# FOSDEM attendee? Re: 802.15.4 CSS PHY **URL:** \ **Category:** GNU Radio\ **Created:** [February 2, 2015, 7:53am UTC](https://www.ruby-forum.com/t/fosdem-attendee-re-802-15-4-css-phy/234040 "2015-02-02T07:53:27Z")\ **Posts on this page:** 5\ **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:** [February 2, 2015, 7:53am UTC](https://www.ruby-forum.com/t/fosdem-attendee-re-802-15-4-css-phy/234040/1 "2015-02-02T07:53:27Z")
Hi list, this is just a shot in the dark, but I forgot to get the name of an attendee during the Internet of #allthethings talk. If you are, or know who is, the person who said he had implemented an 802.15.4 CSS PHY in the question period, please get in touch with me or pass on the message. It would be very beneficial to collect the 15.4 related work into one repository to reuse some amount of code. The 800 & 900 MHz PHY would be very useful to have in there and would be relatively painless to design. The CSS PHY is obviously much more interesting 🙂 Also, in particular, any future UWB PHY designers would be helpful. The SDR hardware for such a PHY might be a bit pricey. Even a unit-test driven PHY design would be helpful or simulation. As of this point, I have not heard of any major silicon vendors are even speaking about offering an UWB PHY, so it would be nice to be ahead of the game. Cheers, C ---
**Author:** ![christophrost](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/c/a3d4f5/32.png) [@christophrost](https://www.ruby-forum.com/u/christophrost)\ **Post date:** [February 2, 2015, 3:41pm UTC](https://www.ruby-forum.com/t/fosdem-attendee-re-802-15-4-css-phy/234040/2 "2015-02-02T15:41:24Z")
Hi, that was me ;). I also talked to Bastian B. and we agreed that I will create a pull request to gr-ieee802-15-4 once I finish my master’s thesis and have it all cleaned up. In the meantime, you can find my fork of Bastian’s repo here: [GitHub - fwunsch/gr-ieee802-15-4: An IEEE 802.15.4 ZigBee Transceiver.](https://github.com/fewu/gr-ieee802-15-4). The branch with my work is called css\_phy. Currently I’m working on the synchronization for the CSS PHY. My previous work focused on evaluating PHY and MAC performance with the assumption of perfect sync. It’s also not really complete yet (e.g. preamble and PHR are dropped in the receiver because their content is assumed to be known) and endianness might be wrong at some points. But I will try to fix that in the next weeks. Feel free to contact me if you have any questions! Greetings Felix 2015-02-02 7:52 GMT+01:00 Christopher F. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid): ---
**Author:** ![christophrost](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/c/a3d4f5/32.png) [@christophrost](https://www.ruby-forum.com/u/christophrost)\ **Post date:** [February 2, 2015, 5:03pm UTC](https://www.ruby-forum.com/t/fosdem-attendee-re-802-15-4-css-phy/234040/3 "2015-02-02T17:03:25Z")
Hi Christopher, in your talk you mentioned some bugs that you found. Would be great if you could create some patches and a make pull request. If someone is interested in the 800 MHz phy I will look for cheap HW and try to implement them. Best, Bastian On 2015-02-02 15:39, Felix W. wrote: > receiver because their content is assumed to be known) and endianness > > ``` > repository to reuse some amount of code. The 800 & 900 MHz PHY would > > ``` > > * * * > > 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) – Dipl.-Inform. Bastian B. Distributed Embedded Systems University of Paderborn, Germany > **[Home](https://www.bastibl.net/)** > > I'm Bastian Bloessl, a Research Group Leader at the Secure Mobile Networking Lab, TU Darmstadt. Checkout my blog, projects, publications, and resume; or connect on Github, Twitter, YouTube, or Facebook. ---
**Author:** ![christophrost](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/c/a3d4f5/32.png) [@christophrost](https://www.ruby-forum.com/u/christophrost)\ **Post date:** [February 5, 2015, 2:16pm UTC](https://www.ruby-forum.com/t/fosdem-attendee-re-802-15-4-css-phy/234040/4 "2015-02-05T14:16:06Z")
Excellent! Thanks for your reply Felix! As Thomas R. pointed out, the sync problem would ideally be solved with the correlate and sync block, as 802.15.4 packets have a known preamble and SFD but there might be some glitches with it. However, Thomas also optimized Costas Loop to be quite efficient now (see [1]). I’m doing a bit of experimenting on synchronization for this week and will submit a pull request to Bastian as well. Cheers, C [1] > **[What's the right way to calculate tanh? — Rondeau Research](http://www.trondeau.com/blog/2014/9/1/whats-the-right-way-to-calculate-tanh.html)** > > I'm working on improving the synchronization of M-PSK phase-locked loops, which we call the Costas loop in GNU Radio. I'll post later about what I'm doing and why, but the results are looking very satisfying. However, during this work, I need to... © Sent from my Android ---
**Author:** ![christophrost](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/c/a3d4f5/32.png) [@christophrost](https://www.ruby-forum.com/u/christophrost)\ **Post date:** [February 5, 2015, 3:38pm UTC](https://www.ruby-forum.com/t/fosdem-attendee-re-802-15-4-css-phy/234040/5 "2015-02-05T15:38:30Z")
Will do! © Sent from my Android