OUTPUT);
  pinMode(antenna, INPUT);

}

void loop() {

  double input = analogRead(antenna);
  PlaySound(input);

}

void PlaySound(int num) {
  digitalWrite(speaker, HIGH);
  delayMicroseconds(num);
  digitalWrite(speaker, LOW);
  delayMicroseconds(num);
}

It kinda worked, it just played white noise as I expected obviously I wasn't able to hear any radio station because I couldn't tune that because I was missing the radio module, but anything that is done at the radio module can be done with the arduino and maybe a couple of basic electronic components. So does anybody know what can I change in order to make the makeshift radio tuneable?

but anything that is done at the radio module can be done with the arduino

No! What makes you think that?

What radio frequencies do you want to listen to? Long wave, Medium wave, Short wave, VHF, UHF?

Make a crystal radio instead.

Grumpy_Mike: No! What makes you think that?

What radio frequencies do you want to listen to? Long wave, Medium wave, Short wave, VHF, UHF?

I didn't say that it can be done only with the arduino, of curse you need some capacitors, resistors, diodes and of curse the antenna. All those things I already have, I just think that using the arduino it could be a lot easier. And by the way, I wish to listen to VHF frequency band

Here is a Wikipedia article about [u]how radios work[/u]. You should also probably study-up on AM and/or FM demodulation.

The tricky parts are tuning the filters and the local oscillator. It’s usually going to require an at-least an oscilloscope and it would also me nice to have a frequency counter. Manufacturers use expensive specialized test equipment.

I just think that using the arduino it could be a lot easier.

Sadly, no.

dindibo4: I didn't say that it can be done only with the arduino, of curse you need some capacitors, resistors, diodes and of curse the antenna.

And some transistors and some crystals and some transformers, in fact all the parts that go to make a radio module, leaving absolutely nothing for an Arduino to do. You might as well throw it away.

And by the way, I wish to listen to VHF frequency band

That makes it even more difficult to do it with your components as you also need a proper PCB.

What has the antenna done to you so that you feel the need to curse it?

Is this post linked to the "how to boost a voltage without a voltage booster" that we just had? Seems to be a them.

Ok, I get it it’s not as simple as I thought it is.
Thanks for the answers.

Actually, if you care about AM and not FM, it can be quite simple. All you need is a coiled antenna with taps, a diode for a half wave rectifier, a capacitor and resistor for an envelope detector, an earpiece, and a battery. I once made a radio receiver with these components (they came in a kit) and it worked like a charm; really simple AM receiver.

Power_Broker: Actually, if you care about AM and not FM, it can be quite simple.

However VHF was specified, it is almost entirely FM except for aviation band. It is not impossible: http://www.crystal-radio.eu/enset6.htm

aarg:
However VHF was specified, it is almost entirely FM except for aviation band. It is not impossible:
Crystal receiver for the FM band.

True (I didn’t see the note), but maybe OP would be interested in changing his/her requirement.

aarg writes the following:

However VHF was specified, it is almost entirely FM except for aviation band.

There is of course apart from FM, SSB (single sideband) and quite a few digital modes.

What the OP needs to specify is what band or frequency is of interest and what is the modulation used for the particular station. As Grumpy says, careful attention to PCB layout and components will be important at higher frequencies.

Specifically, what is the point of this project, to hear the original modulated signal or to use it to drive some pseudo tone or signal generation ?


Paul - VK7KPA

rockwallaby: aarg writes the following: There is of course apart from FM, SSB (single sideband) and quite a few digital modes.

I'm speaking statistically. If you scan around in most countries, FM has the lions share of the traffic. It's worth mentioning the software defined receivers: http://www.qsl.net/py4zbz/hfrtl.htm https://www.rtl-sdr.com/buy-rtl-sdr-dvb-t-dongles/

Disclaimer: I haven't tried these. Yet.

aarg: https://www.rtl-sdr.com/buy-rtl-sdr-dvb-t-dongles/

The RTLs are not the mose sensitive of devices, but within the frequency range (24 – 1766 MHz) they are very good value.

Very useful as a scanner for anyone working with ISM band radio modules, measuring realtive power levels, checking harmonics etc.

With a reasonable LNA in front of them they are good enough for minitoring amateur radio satellites etc.