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David Rowe: Timing Estimation for PSK modems

Thu, 2014-09-18 12:30

Jim, KG4SGP just sent me an email asking about how timing recovery (timing estimation) works in the FDMDV modem. In fdmdv.c, this is performed by the rx_est_timing() function.

At the receiver, we need to “sample” the PSK modem signal at just the right time. A timing estimator looks at the received signal and works out the best time to sample. Timing estimation is a major part of a PSK demodulator. if you get the timing estimate wrong, the scatter diagram looks worse and you get more bit errors.

The basic idea is we pass the modem signal through a non-linearity. The non-linearity could be the absolute function (i.e. a rectifier), a square law, or in analog-land a diode. This strips the phase information from the signal leaving the amplitude (envelope of the original signal) bobbing up and down at the symbol rate. Turns out that the phase of this envelope signal is related to the timing offset of the PSK signal. The phase can be extracted using a single point Discrete Fourier Transform (DFT).

Here’s an example using some high school trig functions. Consider a simple BPSK signal that consists of alternating symbols ….,-1,+1,-1,+1….. Once filtered, this will look something like a sine wave at half the symbol rate, r(t)=cos(Rs(t-T)/2), where T is the timing offset, and Rs is the symbol rate. So if Rs=50 symbols/s (50 baud), r(t) would be a sine wave at 25 Hz, with some time offset T.

If we square r(t) we get s(t)=r(t)*r(t) = 0.5 + 0.5*cos(Rs(t-T)), using the trig identify cosacosb=(cos(a-b)+cos(a+b))/2. The second term of s(t) is a sine wave of frequency Rs, with phase = RsT. So if we perform a single point DFT at frequency Rs on s(t), the phase will be related to the timing offset.

That’s pretty much what happens in rx_est_timing(). We use the parallel QPSK signals, and a nice long window of modem samples to get a good estimate in the presence of noise and frequency selective fading.

linux.conf.au News: Open Source for Humanitarian Tech Miniconf at Linux.conf.au 2015

Wed, 2014-09-17 22:27

Linux.conf.au is pleased to announce that the Open Source for Humanitarian Tech Miniconf will be part of Linux.conf.au for the first time in Auckland, New Zealand during January 2015.

Technology is increasingly important in humanitarian response. Now responders are better connected to digital volunteers, more advanced tools such as unmanned-aerial vehicles give a better review of post disaster situations and great quantities of data can be collected and analyzed. Often these solutions are not expendable and are based on expensive proprietary solutions.

The Humanitarian Tech Miniconf will focus on two main audiences:

  1. Existing technologists who are interested in ways they can assist with technology in humanitarian response.
  2. Allowing existing projects and participants to share what they are working on and look for ways to integrate.

Technologists who work on UAVs, mesh networks, data collection platforms and content management will be invited to speak, and humanitarians to give a background in humanitarian response to those not familiar.

Kate Chapman is the Executive Director at the Humanitarian OpenStreetMap Team. Her most recent work has been in Indonesia working on a pilot program over the past year analyzing the feasibility utilizing OpenStreetMap for collection of exposure data. This project has hosted a OpenStreetMap mapping competition, a month long event to map critical infrastructure in Jakarta and assisting community facilitators in moving from hand-drawn maps to digital maps. Previous to working at HOT Kate was involved in development of multiple web-GIS applications including GeoCommons and iMapData.





Andrew Pollock: [life] Day 231: Kindergarten, cleaning, administrivia, swim class and dinner out

Wed, 2014-09-17 21:25

Today was a glorious day, and the universe was very kind to me.

I couldn't quite get myself motivated to go for a run before my chiropractic adjustment, so I had a nice relaxed start to the day instead.

I decided to get the cleaners back for a regular clean, and it was such a much better use of my time. I used the time I recouped to clean out my email inbox, and sort out a whole bunch of things that had been piling up on my to do list.

I biked over for my massage, and my massage therapist said he'd book a Thermomix demo with me, that was pretty awesome of him. Biking home, I decided to phone in an order for a burger from Grill'D and just continue biking over to pick it up. On the way down Oxford Street, I found a $20 bill on the road, so that paid for lunch for me. I was pretty stoked.

On the way home, I ran into my yoga teacher. I love my little village.

I had a little bit of time before I had to head to Kindergarten early to chair the monthly PAG meeting. Because the weather was so nice, I decided to bike in for it. It's hard to believe that Term 3 has ended now. The year is flying by.

We biked home, and only had about 20 minutes before we had to turn around and bike to swim class. After swim class, on a whim, I decided we should go out for dinner, so we biked down to Oxford Street and had some gyoza for dinner and biked home.

Tomorrow's going to be an early start and a big day, and apparently Zoe woke up early this morning, so I got her to bed a little early tonight. It's pretty hot tonight, so hopefully she'll sleep okay.

Andrew Pollock: [life] Day 230: Kindergarten, training, tennis

Wed, 2014-09-17 21:25

Yesterday was a busy day, and it left me quite drained by the end of the day.

I had my first day of Thermomix Consultant training. It went fine. I learned that the TM31 has a retractable cord. Who knew?! All this time I've been wrapping it all over the place when I take it out of the house.

I had to leave a bit early to pick up Zoe from Kindergarten and take her to her final tennis lesson of the term. It was a pretty hot day, but it went well.

After that, we dropped into the local coffee shop for a milkshake and cookie with Megan and her Mum, before we headed home.

We didn't have a huge amount of time at home before we had to leave again to meet Sarah at the train station to drop Zoe off. I then jumped on a train to meet Anshu in the city for dinner, which was a nice way to unwind.

linux.conf.au News: The Kernel Miniconf will be at Linux.conf.au 2015

Wed, 2014-09-17 13:27

The linux.conf.au 2015 conference is pleased to announce the Kernel Miniconf will be part of the programme in Auckland, New Zealand.

The linux kernel is the world's largest open source project and is at the heart of every linux distribution. The miniconf will be about all things kernel and is targeted mainly at experienced developers. Any interested parties will be welcome as always.

Key areas of discussion will be:

  • New developments and APIs
  • Pain points for users
  • Process/Community issues
  • Testing!!!

Tony Breeds is organising this year’s Kernel miniconf. He is a kernel developer focusing on powerpc. In his spare time Tony also maintains the kernel cross compilers on kernel.org





Chris Yeoh: Nova V2.1 API Plans in Kilo

Wed, 2014-09-17 13:26
Completing port of code to V2.1 API

With Juno now closed to new features we’ve started looking at what we plan to do in the Kilo development cycle. As mentioned in a previous post most of the V2 API had been implemented in V2.1 with the exception of the networking APIs. The first and highest priority will be to complete and verify the V2.1 API is equivalent to the V2 API:

  • Finish porting the missing parts of the V2 API to V2.1. This is primarily networking support and a handful of patches which did not merge in the Juno cycle before feature freeze.
  • Continue tempest testing of the V2.1 API using the V2 API tempest tests. Testing so far has already found some bugs and there will be some work to ensure we have adequate coverage of the V2 API.
  • Encourage operators to start testing the V2.1 API so we have further verification that V2.1 is equivalent to the V2 API . It should also give us a better feeling for how much impact strong input validation will have on current users of the V2 API.
Microversions

Support for making both backwards compatible and non-backwards compatible changes using microversions is probably the second most important Nova API feature to be developed in Kilo. Microversions work by allowing a client to request a specific version of the Nova API. Each time a change is made to the Nova API that is visible to a client, the version of the API is incremented. This allows the client to detect when new API features are available, and control when they want to adapt their programs to backwards incompatible changes. By default when a client makes a request of the V2.1 it will behave as the V2 API. However if it supplies a header like:

X-OS-Compute_Version: 2.214

then the V2.1 API code will behave as the 2.214 version of the API. There will also be the ability to query the server what versions are supported. Although there was broad support for using a microversions technique the community was unable to come to a consensus on the detail of how microversions would be implemented. A high priority early in the Kilo cycle will be to get agreement on the implementation details of microversions. In addition to development work required in the Nova API to support microversions we will also need to add microversion functionality to novaclient.

API Policy Cleanup

The policy authorisation checks are currently spread between the API, compute and db layers. The deeper into the Nova internals the policy checks are made, the more work there is needed to unwind in case of authentication failure. Since the Icehouse development cycle we have been progressively been moving the policy checks from the lower layers of Nova up into the Nova API. The draft nova specification for this work is here.

The second part of the policy changes is to have a policy for each method. Currently the API gives fairly inconsistent control to operators over how resources can be accessed. Sometimes they are able to set permissions based on a per plugin basis, and at other times on an individual method granularity. Rather than add flexibility to authentication to plugins on an ad hoc basis we will be adding them to all methods on all plugins. The draft nova specification for this work is here.

Reducing technical debt in the V2/V2.1 API Code

Like many other areas of Nova, the API code has over time accumulated a reasonable amount of technical debt. The major areas we will look at addressing in Kilo are:

  • Maximise sharing of unittest code
  • General unittest code cleanup. Poorly structured unittests make it more difficult to add new tests as well as make it harder to debug test failures.
  • API samples test infrastructure improvements. The api sample tests are currently very slow to execute and there is significant overhead when updating them due to API changes. There are also gaps in test coverage, both in terms of APIs covered and full verification of the responses for those that do have existing tests.
  • Documentation generation for the Nova API is currently a very manual and error prone process. We need to automate as much of this process as possible and can use the new jsonschema input validation to help do this.
Feedback

The planning for the work that will be done in Kilo is still ongoing and the API team welcomes any feedback from users, operators and other developers. The etherpad where work items for Kilo can be proposed is here. Note that the focus of this etherpad is on infrastructure improvements to the API code, not new API features.

The Nova API team also holds meetings every Friday at 00:00UTC in the #openstack-meeting channel on freenode. Anyone interested in the future development direction of the Nova API is welcome to join.

Simon Lyall: Another run in with the Electoral Commission

Wed, 2014-09-17 11:27

After already having trouble Electoral Commission banning photography in polling places I now get a threatening email from them.

Yesterday I made this Tweet:

 

Exit poll of people voting in NZ election at London High Commission Greens 35% Nat 32% Lab 26% http://t.co/03ANv9zDL2 #nzpol #decision14

— Simon Lyall (@slyall) September 16, 2014

and today I get the following email

Subject: Electoral Commission complaint – London exit poll posted on Twitter account

Dear Simon,

The Electoral Commission has received a complaint with regard to an exit poll being taken and then published on the Twitter account of @slyall. We understand that this is your Twitter account.

Under section 197(1)(d) of the Electoral Act 1993, it is an offence to conduct a public opinion poll of persons who have voted (exit polls). Section 197(1)(d) states:

197 Interfering with or influencing voters

(1) Every person commits an offence and shall be liable on conviction to a fine not exceeding $20,000 who at an election—

(d) at any time before the close of the poll, conducts in relation to the election a public opinion poll of persons voting before polling day

In order to assist the Commission in considering this complaint, could you please provide the following information:

1.         Who conducted the exit poll and when was it conducted?

2.         How did you receive this information?

3.         Any other information you believe to be of relevance to the Commission’s consideration.

4.         How you might remedy this matter.

Can you please provide the above information by 5pm, Friday 19 September 2014. In the first instance, to avoid further complaints, you may wish to remove the Twitter post.

Please telephone me if you wish to discuss this further.

I’ll update as things develop

BlueHackers: Quitting cigarettes

Wed, 2014-09-17 04:03

Why is it having mental illness and smoking go hand in hand. I’m looking closer to getting a foot in the door with my dream job doing something I love. I also plan to quit smoking again with my fiance and two friends. It’s not going to be easy but I went seven months not smoking. I really don’t enjoy it and it costs too much. That and every cigarette takes eight minutes off my life. I’ll keep you readers of bluehackers posted about the job. I’m excited..

Brendan Scott: brendanscott

Tue, 2014-09-16 23:29

Apparently Microsoft has bought Mojang, the game studio that brought us Minecraft.  I find it hard to think of a worse cultural match than this one – Microsoft has spent the last twenty years, for example, trying to move its customers off a once off license payment and into a subscription model.  It reminds me of the last Microsoft game I ever played (Mechwarrior Vengeance – no, seriously).  Microsoft bought out the Mechwarrior franchise and (IMO) killed the magic.  My guess is that Minecraft’s days (or at least Minecraft’s days of magic) are numbered.



David Rowe: SM1000 Part 5 – Mysterious Triangle Waves

Tue, 2014-09-16 22:30

Getting close to Beta now.

I have just spent a week tracking down a mysterious 256 Hz low level (30mVpp) tone that ended up being a software configuration error in the DAC initialisation code! However before that I thought it was a noise issue caused by PCB layout, or the wrong sort of bypass capacitor. I also popped another uC looking for it, costing a few days while I had the dud uC removed (thanks Matt) and I loaded a fresh one. Think I better stick to software…..

To get to the bottom of the problem I partially loaded a “minimal” 3rd SM1000. Just enough parts to make the uC run the dac_ut unit test program, power supply bypass, STLINK, crystal oscillator, boot mode resistors. Only about 1 hrs soldering, quite remarkable really.

Here is the mysterious triangle wave:

Michael Wild DL2F2 in Germany has built his own SM1000, using a PCB I sent him and the parts off our Digikey BOM. That’s a pretty exciting confirmation of the design. Having a another unit running has been very useful when making comparative tests. Here is Michael’s SM1000:

Michael, Rick KA8BMA, and Matt VK5ZM have also been very helpful in suggestions when I have been debugging. Thanks guys! Matt has also been explaining to us how ceramic caps can lose up to 80% of their C as their working voltage is approached. So best to use tantalum or electrolytic capacitors for noise sensitive applications like power supply and analog rail filtering (e.g. C25, C28, C29, C10, C12 on the SM1000). I could hear the noise drop when I soldered an electrolytic capacitor across C25 (input to the SM1000 switching power supply).

Right now I’m trying to reduce some remaining noise sources and soon hope to test over the air to see how the SM1000 works with large RF fields nearby, and also ensure it works OK with a couple of HF radio models. Rick is busy updating the schematic and PCB with a bunch of small changes we have picked up working on the prototypes.

We have a quote for the Qty 100 beta run, and are still on target to ship SM1000s in 2014. As soon as we have completed testing the prototypes we will kick off the Beta run and I’ll start taking pre-orders. Lots of work required on the software, but I figure that can wait until the Beta hardware is getting made. I want to take the open source approach of release early and release often, and that means getting betas into your hands ASAP.

linux.conf.au News: Clouds, Containers and Orchestration Miniconf at LCA 2015

Tue, 2014-09-16 12:27

"Software defined everything," DevOps, and cloud are driving open source further and faster than we might have imagined possible just a decade ago. Most recently, Docker containers and orchestration have opened up all kinds of new opportunities to develop, deploy, and manage software from the developer's desktop well into production.

The linux.conf.au 2015 organisers are pleased to announce the Clouds, Containers, and Orchestration miniconf at LCA in Auckland, New Zealand during January 2015. The miniconf will focus on the open source tools and best practices for working with cloud tools, containers, and orchestration software (e.g., Kubernetes, Apache Mesos, geard, and others). We'll have the leading developers working on those tools, as well as users who are deploying them in real production environments to share their knowledge and show where tools will be going in 2015.

Joe Brockmeier, the miniconf organiser, has a long history of involvement with Linux and open source. Currently he works on Red Hat's Open Source and Standards (OSAS) team, and is involved with Project Atomic, the Fedora Project's Cloud Working Group, is a member of the Apache Software Foundation. He is a technology journalist and has written for ReadWriteWeb, LWN, Linux.com, Linux Magazine, Linux Pro Magazine, ZDNet, and many others.





Andrew Pollock: [life] Day 229: Kindergarten, meetings, climbing course preparation and a car wash

Mon, 2014-09-15 20:25

Zoe slept well last night, and after helping make breakfast, which has become her new favourite thing, we biked to Kindergarten. The Kindergarten class photos had come back. Zoe took another very beautiful portrait photo this year.

I dropped by Jason's place to have a cup of tea and blow off some steam from a negative parent interaction I'd had the previous week, and then headed home to do some more preparation for next weekend's top rope climbing course.

I had a midday meeting with one of the Directors of Good Price Discount Pharmacy to bounce some ideas off him. I'm pretty much ready to abandon my home delivered prescription idea, as I don't think it's going to be viable. I'll have to do a post mortem write up of that little adventure later.

I did a bit more preparation for my climbing course after the meeting, and then biked to Kindergarten to pick up Zoe.

We biked home, and then grabbed the car and took it to the car wash to get it cleaned after Sunday's beach outing, and after a stop off at the health food shop to get some more kids' vitamins, we returned home again.

Zoe only got to watch a little bit of TV before Sarah arrived to pick her up.

I used the rest of the evening to get some housework done before going to yoga class.

Stewart Smith: Is Python the new BASIC

Mon, 2014-09-15 12:26

Today I managed to finally find a way to express what I’ve been thinking for a while: “Python is the new BASIC”. Think about it: it’s easy to get started in, there’s books and tutorials on it everywhere, a bunch of real world software is actually written in it and with all the different versions and modules (and versions of modules) there’s a billion subtle differences to trip you up.

There’s also the group of people (like me) who don’t particularly like it, for a bunch of quite valid reasons. The lack of being strongly typed is a huge barrier for me.

I am of the opinion that the ideal language with the ideal compiler would not let buggy code compile. It may not be as easy to program in this hypothetical language, but seeing as code has to exist and be debugged for order of magnitudes more time than it takes to write it, making it harder to write bugs is a good thing. After all, my experience with Python apps is that bugs manifest themselves at run time, to the user, rather than to the developer at the time of writing. Also, compiler error is better than unit test failure.

Discuss.

BlueHackers: More exercise and happiness

Mon, 2014-09-15 06:55

So I managed to last one hour the.other say doing boxing related exercises. After I had cooled down I felt great. Those endorphins are so good for me. I want more but I’m not good at wanting to exercise..

Sridhar Dhanapalan: Twitter posts: 2014-09-08 to 2014-09-14

Mon, 2014-09-15 01:27

Linux Users of Victoria (LUV) Announce: Adjourned 2014 LUV Annual General Meeting

Sun, 2014-09-14 15:28
Start: Sep 20 2014 15:30 End: Sep 20 2014 16:15 Start: Sep 20 2014 15:30 End: Sep 20 2014 16:15 Location: 

Boardroom, Electron Workshop, 31 Arden Street, North Melbourne

Link:  http://www.electronworkshop.com.au/

Confirmation of adjourned LUV 2014 AGM

This notice is to confirm that Linux Users of Victoria Inc. will be holding the adjournment of its Annual General Meeting, on Saturday 20th September 2014. The meeting will be held in the Boardroom of Electron Workshop at 3.30pm.

Electron Workshop is on the south side of Arden Street, about half way between Errol Street and Leveson Street. Public transport: 57 tram, nearest stop at corner of Errol and Queensberry Streets; 55 and 59 trams run a few blocks away along Flemington Road; 402 bus runs along Arden Street, but nearest stop is on Errol Street. On a Saturday afternoon, some car parking should be available on nearby streets.

LUV would like to thank Electron Workshop for making their boardroom available for this meeting, also Red Hat for their help in obtaining the Buzzard Lecture Theatre venue and VPAC for hosting, and BENK Open Systems for their financial support of the Beginners Workshops.

Linux Users of Victoria Inc., is an incorporated association, registration number A0040056C.

September 20, 2014 - 15:30

read more

linux.conf.au News: Linux.conf.au 2015 announces the Multimedia and Music Miniconf

Sun, 2014-09-14 13:27

Linux.conf.au 2015 are pleased to announce that the Multimedia and Music Miniconf will be part of the programme in Auckland, New Zealand.

The Miniconf’s website is at http://www.annodex.org/events/lca2015_mmm/ where the Call for Papers and other information will be published soon.

Multimedia and music are a significant part of how information is produced and consumed in our increasingly connected world. The Free and Open Source Software (FOSS) ecosystem provides a rich collection of software tools allowing the consumption and creation of multimedia. The Multimedia and Music Miniconf at LCA 2015 will bring users and developers together to present, discuss and experience what FOSS multimedia and music software has to offer for content consumers and producers alike. The miniconf will close with an informal demo/jam session to allow FOSS community members to showcase their creations and inspire others.

This miniconf will appeal to a broad range of community members who have an interest in multimedia and music on open source platforms - users and developers alike.

The Multimedia and Music Miniconf is being organised by Jonathan Woithe and Silvia Pfeiffer who have also convened previous Multimedia + Music miniconfs at lca in 2011 - 2014. Previous years' proceedings can be found at http://www.annodex.org/events/lca2014_mmm/

Jonathan, a Linux developer from Adelaide, Australia, has been a user since early 1990s, both privately and at work. Jonathan's primary open source focus is presently on software related audio and video production. He is one of the primary developers of the FFADO project (Free Firewire Audio Drivers ) and maintainer of the Fujitsu laptop driver in the Linux kernel.

Silvia has a long history of working on open media technologies through Annodex, Xiph, and more recently Mozilla and Google with the HTML5 video element and accessibility. At Google, she also became a WebKit/blink contributor. She is co-editor of the WebVTT and HTML5 specs at the W3C and now works for NICTA in Sydney. As well as the LCA Multimedia and Music Miniconf she has helped organise the LCA Digital Arts miniconf in 2006, and was an organiser of the Foundations of Open Media Software (FOMS) developer workshop in 2007, 2008, 2009, the two in 2010, the FOMS track at OVC 2011, and the ones in 2012, 2013. Silvia wrote the "Definitive Guide to HTML5 Video" in 2010.





Andrew Pollock: [life] Day 226: Play date, Science Friday, more baking, a trip to the airport and a dinner play date

Sat, 2014-09-13 22:25

I'm so over baking. The pumpkin scones were a total fail. The dough was so sticky I couldn't work it, so it got consigned to the rubbish bin.

Matthew came around for another play date, this time with his mother, Mel and little sister, Olivia. I baked a couple of loaves of gluten free bread while chatting with Mel and the kids all had a good time, and then we had some lunch.

For Science Friday, I thought I'd get some dry ice and put it in water. I'd found a dry ice place over in Woolloongabba, and so I popped over there and grabbed a 5 kg block before Sarah dropped Zoe off in the morning. Matthew thought it was pretty cool too (no pun intended). Unfortunately, Zoe tried picking it up before I had a chance to tell her not to, and got a bit burned on her fingertips, but after 10 minutes under running water, she was okay. The block in the water did some interesting things. The water around the block froze, and so the reaction of the dry ice and water slowed down, but occasionally the ice would crack with a big pop and more vapour would escape. It was fun to have just bubbling away off to the side while the kids played.

After lunch, we all played with the kinetic sand for a bit before they went home, and then I headed over to Mum and Dad's to pick up some more baking that my Mum had made. As I hoped, Zoe fell asleep in the car on the way there, and I managed to do the pick up and return to drop all the baked goods off while Zoe napped.

Anshu's flight was delayed, which worked out well, meaning I could drop off the baked goods before picking her up from the airport, even if it did mean more criss-crossing around town. We still ended up with about an hour to kill at the airport, which was fine. We wandered up and down the terminals, and got to watch all the airport operations. A random old man gave me a CD of nursery rhymes, which I'll be examining before Zoe listens to them.

While we were at the airport, Eva and Layla's Mum invited us over for dinner, which suited me fine, since the house looked like a bomb had hit a Kindergarten/bakery combination, so we headed straight to their place for dinner after Anshu's flight got in.

We had a great dinner there, and the girls had lots of fun playing with each other. It ended up being quite the late night, so I was grateful that Zoe had had a bit of an afternoon nap.

linux.conf.au News: Debian Miniconf returns to Linux.conf.au in 2015

Sat, 2014-09-13 13:27

We are excited to announce the return of the Debian Miniconf to Linux.conf.au after a break of 6 years. The Miniconf will run by Andrew Ruthven for a full day of Linux.conf.au 2015.

Debian was the earliest Linux distributions to be open for every developer and user to contribute their work. It continues to be the most significant distributor of Linux that is not a commercial entity (and even then, a number of commercial entities base their distributions on Debian).

As Debian remains a key part of the Linux ecosystem, this miniconf will collect together people from across the distros as there are a number of common interests.

Andrew is a Developer from Wellington, New Zealand, he has been running Debian on his home boxes since Bo was released and installed it using a shoebox full of 3.5" floppies. His first Bo install has been continually upgraded ever since, motherboards may have changed, RAID disks replaced, but it is still the same computer: cerberus.

In addition to using Debian at home, Andrew has been able to run Debian at every workplace he's had, both on workstations, laptops and servers. In 2012 Andrew became a Debian Maintainer and intends on upgrading to a Debian Developer when he has time.

He was the co-director of Linux.conf.au 2010

Tridge on UAVs: APM:Plane 3.1.1 released

Fri, 2014-09-12 13:18

The ardupilot development team is proud to announce the release of version 3.1.1 of APM:Plane. This is primarily a bugfix release with a small number of new features.



The main bug fixed in this release is a bug that could affect saving parameters and mission items in the FRAM/eeprom storage of PX4v1/Pixhawk/VRBrain. The bug has been in the code since January 2013 and did not cause problems very often (which is why it hasn't been noticed till now), but when it does happen it causes changes to parameters or mission items not to be saved on a reboot.



Other changes in this release:

  • support for using a Lidar for landing for terrain altitude (see the RNGFND_LANDING parameter)
  • improvements in the landing approach code, especially the glide slope calculation
  • added LAND_FLAP_PERCENT and TKOFF_FLAP_PCNT parameters, to control the amount of flaps to use on takeoff and landing
  • the default WP_RADIUS has been raised from 30 to 90. Note that the L1 controller may choose to turn after the WP_RADIUS is reached. The WP_RADIUS only controls the earliest point at which the turn can happen, so a larger WP_RADIUS usually leads to better flight paths, especially for faster aircraft.
  • send gyro and accel status separately to the GCS (thanks to Randy)
  • support setting the acceptance radius in mission waypoints (in parameter 2), which allows for better control of waypoints where actions such as servo release will happen
  • fixed GPS time offset in HIL
  • added RELAY_DEFAULT parameter, allowing control of relay state on boot
  • fixed sdcard logging on PX4v1
  • added GPS_SBAS_MODE and GPS_MIN_ELEV parameters for better control of the use of SBAS and the GPS elevation mask for advanced users

Happy flying!