# Fwd: Question Concerning Custom Modulator Block **URL:** \ **Category:** GNU Radio\ **Created:** [February 20, 2014, 1:50pm UTC](https://www.ruby-forum.com/t/fwd-question-concerning-custom-modulator-block/239284 "2014-02-20T13:50:35Z")\ **Posts on this page:** 3\ **Page:** 1
**Author:** ![musicdenotation](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/m/ea666f/32.png) [@musicdenotation](https://www.ruby-forum.com/u/musicdenotation)\ **Post date:** [February 20, 2014, 1:50pm UTC](https://www.ruby-forum.com/t/fwd-question-concerning-custom-modulator-block/239284/1 "2014-02-20T13:50:35Z")
Forgot to hit reply all. On Wed, Feb 19, 2014 at 3:30 AM, Martin B. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid)wrote: > 800 items (samples). > > > Do I make sure noutput\_items is equal to number of samples I wish to > > I am going to feed directly to the USRP sink, so a vector output is not > > shaping filter. > > M > > * * * > > Discuss-gnuradio mailing list > removed\_email\_address@domain.invalid > [Discuss-gnuradio Info Page](https://lists.gnu.org/mailman/listinfo/discuss-gnuradio) Both sampling rate and symbol rate is variable, at least I intend it to be. The figurative “N” is calculated at runtime inside general\_work() because it is related to the sampling rate. N is representative of the number samples that the modulator produces. Any code I have written takes place inside the general\_work() routine. The 800 samples that make up the waveform is just an arbitrary number I came up with as an example to explain how many samples I have to get out. In my modulator code, my basis functions will generate the same amount of samples as the samples of the bit stream. For prototyping purposes in MATLAB, I had a 100 samples per each bit of the input. So an input of 8 bits after processing was going to give out 800 samples. In my block code this will be controlled by a variable argument. I know the I/O signature would control that part. So noutput\_items is set in the IO signature, the size of it increases when a vector output is set. So if I call set\_output\_multiple in my constructor and have it set the size of my modulated waveform sample size, will it handle my problem? Is there any block I should look at that has it? ---
**Author:** ![jfaulkenberry](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/c2a13f/32.png) [@jfaulkenberry](https://www.ruby-forum.com/u/jfaulkenberry)\ **Post date:** [February 20, 2014, 8:35pm UTC](https://www.ruby-forum.com/t/fwd-question-concerning-custom-modulator-block/239284/2 "2014-02-20T20:35:32Z")
On 02/20/2014 01:49 PM, Jonathan F. wrote: > I know the I/O signature would control that part. So noutput\_items is > set in the IO signature, the size of it increases when a vector output > is set. So if I call set\_output\_multiple in my constructor and have it > set the size of my modulated waveform sample size, will it handle my > problem? Is there any block I should look at that has it? Perhaps my reply to “Activecat” just know will help. Other than that, I say you just start hacking and see where you end up 🙂 M ---
**Author:** ![jfaulkenberry](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/c2a13f/32.png) [@jfaulkenberry](https://www.ruby-forum.com/u/jfaulkenberry)\ **Post date:** [February 20, 2014, 8:40pm UTC](https://www.ruby-forum.com/t/fwd-question-concerning-custom-modulator-block/239284/3 "2014-02-20T20:40:50Z")
On Thu, Feb 20, 2014 at 2:33 PM, Martin B. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid)wrote: > M > > * * * > > Discuss-gnuradio mailing list > [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) > [Discuss-gnuradio Info Page](https://lists.gnu.org/mailman/listinfo/discuss-gnuradio) Alright, I will take this as my cue to get back to work. I will find that email and take a look. Thanks for the help, I got a lot out of it. Jon