# Arbitrary ADC resolution at the receiver **URL:** \ **Category:** GNU Radio\ **Created:** [June 30, 2014, 4:38pm UTC](https://www.ruby-forum.com/t/arbitrary-adc-resolution-at-the-receiver/230706 "2014-06-30T16:38:45Z")\ **Posts on this page:** 7\ **Page:** 1
**Author:** ![addis\_a](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/c4cdca/32.png) [@addis\_a](https://www.ruby-forum.com/u/addis_a)\ **Post date:** [June 30, 2014, 4:38pm UTC](https://www.ruby-forum.com/t/arbitrary-adc-resolution-at-the-receiver/230706/1 "2014-06-30T16:38:45Z")
Hello everyone, I excuse myself on advance by my noob question… I have an N210 with an SBX front end, and I want to experiment with decoding signals at a lower resolution, rather than the default 12 bits provided by the N210 ADCs. Does anyone know if (and how) can I limit the resolution of the ADCs arbitrarily? I am aware that I can reduce the resolution afterwards, mapping the signals to a lower resolution in base band, but I’d really like to do that before the DDC at the FPGA. Cheers to everyone! Leonardo S. Cardoso removed\_email\_address@domain.invalid ---
**Author:** ![leonardocg](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/l/e274bd/32.png) [@leonardocg](https://www.ruby-forum.com/u/leonardocg)\ **Post date:** [June 30, 2014, 4:45pm UTC](https://www.ruby-forum.com/t/arbitrary-adc-resolution-at-the-receiver/230706/2 "2014-06-30T16:45:19Z")
* * * Discuss-gnuradio mailing list removed\_email\_address@domain.invalid [https://lists.gnu.org/mailman/listinfo/discuss-gnuradio](https://lists.gnu.org/mailman/listinfo/discuss-gnuradio) ---
**Author:** ![leonardocg](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/l/e274bd/32.png) [@leonardocg](https://www.ruby-forum.com/u/leonardocg)\ **Post date:** [June 30, 2014, 4:47pm UTC](https://www.ruby-forum.com/t/arbitrary-adc-resolution-at-the-receiver/230706/3 "2014-06-30T16:47:42Z")
The n200 and n210 have 14 bit ADCs. In any case, you can fake fewer bits by zeroing the low order bits in the fpga. Matt ---
**Author:** ![leonardocg](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/l/e274bd/32.png) [@leonardocg](https://www.ruby-forum.com/u/leonardocg)\ **Post date:** [June 30, 2014, 5:01pm UTC](https://www.ruby-forum.com/t/arbitrary-adc-resolution-at-the-receiver/230706/4 "2014-06-30T17:01:25Z")
Yes, 14 bits… mistyped the ADC resolution… Thanks, Matt. I’ll investigate this idea… Leonardo S. Cardoso removed\_email\_address@domain.invalid ---
**Author:** ![leonardocg](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/l/e274bd/32.png) [@leonardocg](https://www.ruby-forum.com/u/leonardocg)\ **Post date:** [July 1, 2014, 2:55pm UTC](https://www.ruby-forum.com/t/arbitrary-adc-resolution-at-the-receiver/230706/5 "2014-07-01T14:55:52Z")
Hi Marcus, There are several reasons why we would like to avoid reducing the resolution in software: 1. Reduce receiver complexity; 2. Capture any artifact of the DDC with respect to the reduction of the resolution. Frankly speaking, I’m not sure any of these arguments are defendable to impose a resolution control at the ADC or even the ADC-FPGA interface. If it isn’t, then I agree it is much simple to do it in soft. BR, Leo Leonardo S. Cardoso removed\_email\_address@domain.invalid On Mon, Jun 30, 2014 at 5:46 PM, Marcus Müller [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) ---
**Author:** ![leonardocg](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/l/e274bd/32.png) [@leonardocg](https://www.ruby-forum.com/u/leonardocg)\ **Post date:** [July 1, 2014, 3:42pm UTC](https://www.ruby-forum.com/t/arbitrary-adc-resolution-at-the-receiver/230706/6 "2014-07-01T15:42:56Z")
Hi Leo, well, I’d argue that reducing receiver complexity doesn’t really happen when you start changing the FPGA with respect to dev effort; I can see your DDC numerical accuracy point, though. However, how would reducing the ADC resolution make artifacts more noticable? As you get ca -6dB theoretical SNR with each bit you cut at the ADC, errors in the DDC should become less relevant, not more. Best Regards, Marcus ---
**Author:** ![leonardocg](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/l/e274bd/32.png) [@leonardocg](https://www.ruby-forum.com/u/leonardocg)\ **Post date:** [June 30, 2014, 5:47pm UTC](https://www.ruby-forum.com/t/arbitrary-adc-resolution-at-the-receiver/230706/7 "2014-06-30T17:47:54Z")
Just out of curiosity: Why would you want to reduce the ADC resolution? Most of the effects introduced can be simulated in GNU Radio, e.g. by converting a float stream to integer and dividing it by a constant power of two. Greetings, Marcus