Why do digital radios use far more electricity then analogue? Thanking you?

Answer 1

If some digital radios consume more electrical energy than their analogue counterparts, it could be due to higher switching losses in the digital electronic circuits. This excess consumption can be greatly reduced by connecting a 100nF ceramic or plastic film capactor in parallel with the the supply terminals of the integrated circuits on the PCB.

Answer 2

Because... they don't. At least not in general.

Your cell phone is a mostly digital radio. So is your wireless network card but they can work on a few 100mW. Many of the signal processing functions used in these radios would be almost impossible to implement in an analog fashion. Even if they could be, they would almost always come at a greater power consumption than their digital equivalent.

The physical reason is very simple: the signal to noise ratio of a digital representation is a linear function of the power consumption: every bit adds 6dB. In the analog world, you have to double the voltage to get 6dB more, which is quadrupling the power demand!

And if we are talking about multipliers, the ratio gets even worse. A 1GHz bandwidth analog multiplier will cost something like 1W (if you use a diode mixer, the LO level will kill you, in a Gilbert cell it is the bias current to get reasonably low noise). The same thing in a modern 16bit CMOS process is probably not much more than 10mW.

I worked with an engineer once who had worked on a synthetic aperture radar to detect and identify the type of an aircraft from a distance. His partly analog "machine" was the size of a small car and they had to install another small gas turbine on the plane carrying it, just to power it. Today, I could probably put the same algorithm into a battery operated device and it would work just fine.

Answer 3

I'd Like to know how you are sure of this.I was a bit surprised how quickly a set of batteries ran down with the digital radio so I was going to connect a power supply to the radio via croc clips and a multimeter first to the digi-set then to the analogue set,problem is getting volumes equal.Interseting though.

Answer 4

A crystal radio requires zero dc power. It is powered from the radio station itself! You can't beat that.

Analog circuits are simpler. LC and ceramic filters consume zero power.

Digital filters are made of registers, multipliers, logic, clock drivers, etc. This stuff consumes power proportional to clocking rate. If the digital radio has to process a wide bandwidth, then power goes up directly proportional to the bandwidth, due to Nyquist theorem.

Analog circuits that are non-sampled, rely of passive filters that typically require zero power to operate.

Answer 5

than


there's no inherent reason

only that analogue radios have been around longer and
over the years designs have had battery life as a parameter

where do you get such an assertive viewpoint I wonder

Answer 6

Digital radios require a far more complex circuit design that can employ the equivalent of thousands of transistors, each chewing a tiny amount of power, which when added up equals far more power than a conventional non digital signal receiver.

Answer 7

Anything 'digital' needs more power to function, due to the fact that the signal needs to be decoded to be of any use to us.

Answer 8

They do? That's news to me.

Doug