How to generate a chirp signal from Arduino Due

Hi Everyone,

I am new to Arduino. I just purchase Arduino Due for my research project, since it has two analog output.

I was wondering if it is possible for me to generate a chirp signal as a continuous analog output by Arduino Due? I am trying to use this chirp signal to modulate LED. Any suggestions or advices are highly appreciated!

Thanks

What are you calling a "chirp signal". You want it to sound like a bird? And how is it going to "modulate LED"

Hi, thanks for your reply.

A chirp signal's frequency is changing with time, which could be generated on Matlab. Ideally, the brightness of LED could be modulated according to this changing signal, since the brightness of LED could be linearly related with the applying voltage.

Arduino's "analog outputs" actually are pulse width modulation, that is, the "analog voltage" is in reality the average value of an input that rapidly switches between 0 V and 5 V. The frequency of this switching is generally fixed while the duty cycle, that is, the relative duration of "on" and "off" changes. I've never heard "chirp" used to describe this, rather "chirp" is a time varying frequency.

PWM can be used to vary the intensity of a LED and is in fact one of the basic examples provided with the IDE. Without knowing your application, it's not clear whether is satisfies your particular need. To the human eye, such an LED can be indistinguishable to one driven by a fixed current, but to a faster receiver it looks like a series of pulses.

By "chirp signal " , do you mean this:

from Chirp - Wikipedia

A chirp signal can be generated with analog circuitry via a voltage-controlled oscillator (VCO), and a linearly or exponentially ramping control voltage. It can also be generated digitally by a digital signal processor (DSP) and digital to analog converter (DAC).

The DUE has two 12-bit DACs. It does not have DSP instructions so I don't know how effective it would be at generating a chirp signal.
Why would you want to modulate a LED with it though? If all you want to do is increase and decrease the brightness of the LED, you could do that with a PWM output.

Pete

Perhaps the OP is confusing a certain type of radar with light from a LED. In radar, the chirp is a rapid frequency scan while sending the radar pulse. The reflected signal, return, will contain a pattern of power vs frequency related to the target. All metal edges and gaps in the metal will reflect the radar signal. And based on the length of the metal, will have a specific pattern for a specific target, aircraft, or what ever.

I suppose you could move the frequency up into the visible portion of the spectrum.

Paul

MrMark:
Arduino's "analog outputs" actually are pulse width modulation, that is, the "analog voltage" is in reality the average value of an input that rapidly switches between 0 V and 5 V.

Maybe you missed the bit where they said they were using a Due, before you mistakenly mansplained.