Timeline for Which noise sources dominate in a receiver?
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| May 16, 2022 at 15:36 | comment | added | user1850479 | The link you posted gives a good example. That ADC is a $100 in bulk (so fairly expensive), but of the 14 bits it specs less than 12 actually contain useable information at 105 MHz, so already at those frequencies you can see how ADCs are becoming expensive while quantization noise is creeping up. 20 MHz will be better, but your budget and specifications are going to determine what actually limits you. Below 1 MHz things are different, you'll rarely if ever be limited by the ADC at audio frequencies for example because you can get 18 or 20 bits for almost nothing. | |
| May 16, 2022 at 15:08 | comment | added | Gillespie | Thanks @user1850479. By low frequencies I assume you are referring to the bandwidth/sampling rate, not the carrier. I know there's no exact answer, but do you have a sense for roughly which BWs are "low or moderate?" Would 20 MHz be considered low to moderate? | |
| May 16, 2022 at 14:59 | comment | added | user1850479 | That is a reasonable generalization for low to moderate frequencies where it is easy to make ADCs with high ENOB, but especially at higher sampling rates it can get quite hard to keep quantization noise 10dB below the noise floor. This is why digital cameras you still have an ISO (gain) setting that lets you adjust how much gain you provide to the ADC. This exists specifically because sensor dynamic range is higher than the ADC dynamic range, so the user may need to adjust the gain for bright or dim photography conditions to manage quantization noise. | |
| S May 16, 2022 at 13:53 | review | First answers | |||
| May 16, 2022 at 13:58 | |||||
| S May 16, 2022 at 13:53 | history | answered | Gillespie | CC BY-SA 4.0 |