# OOK modulation naming

**URL:** <https://www.ruby-forum.com/t/ook-modulation-naming/241392>\
**Category:** GNU Radio\
**Created:** [April 2, 2015, 8:18pm UTC](https://www.ruby-forum.com/t/ook-modulation-naming/241392 "2015-04-02T20:18:33Z")\
**Posts on this page:** 6\
**Page:** 1

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**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:** [April 2, 2015, 8:18pm UTC](https://www.ruby-forum.com/t/ook-modulation-naming/241392/1 "2015-04-02T20:18:33Z")

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A friend recently showed me an OOK modulation that I had never seen  
before, and I’m wondering if anyone knows a name for this scheme.

It is PWM where both the on periods and off periods carry data in their  
durations.

In the example we observed, an on or off period with a duration of two  
units represents a zero. An on or off period with a duration of one  
unit represents a one. Example:

–_-_–\_--\_\_-

This sequence of amplitudes represents the binary data 011101001.

Note that this scheme has a variable data rate. (Two packets carrying  
the same number of bits may have different durations.) Overall,  
however, the data rate is higher than in a similar looking scheme in  
which data are encoded only in the on periods.

Does anyone know what to call this? I am tempted to call it Biphase  
PWM.

Thanks,

Mike

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**Author:** ![m1ke0](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/m/85f322/32.png) [@m1ke0](https://www.ruby-forum.com/u/m1ke0)\
**Post date:** [April 2, 2015, 8:45pm UTC](https://www.ruby-forum.com/t/ook-modulation-naming/241392/2 "2015-04-02T20:45:15Z")

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Why not make the ratio 1:3 and then you could call it Morse PWM. 🙂

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**Author:** ![m1ke0](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/m/85f322/32.png) [@m1ke0](https://www.ruby-forum.com/u/m1ke0)\
**Post date:** [April 2, 2015, 9:25pm UTC](https://www.ruby-forum.com/t/ook-modulation-naming/241392/3 "2015-04-02T21:25:12Z")

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Hey Mike,

I think that NRZI.

- Jeff

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**Author:** ![m1ke0](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/m/85f322/32.png) [@m1ke0](https://www.ruby-forum.com/u/m1ke0)\
**Post date:** [April 2, 2015, 9:30pm UTC](https://www.ruby-forum.com/t/ook-modulation-naming/241392/4 "2015-04-02T21:30:32Z")

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I though NRZI had a constant symbol rate. I would expect 011101001 in  
NRZI to look like:

_-_–\_\_\_-

Mike

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**Author:** ![m1ke0](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/m/85f322/32.png) [@m1ke0](https://www.ruby-forum.com/u/m1ke0)\
**Post date:** [April 3, 2015, 3:16pm UTC](https://www.ruby-forum.com/t/ook-modulation-naming/241392/5 "2015-04-03T15:16:33Z")

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Great find, Jeff! I’m also finding it called “Digital Pulse Interval  
and Width Modulation” with the same acronym. I think it is clearer with  
the “and” in there, and that version of the name dates back at least to  
1995.

Mike

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<div class="post-metadata">

**Author:** ![m1ke0](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/m/85f322/32.png) [@m1ke0](https://www.ruby-forum.com/u/m1ke0)\
**Post date:** [April 2, 2015, 10:25pm UTC](https://www.ruby-forum.com/t/ook-modulation-naming/241392/6 "2015-04-02T22:25:37Z")

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After way to much searching … under Anisochronous modulation, there is  
something called Digital Pulse Interval Width Modulation (DPIWM).

> **[thesis010.pdf](https://www.paradise.caltech.edu/papers/thesis010.pdf)**
>
> 2.18 MB

Seems like as good a name as any.

- Jeff