Digital signal transmission through antenna

[Baranidaran]

Why can't we transmit digital signals through antenna? All the antennae receives and ditributes analog signals only.

Anyone can help me understand the logic behind it?

 

[putturvenkatesh]

Why can't we transmit digital signals through antenna? All the antennae receives and ditributes analog signals only.

Anyone can help me understand the logic behind it?

Digital signals are two levels of voltages. Where as to transmit through antenna, you need something which is continuously changing.

Look for a book with antenna theory basics. You will get answer for your question.

 

[jiripolivka]

To transmit a digital signal by electromagnetic waves ( transmitting antenna, free space, receiving antenna) you need a transmitter in which your digital signal modulates a RF (radio frequency) carrier. The RF spectrum so generated can then be transmitted to a remote receiver. In the receiver, the RF spectrum is demodulated to obtain your digital signal back.

The process has many interesting features. Typically, transmission process adds noise and distortion; this affects BER, bit-error-rate, a parameter used to quantify how successfully the output digital signal copies the input.

 

[halee awan]

Yep Digital signal can be transmitted if you used one of the Digital modulation technique
see the image below

also visit thislink in order to get better understanding .
**broken link removed**

If you put more concentration you will find in actual analog transmission is only possible:smile:
further more according to Fourier ,square wave /Digital signal
contain infinite # of Harmoins of Fundamental frequency.

and I think you are confiusing yourself in this case

 

[elecstudward]

Hi all, i have read so much about digital modulation M-QAM, where bits are converted to symbols and sent through the channels. But i am not clear on the transmission of the 'symbols' itself, for example from the bock diagram below, the streams are modulated by sin n cos signal and then sent through channels, what's the role of the symbol in this case?

Thank you

 

[betwixt]

Is that diagram correct?
Should the "2-bit anaolog to digital" be "digital to analog" ?

Brian.

 

[elecstudward]

oh yeah, its should be to analog, but anyway, how does constellation map (with complex numbers) represent this process in the block diagram?

 

[davenn]

Why can't we transmit digital signals through antenna? All the antennae receives and ditributes analog signals only.

Anyone can help me understand the logic behind it?

there is no logic cuz your statement is in error. Digital signals are transmitted through antennas all day every day.... mobile phones, digital TV to name a couple.

so maybe you had better clarify what you are trying to achieve and why you think you cant transmit a digital signal through an antenna

cheers
Dave

 

[vinoth8051]

Hi Baranidaran,
To understand this easily, we have to think in frequency domain.
Assume we are having 100khz sine wave ---- in frequency domain you will get one single peak at 100khz. one antenna is enough to transmit this signal.
But take the square wave of same frequency ---- in frequency domain, it has number of values.
So to transmit digital signals your antenna has to resonate at wide range of frequencies to faithfully reconstruct the signals.
This is due to the fact that " square wave is made up of continuously changing sine and cosine wave forms".



Researches are going on Ultra wide band antennas to help in transmission of pulses and digital signals
Hope this helps...