The whole sequence is:
- Digitally synthesized spectrogram (lossless)
- Played through a DAC and speaker to produce an analogue signal (lossy)
- Heard by the bird (analogue, lossy)
- Reproduced by the bird (analogue, lossy)
- Captured by an ADC as a digital audio signal (lossy)
- Spectrum-analysed to observe a similar (but corrupted) reproduction of the shape in the PNG
To be transferring digital information, we would instead need to modulate and demodulate the digital signal (exactly like an old modem) so that the analogue corruption does not affect the digital signal:
- Image file (lossless)
- Bit stream (lossless)
- Analogue modulation of bit stream played through DAC (lossy)
- Heard by the bird (lossy)
- Reproduced by the bird (lossy)
- Demodulated to recover exact bit stream despite distortion (lossless,)
- Decode bit stream to recover original image file, bit-for-bit perfect
I extremely doubt that this bird is capable of 2MB/s. For reference that would make it 280+ times fast than dialup, and barely slower than ADSL. This setup is basically just using the bird instead of a telephone line.
CookieOfFortune@lemmy.world 3 days ago
These steps are literally the same thing. You’re converting some data into sound for the bird to hear.
gozz@lemmy.world 3 days ago
Yes, the near-identical sentences (only drawing a distinction between the processes where one exists) would indicate that. The “heard by the bird” and “reproduced by the bird” steps were also the same. But this is necessary context to make clear the digital data (“bit-stream”) that is being modulated into the signal.
It is far from “exactly the same”. The similarity is only in that both go through the same analogue channel. The entire point is that the modulated signal can be reconstructed exactly, while the spectrogram cannot.
CookieOfFortune@lemmy.world 3 days ago
But this isn’t true. Just because a signal is modulated doesn’t mean it can’t be distorted.
A spectrogram is just showing that arbitrary data can be sent though this channel. It’s literally a form of modulation.
gozz@lemmy.world 2 days ago
I suppose you have caught me out slightly lacking in precision or pedantry. A digital to analogue modulation scheme is able to exactly reconstruct the original digital signal within the design tolerances for noise and distortion. Yes, eventually a signal may degrade or be corrupted, but prior to that point the reproduction is literally and exactly perfect. That exactitude is just about the definition of a digital system. This bird system is incapable of reproducing the input image of the bird exactly. It is not a digital communication system, unless you consider the “PNG” of the bird to have not been the message being carried.