Should app developers target Android first?

As a mobile app developer specialising in iOS I get a lot of comments from Android users to the effect that as there are now more android devices in the market than iOS devices, apps should be made for Android first or at least made for both at once.

There is no doubt that there are now more Android devices in the market. But does that mean that the extra effort (yes really) is worth it in terms of the usage an app would get?

How big is the "Android" target market?

Android is a fragmented market. Not only are there many screen and resolution sizes, there are many versions and not all are easy to develop for. In fact it only makes sense to develop for version 4.1 and later if you need to use modern features. This chart from Google illustrates that the actual interesting Android market is quite small. (These are from March 2013).

Not only are there many different screen sizes, each manufacturer supports different hardware features, and most importantly for media app makers, different streaming capabilities, so we need to choose the most popular devices to target. OpenSignal published a nice breakdown last year:

Happily, one is very dominant, the big green block is is the Samsung Galaxy SII followed by another Samsung and the HTC desire HD. So maybe we should go for the top three?

Note that we only target a few of the iOS devices out there. Xcode only builds for iOS 5.1 and later and there are really only three phone screens: 3.5", 3.5" retina and 4" retina plus two tablet sizes.

If I make an app for Android will they use it?

iOS users browse the web twice as much as Android users according to NetMarketShare:

This is hard to explain as Chrome and mobile Safari are pretty much the same.

If you are trying to make money, Android users are even less "engaged" than their iOS counterparts. Asymco published stats last year showing online shopping by OS.

So despite being dominant in numbers, Android shoppers are 21% compared to 77% for iOS. 

Even simple paid web browsing on flights as reported by GoGo shows a similar ratios:

App Annie shows that App store revenues for Apps in the Google Play store are rising but iOS is still four times that of the most "popular" devices.

Does it cost the same to develop for Android as iOS?

I am reliably informed by people who have commissioned Android versions of iOS apps that it costs 30% more to make an Android version than the iOS version. This could be because they are targeting too many Android devices or it could be that the Android SDK is not as mature as the iOS SDK and takes more effort to implement the same features.

I'm also told that there's more money in Android development, presumably a greater demand for those skills and a smaller supply of developers - so perhaps the developers are being paid more thus pushing up the cost.

Draft conclusion

I would love to see every app developed for every device, that includes iOS, Android, Windows Phone, Blackberry, Symbian, Ubuntu, Firefox and more, but resources are limited.

When evaluating Android for the first target compared to iOS I think about [proportion of v1.4+] * [proportion of Samsung GSII and HTC] * [usage of device] * [willingness to pay]. (Reminds me of the Drake equation).

The result is very small compared to iOS at the moment.

Why don't Android owners use their devices, and why do they complain so bitterly?

Android devices are generally cheaper than Apple devices. If you are not prepared to pay a few dollars more for the device, presumably you are not interested in paying for Apps. 

Feature phones, for people who just want to make calls and maybe send a text, have now disappeared and have been replaced by low end (old OS version) Android phones, so a proportion of the market have devices that have features they never really wanted.

My theory on complaints is that many consumers see an iPhone running apps and decide they want one. Those who don't go directly to an Apple store are met at a phone shop by sales staff who get a higher commission for selling Android phones so they tell the customer to buy this one as it's cheaper and "the same".

When these users start looking for apps beyond Facebook and Twitter they find that the pickings are slim. They're angry (with themselves) for falling for the sales talk and figure that abusing the developers for not porting to their cheaper phone is the most likely way to get what they want. (This post is my answer to that enquiry).

Cross platform development?

There are a lot of cross platform development toolkits. I think if it's possible to do something as a web app then it should be done that way so that it will be available on everything with a modern browser. But users like native apps for their responsiveness and robustness in an unreliable network environment. Facebook is a good example of this.

Cross platform development is always a compromise, it must abstract away the platform and often ends up being a lowest common denominator set of features. Users don't like apps that feel alien on their device.

I think the ideal approach, if funds were available, would be to have a team with a UX designer, graphic designer and specialist developers for each platform who can provide the "love" and focus to make an app that uses the features of each platform.

There is no silver bullet so far.

Apple needs competition

Don't misunderstand me, I want strong competition for Apple. It keeps them focussed and moving forward. I've spent much of my working life developing for platforms other than Windows and I know what it's like to miss out on Applications.

Apple has had amazing success in recent years making phones and tablets that non-computer nerds can learn to use in minutes. Apple is not targeting technical users in iOS and that group will be looking elsewhere for highly customisable devices. Fair enough.

I don't want Apple to "do a Microsoft" and start adding every feature they can think of - making the OS complex and confusing. 

The proposition that Android is the first choice for developers right now is not correct in my opinion.

I welcome your feedback.

Helping each other with StackOverflow and github

There was a story this week about programmers getting half their documentation from StackOverflow. It's certainly true for me, I'm there many times a day and often a search for whatever programming problem is confounding me ends up there. I do try to answer questions when I can on StackOverflow but it's very unbalanced so far.

The other site I get help from is github where people share code. I'm happy to report that at the prompting of a friend, I've contributed my first snippet of code to github.

It's a minimal iOS project that illustrates a way to make an iPhone app with a side menu - like Facebook and many other apps do these days. It does this by making a View Controller Container.

Let me know if you see any bugs or can improve it, or, as they say - "fork me on github".

Try the ABC Vegie Guide iPhone app - just out

I'm excited to announce that an app I've been working on in recent months is now in the Australian Apple App store.

Vegie Guide includes great wisdom from the popular ABC Gardening Australia team.

Getting an app to this point is a team effort, combining the skills of content authors, artists, user experience designers and a touch of engineering (my bit).

The app looks at your location and the time of year and recommends the best plants to plant. Once planted you can record progress in the form of notes and photos. As well as a plant encyclopaedia there are useful fact sheets to read.

I hope you'll try the app (it's free) and tell your friends about it. Please let us know what you think.

Wyong field day 2013 - quiet but entertaining

It was a pleasure as always to make the drive from Sydney to Wyong for the annual ham radio field day. As always, the NSW home brew group had a great display of home built equipment.

Modern equipment was on show.

I caught up with old friends, that's John and John, the one on the left is the station announcement voice on the ARNSW WIA Sunday broadcasts.

Software defined radio continues to be actively used and developed.

It was great to catch up with everyone.

Unfortunately, the dire weather predictions the day before frightened off the majority of car boot sales and attendees. My thanks to the organisers and the tea and cubes of cheese were fantastic as always.

Install Ask toolbar - are you kidding Oracle?

Every time my Windows computer upgrades Java - which is getting rather frequent and reducing my faith in that virtual machine as being safe - they try to push the Ask toolbar on me.

Now that we know that Twitter, Facebook and Apple have all been hacked through the vector of Java I think it's time to let this thing go. Having the updater attempt to install malware each time (and often tricking even me into it) just diminishes the Oracle brand. Stop it.

FreeDV codec2 presentation to Home Brew Group

Today at the ARNSW Home brew group, I presented a talk about FreeDV and codec2. Feeling unqualified to talk about how codec2 works, I wrote to David Rowe - the author of codec2 and last week we met up in Sydney where I interviewed David on video and that conversation is included in my talk.


Codec2 is an exciting new low bit rate voice codec that is open source. It is particularly suitable for digital voice over HF radio.

Thanks to Peter, VK2EMU for asking me to speak, John, VK2ASU for videoing the talk, and of course to David Rowe for taking the time to answer our questions on codec2.

Here's just the interview with David without my prattling on before and after:

Ham radio software on MacOS - try wine

MacOS users sometimes feel like second class citizens with so much great Ham Radio software for Windows and increasingly Linux. But I've found that many of the Windows versions of programs work brilliantly under the Wine windows api emulator. Here's WSPR for windows:

WSPR shows that audio in and out works well. One thing to note is that you run the installer and then must run the installed program which ends up at ~/.wine/drive_c/Program\ Files/WSPR/wspr.exe so I run it by:

• cd ~/.wine/drive_c/Program\ Files/WSPR/
• wine wspr.exe

Here's FreeDV receiving:

Here's me transmitting using the display microphone:

Audio actually works a little better than under real Windows where I'm unable to mix USB and on board audio. MacOS seems to have better built-in audio support. FreeDV is simply downloaded as a zip archive of a directory containing the exe and some shared libraries.

WSPRX unfortunately doesn't run by the way.

Building Wine

Windows are displayed using XWindows and for that you need to install XQuartz.

To install wine I recommend homebrew. I'm on MacOSX Mountain Lion and the build gets a link error and I needed to do this:

• brew update
• brew doctor # which reports that all is well, if not take advice
• brew rm libpng
• brew install libpng --universal
• brew install wine

So, great work by the wine and hombrew folks.

MacOS X users are not really short of Ham Radio Software

My opening remark gives the wrong impression, there's actually great Ham Radio software for MacOS these days. Machamradio has a great list.

ARNSW Sunday broadcast via digital voice

This morning VK2JI relayed the Sunday broadcast via digital voice using freeDV. Here's how I received the signal on 7190 from the Central Coast of NSW (I'm in Sydney).


Earlier in the broadcast:


Here's a screen shot.

There is discussion of all this on the digitalvoice google group.

Here is Ed's video of the transmit setup.

Upgraded to Bigpond Extreme, getting 80Mbps

We aren't on the three year plan for the NBN so I decided to go ahead and upgrade our cable internet to Bigpond Extreme.

Here is how it was before according to speedtest:

And here's how it is now:

So, oddly, ping time is slightly worse from 6ms to 9ms, but download speed is noticeably better going from 26Mbps to 80Mbsp. The experience of loading a web page is very nice indeed.

We no longer have a land line so we pay $110 per month and get 200GB of data. Incidentally, we've just installed a Skype phone - one that doesn't need a computer - and it seems to work very well.

Running a temporary syslog server

I'm trying to connect a SIP VOIP device VK2ASU kindly passed me to pennytel but it won't register with them. The device's web interface doesn't give much information but it does have the option to send logs to a syslog server on your network. I've figured out a very simple way to run up a server for temporary use using netcat.


$ sudo nc -ul 514
Password:
<13>[SIP]  | NOTICE | allocating transaction ressource 119 19277552-0131122292
<13>[SIP]  | NOTICE | allocating NICT context
<12>[SIP]  | WARNING| info: Name resolution requested.
<12>[SIP]  | WARNING| Doing asynchronous name resolution.
<14>[SIP]  | INFO   | MESSAGE REC. CALLID:19277552-0131122292
<12>[SIP]  | WARNING| OnEvent_New_Incoming4xxResponse!
<12>[SIP]  | WARNING| User need to authenticate to REGISTER!
<13>[SIP]  | NOTICE | allocating transaction ressource 120 19277552-0131122292
<13>[SIP]  | NOTICE | allocating NICT context
<12>[SIP]  | WARNING| info: Name resolution requested.
<12>[SIP]  | WARNING| Doing asynchronous name resolution.

This gets nc to listen to UDP on port 514 and it displays whatever comes in.

Homebrew hangout

I've just participated in a Google hangout with a buch of homebrewers around the globe using Google's amazing Hangout video conferencing. Thanks Jason Mildrum, NT7S, for organising it.

Participants were on Linux, Windows, MacOS and iOS. There is a bit of confusion caused by Google's display of the time of the hangout in the zone of the organiser so for me it kind of looked like I'd missed it.

It seems like there is a limit of ten video participants but we think you can have ten sending video but many more if they are just viewers. More experimentation is needed.

The only other issue was echo from people who had their sound on a local speaker, we think that is due to the latency inherent in a global conference call. I think headphones are a must.

It was great to meet everyone and talk about projects. We discussed Antennas, arduinos, Raspberry Pi, making PCBs with a CNC, Beach 40, and got a tour of a station.

Thanks to Jason for organising this, can't wait for the next one.

Preserving our digital photographs

Holiday season is family photo season and now that we’ve transitioned from film to digital photography the number of pictures we take is at an all time high. But while our family albums often have pictures taken a century ago, it’s likely that the current crop of snaps will be irretrievable in just a decade, unless we work to preserve them.

The oldest surviving photograph, taken in 1826 by French inventor Joseph Nicéphore Niépce, titled “View from the Window at Le Gras” is still visible today while the ink jet prints on my fridge from 2005 are badly faded.

Niépce covered a pewter plate in lavender oil containing dissolved bitumen and exposed it for eight hours to the sunlit scene outside. The exposed bitumen hardened and the rest was washed off to leave a permanent image.

Photography has got progressively easier since then, including Kodak launching the brownie in 1900 with the slogan “you push the button, and we do the rest”. Later mass market innovations included 35mm cartridges and instamatic cassettes (although I never liked them).

Film based photography peaked in 2000 at 85 billion photos (this estimate is based on the global use of silver in the process) but this year, now that we’re digital and don’t run out of film, it’s estimated to hit 380 billion pictures. (Whether this four-fold increase in snapping actually produces any better images is debatable).

The largest single archive of current images is Facebook who noted that they had 219 billion images as at September 2012.

From the time I was in my teens, until about two years ago, I selected the best images from each roll and glued them in a series of albums. Recently I find I’m showing images to family and friends via Instagram, Twitter and Facebook. My album series has ended and I fear that my digital image narrative my have ended too.

Often it is the images that capture the ordinary, the view of the kitchen bench, the junk near the TV, rather than the false smiling relatives that are the most rewarding in retrospect. But being able to keep everything is a double-edged sword.

My digital archival storage plan

While digital storage is reliable it is ironically brittle. I’ve used and thrown out: punch cards, data cassettes, eight inch floppies, 3.5 inch floppies, zip disks and CD ROMs will be next in line.

My Aperture library, containing all my serious (RAW) images for the past few years is under 90 Gigabytes. Many other images have been posted directly to Instagram and only survive in 612 square pixel format.

When much loved Panda the cat died recently after keeping us company for fourteen years, I realised how few images remain.

I have images all over the internet, on Google Picassa, Yahoo Flickr, DeviantART, MySpace, and MobileMe. The last ones, on MobileMe web albums were deleted when Apple closed it down earlier this year. Yes they gave me plenty of warning, but no, I never got around to looking at them or saving them.

Paying for online image storage provides some assurance that they’ll make an effort to contact you before disappearing. The act of renewing the payment details every few years also serves as a reminder. It’s not expensive, Google charges $5 per month for 100GB of storage, Yahoo charges $25 per year for “unlimited” storage - although I’m always a little suspect of unlimited things.

Hard disks get cheaper very fast and currently a terabyte drive is about $100 so a good plan is to purchase a new one each year and copy over the whole archive from last year’s disk plus all the new images. The act of re-copying, plus keeping a few past years disks provides some redundancy in case of mechanical failure.

Apple has photo stream and iCloud but at the time of writing I’ve seen enough weirdness to not trust their cloud services just yet. (Jobs should have purchased DropBox).

The answer for me is a combination of the annually refreshed external hard disks plus some online storage (in case the whole house goes up).

I’ve also started printing out a few pictures and the bound books from Apple and others are a nice update to the glued albums I used to keep.

More pictures are being taken than ever before but I don’t think they’re better. Sometimes I like to use a camera that slows me down and doesn’t track the faces automagically. My new years resolution is to take fewer, better pictures and make an effort not to lose them in a disk crash.

I discussed this topic with John Doyle on ABC RN Breakfast this week.

Correspondence with planning minister Brad Hazzard about ham radio antennas

I wrote the following letter to the NSW planning minister, Brad Hazzard on 18 November 2012:

The Hon. Brad Hazzard, MP

P O Box 405

Dee Why NSW 2099

Dear Mr Hazzard,

I am a member of your electorate and a licensed ham radio operator, VK2TPM.

I’ve recently heard that your new planning system for NSW does not include the streamlining of approvals for the antennas that we ham radio operators need to put up to pursue our hobby.

The antennas that most of us put up are no more unsightly than TV antennas and much less unsightly than many of the tall masts which are common in suburbs on the northern beaches. Further, I find the power poles and lines, along with the low hanging cable TV and internet wires, to be much more unsightly than the occasional ham radio antenna that my colleagues put up.

Ham radio is a wonderful hobby and serves an important public service in times of disaster when conventional communications is unavailable. 

Specifically, what I’d like to see is:

• Ground mounted radio masts or antennas of up to 10m height (or 5m above a roof if attached to a building) be exempt from a development application.
• Masts up to 15m should only require a simplifying permit based on given standards.

Victoria and South Australia have regulations like this. Can you explain to me why we can’t match this in NSW?

If I can be of any further assistance, or you’d like to visit my ham radio shack for a cup of tea, you’d be most welcome.

Sincerely,

Peter Marks

He replied:

17 Dec 2012

Dear Mr Marks

I refer to your letter concerning the construction of radio antennas without the need for

approval, as exempt development.

I would like to acknowledge the valuable work performed by amateur radio operators in

transmitting vital information during natural disasters and other emergencies when

traditional infrastructure fails.

Provisions of State Environmental Planning Policy (Exempt and Complying Development

Codes) 2008 (Codes SEPP) allow antennas and aerials to be erected on most lots in

NSW to a height of 1.8m above the highest point of the roof on a dwelling. This includes

aerials and antennas which may be erected at ground level such as those used by

amateur radio operators. In situations where there is a two storey dwelling, this allows for

the erection of an aerial or antenna that is around 10m high.

These standards are designed to balance the rights of owners to erect these structures

which are suitable to the scale of existing buildings, while minimising visual and other

impacts on adjoining neighbours.

I note your reference to the approval and location of traditional infrastructure and the

impacts they have on amenity. The erection and development of power poles and lines as

well as cable TV and Internet wires is governed by other legislation, including the

Telecommunications Act 1979, administered by the Commonwealth Government.

Amendments to the Codes SEPP have recently been exhibited for public comment.

Amateur radio operators raised concerns regarding the Codes SEPP and the ability to

erect radio masts and antennas. Each submission is currently being reviewed and I have

asked the Department of Planning and Infrastructure to pay particular attention to the

concerns yo rail- in finalising the SEPP amendment.

Should you have any further enquiries about this matter, I have arranged for Mr Michael

File, Acting Executive Director, Assessment Systems of the Department of Planning and

Infrastructure, to asist. Mr File can be contacted on telephone number 02 9228 6407.

Yours sincerely

HON BRAD HAZZARD MP

Minister

Codec2 and modem on a raspberry pi?

Encouraged by early success with FreeDV digital voice with codec2 it occurs to me that a great project would be to build the equivalent of these AOR digital voice modems. Looks like they sell for US$449 so to build something functionally equivalent based on a $38 Raspberry Pi is very attractive.

There's an interesting thread on the codec2 mailing list about running codec2 on a raspberry pi.

I imagine AOR are not too pleased about this prospect - if they are watching the road ahead, they would be working to build codec2 right in and they will pick up a potentially interesting early adopter market.

Looks like I'm not alone and ON1ARF is already working on this. Although he's using a pandaboard for decoding at this point.

We are at a fascinating time in Amateur Radio.

Update - audio on Raspberry Pi

Downloading and installing codec2 on the raspberry pi couldn't be simpler:

• sudo apt-get install subversion
• svn co https://freetel.svn.sourceforge.net/svnroot/freetel/codec2-dev codec2-dev
• cd codec2-dev
• ./configure
• make

To get the play utility, install sox:

• sudo apt-get sox

The test that encodes and then decodes out to the rpi's built-in audio works great:

• cd src
• ./c2enc 1400 ../raw/hts1a.raw - | ./c2dec 1400 - - | play -t raw -r 8000 -s -2 -

Next step, where I'm a bit stuck at the moment, is to record audio from an external USB headset. I plugged it in and you can list devices as follows:

• arecord --list-pcms

My USB Headset is a little Sennheiser one, so I get:

$ arecord --list-pcms

null

    Discard all samples (playback) or generate zero samples (capture)

sysdefault:CARD=headset

    Sennheiser USB headset, USB Audio

    Default Audio Device

front:CARD=headset,DEV=0

    Sennheiser USB headset, USB Audio

    Front speakers

surround40:CARD=headset,DEV=0

    Sennheiser USB headset, USB Audio

    4.0 Surround output to Front and Rear speakers

surround41:CARD=headset,DEV=0

    Sennheiser USB headset, USB Audio

    4.1 Surround output to Front, Rear and Subwoofer speakers

surround50:CARD=headset,DEV=0

    Sennheiser USB headset, USB Audio

    5.0 Surround output to Front, Center and Rear speakers

surround51:CARD=headset,DEV=0

    Sennheiser USB headset, USB Audio

    5.1 Surround output to Front, Center, Rear and Subwoofer speakers

surround71:CARD=headset,DEV=0

    Sennheiser USB headset, USB Audio

    7.1 Surround output to Front, Center, Side, Rear and Woofer speakers

iec958:CARD=headset,DEV=0

    Sennheiser USB headset, USB Audio

    IEC958 (S/PDIF) Digital Audio Output

Copy the device name from the list above and use it in arecord and aplay below. To record 10 seconds of audio from the USB headset:

• arecord -D sysdefault:CARD=headset -d 10 test.wav

To play that back to the USB headset:

• aplay -D sysdefault:CARD=headset test.wav

I can hear my voice but it sounds terrible. It would be an abuse of codec2 to use it as input. Any tips would be appreciated!

First HF Digital Voice contact with codec2 and FreeDV

I'm very excited to report that I've had two digital voice contacts on HF using FreeDV which runs codec2 by David Rowe. (There's also a very active digital voice Google Group).
Here's how Patrick VK2PN looks to me running 5W.

This mode uses about half what a sideband radio would use and is perfectly intelligible when it's working. The other bonus with a digital mode is the complete lack of background noise.

Here's how I look to Patrick on his panadapter:

Patrick has written up our contact from his side on his blog.

FreeDV is very easy to get going on Windows, I had a go at building it for Ubuntu Linux but ran into a few bumps in the road.

Here's a video from my end where you'll hear how Patrick sounds to me as we both reduce power.


After the contact with VK2PN I was also able to talk with Graeme, VK4CAG pretty well.

So, this is an extounding day! Great work by David Rowe and all those involved. It's fantastic to have a good quality low bit rate voice codec that is public domain. This is a great thing for Ham Radio and I would think will have reverberations through the voice over IP business as well.

Update - FreeDV under Wine

Stephen, VK2BLQ, has just pointed out that FreeDV seems to run well under Wine on Linux.

Update - FreeDV now builds on Ubuntu 12.10

The latest code from subversion now builds smoothly on Ubuntu 12.10 but for me the audio stutters for some reason so I'm still using the Windows version under Wine. I just heard VK4BD on 14.236 but couldn't decode more than the call sign.

Update - FreeDV on MacOS via wine

FreeDV appears to run ok on MacOS under wine but again I'm hearing audio stuttering. It looks pretty good though:

I installed wine with brew. Note that to get it installed you need to do the following:

• brew rm libpng
• brew install libpng --universal
• brew install wine

Then you cd to the directory with freed-windows and wine freed.exe

Current project - the "Beach 40" DSB transceiver

Peter, VK3YE, is an inspirational home brew designer and constructor. In a series of YouTube videos he demonstrates and then walks through the design of a simple double side band transmit, direct conversion receive, transceiver he calls the "Beach 40".

The minimalist QRP Transceiver group has drawn the circuit up (in the files section).

I started construction over the weekend but my oscillator didn't.

I'm using the "manhattan" or "paddy board" construction technique using bits of PCB cut with tin snips and superglued on to the base board as insulating islands. It's not as compact as "ugly" construction but the circuit is more obvious and it's very low profile. I'm thinking of stacking boards one above the other in the final box.

After some tips on non-starting oscillators from VK2ASU and VK2BLQ (who's also building one), I put a variable capacitor in place of the 390pF in the Colpitts oscillator and it started.

Peter's design has evolved through the YouTube video series, mostly in the receive audio switch to an LM386 but I am attracted to the all discrete transistor version if it can be made to work. It's much quieter in my shed than it is on Elsternwick beach.

Update

Stephen, VK2BLQ, is also building and it's looking good (click to embiggen):

His CRO is much fancier than mine but I'm a bit suspicious of that waveform from modulation of a 1kHz tone on 7144kHz:

VK2BLQ is powering ahead of me:

But I own Saturday....

Update. Does this look right?

I'm still on the balanced mixer. I'm feeding in a 2.2V peak to peak 1kHz tone and here's the modulated RF output I get.

Seems very low level and somewhat non-symetrical. The variable resistor changes it but the trimmer capacitor has very little effect.

Stephen is powering ahead and now can transmit, here's his latest work (I wish mine was as good).

Stephen writes "Hi Peter, seems to be real QRP final current less than 250mA can't read any power
on  the meter.

As can be seen on the CRO, the PEP is 20v p-p which is about 250mW or 1 watt if it were CW. I think the final transistor  is not right. It is  a CB radio final and should be good for 4W. Time to cook dinner and have a look later"

Update - My power strip

Like Stephen, I'm getting 20V p-p or 1W out which seems a little disappointing.

Don't worry I will find some heat sinks. Here's a top view:

Software Defined Radio talks

Today at the ARNSW Home Brew Group, we had two talks on Software Defined Radio, one dealing with VHF and up, the other on HF. First here's Gary, VK2KYP, who kindly gave me permission to post this video. Gary has previously purchased a FunCube dongle but finds a $20 DVB tuner works pretty well and is great value.



And here's Stephen, VK2BLQ, on HF SDR:

Feld Hellschreiber QRP beacon with arduino

I have been using a digital audio recorder to provide Hellschreiber test signals but this is clearly silly. So, thanks to Mark of the fabulous brainwagon blog I now generate test signals with an Arduino.

The Arduino sends port 13 (the one with the on-board LED) high and I use it to turn on a transistor to pull my final low. Off air locally it looks pretty good and the drift is quite mild.

I'm still running milliwatts with my big 2N2222a final transistor but Stephen, VK2BLQ can hear me 10km away fairly well over the noise. Here's how I look at his place:

On Sunday, November 25 2012, Stephen and I gave a little presentation about all this at the ARNSW Home Brew Group meeting at Dural NSW:

How to fix poor iPhone battery life

My iPhone 5 wasn't making it through the day. I was disappointed, but after a few simple changes it looks like it could even last two days.

My usage pattern is that I charge over night, get up at about 6am, listen to podcasts for an hour going to and an hour returning from work.

During the day I make a few calls, and use a lot of Wifi data. On the way home I use a bit of LTE cellular data to catch up with news feeds.

With the changes below, as you can see from the Usage screen to the right, after 11 hours without a charge my battery is still at 74%.

Long life suggestions

• Avoid polling for email. I was polling for GMail every 15 minutes, I switched to the GMail client (as I use Exchange for work email). So mail is pure push and it's instant.
• Turn off LTE unless you're in a good LTE reception area and actually plan to use it. LTE is very patchy here and I've noticed the phone running hot in my pocket trying to contact cell towers.
• Screen brightness under 50%.
• Choose a carrier with good strength at your home and office. Phones turn up transmit power is signal strength is low.
• Reset network settings: Settings>General>Reset Network Settings. I'm a little sceptical about this one but it forgets all those Wifi networks you've used once and stops the phone trying to join them again, unless you specifically want to.

Using Push instead of polling is the big one I think. Push is very efficient, it's a single TCP connection to Apple which all notifications come over (so I don't believe the number of apps that can push will make much difference).

Incidentally, all those tips you see about quitting applications that you aren't using are nonsense. iOS will only allow them to background for 10 minutes and then only for specific tasks like completing a download. The only exception is playing audio which you want anyhow.

Before the iPhone 5 I had a 4 (not the s). The battery was losing capacity after almost two years of daily cycles. The solution was to pay $9 for a replacement battery on eBay. It came with the tiny screwdriver and there are instructional videos on YouTube. It's easy and cheap to do.

I hope this clears up some mis-information I see around the place. Let me know how you go.

Update

Here's how my phone looks after 27 hours of not being plugged in and normal use for me. That includes quite a few hours of internet and podcast listening but no tethering. If you think you have a problem it would be useful to compare your usage with mine by the time you drop below 20% battery.

Feld Hellschreiber QRP beacon test

Stephen, VK2BLQ, and I continue to experiment with Feld Hellschreiber and I'm pleased to say that next Sunday, November 25th, we'll be presenting to the ARNSW Home Brew group meeting at Dural.

Today I did a test transmission with this little setup:

I've recorded "this is a test transmission from vk2tpm" on a digital recorder which is driving the simple audio keyer to key a two transistor QRP CW transmitter on 7027kHz.

Stephen is about 10km away as the crow flies:

He demodulated me like this:

Not great but amazing considering my transmitter. Come along next Sunday and we'll try to demonstrate across the room.

Red Blue 3D maps from Nokia

I'm a bit of a 3D fan. Nokia has a maps web app at here.net, somewhat like Google and Apple's and it has a unique feature of displaying in red/blue 3D. Here's a shot:

The view is somewhat similar to that which you get from Apple's map, clearly taken from a low flying plane. It's great to see some competition in the maps business.

Pixie 2 based Feld Hellschreiber transceiver

I've figured out that my keying of the CRK-10 CW transceiver is flawed and that I'm not shifting frequency so I've decided to start work on a dedicated Feld Hellschreiber transceiver based on the popular Pixie 2 design.

This clever little design uses the output transistor as a mixer during receive and my modification is to key it with rectified audio from the computer. It's putting out a very pleasing little signal (barely moves a power meter but thats fine for a mode like this) but my audio keying circuit needs work.

Digital QST now available via iPad app

I switched from a paper subscription to the ARRL's QST magazine some months back and have been distressed about the poor experience of having to read it through a terrible web based copy protection scheme.

Just noticed that there is now a QST app for iOS that makes it considerably more pleasant to read.

It's better but still pretty clunky. This feels like the output from some sort of cross platform publishing system. User interface buttons look alien. It surely should be in the Apple Newsstand and should use Apple's subscription system.

QST is laid out for print and it needs to embrace digital publishing by letting us read articles as tall scrollable streams rather than two or three columns of text.

It seems that it's published as images of the page, which makes it big and slow. While there are links, such as from the contents page, there is no text search. (In the end I'll want to search my whole collection for a phrase).

This is a good step in the right direction but it still needs work.

Tiny CW transceiver for Feld Hellschreiber

This morning I had a Feld Hellschreiber contact with Stephen, VK2BLQ on 40m. Here's how he looks to me:

And here's how I look to him:

Comparing the two waterfalls above I think I have too much RF gain which is leading to a noisy receive display.

My goal here is to be able to use a very simple, very small, CW transceiver with a digital mode. Next step is to get an audio driven keyer working.

Update

I've now got this working with the tiny CRK-10 CW transceiver via a simple audio keyer interface.

I'm using a little USB audio adapter and then you can see my simple audio transformer, full wave rectifier and 2N2222a transister to key the CRK-10. In the video below I test transmitting into a dummy load.


Stephen wrote "Good to work you on 40 Hell again.

The CRK10 has a very narrow filter, I was calling you back on 7030 several times, but not until I QSY to 7131.2KHZ that you heard me.

Your RST was about S3-5 but letters were good. Goes to show a microrig and pc  has possibilities.

The narrow filter kills the noise and makes the letters clearer.

I dug out  a couple of older T/R  boxes to mod for keying the tube TX directly. Don't think a relay is fast enough and is noisy. I'll use a powerfet rated for 100v and 1 amp as the Cathode current is 100mA and key up volts is quite high."

Here's how the QSO looked to me:

So aside from the fact that I'm off frequency, my reception is superior to my main rig.

Here is the simple keyer circuit. Small signal diodes, a 2N2222a and a few 0.1uF caps. The transformer is a little audio transformer, not sure what ratio.

I added a 3.5mm socket to the CRK-10 and connected it to the top of C22 where the transistor pulls low to key the carrier.

Thanks again to Stephen, VK2BLQ, for all his help at the other end but it looks to me that a truly minimal Feld Hell transceiver is quite practical.