When precision counts

The New York Times recently compared GPS watches to real-life distances. The watches came up short.

No watch was horrible, but none came within half a mile of reality. I know, I know – this is a first world problem. But bad GPS can be a real problem too.

Does accuracy matter?

I started Roadbud because bad accuracy in other devices got on my nerves. When Nike Plus chip lost track of my footfalls or the GPS teleported me a mile away and back, my run soured. I’d lose my groove and mentally fidget about the gadget. Once that started, I’d think about other annoyances. Is my shoelace loose? Am I wearing too much clothing? Will I chafe?

Poor accuracy yanks me from the flow and puts me in touch with my inner whiner.

Other runners need accuracy for different reasons. One runner I met at Quantified Self joked he’s logging history for his grandchildren. This has a grain of truth for many people – once you start recording your performance, it’s in the permanent record.

Other people just want accurate records for better understanding. Are you getting faster because you’re improving? Or is it just randomness from a flukey readout?

Why isn’t GPS perfect?

GPS listens for radio signals from precise clocks orbiting the earth on satellites, converting different times into distances and triangulating the distances.

The technology is amazing, but it isn’t foolproof. Radio waves get blocked by trees and tall buildings. Sometimes they get bounced around. The GPS math doesn’t provide an exact location – it gives an area instead (this is the blue circle in Google Maps).

On top of this, positions can be sampled far from each other. Each GPS location drinks precious battery juice, so most devices restrict how often updates are computed. This approach literally cuts corners – if you don’t know each corner, extra distances to the corners are ignored.

Why are some devices more accurate?

1. Better antenna Apple’s problems with the iPhone 4 antenna got more press than other manufacturers, but it’s common to the industry. Good signal = good GPS.
2. Extra sources GPS is terrific, but extra sources can help. Wifi or cell tower triangulation and accelerometers, can all improve accuracy.
3. Better chips The GPS chip is responsible for a lot of heavy math. It keeps track of 31 satellites (they each circle the globe, but use different orbits and have slightly different speeds), holds a very accurate clock, computes distance to the satellites, and then calculates position + accuracy. Most chips take mathematical shortcuts to use less battery, but some of the shortcuts are smarter than others.
4. Better post-processing How smart is the device in looking at the position from the chip? Ever snap your positions to a street grid? Computers can use many tricks to pinpoint your location even without a GPS reading.

Is GPS accuracy critical?

Official race distance measures

Accuracy is very important to me, but only one feature in the package. I can improve my accuracy by repeatedly measuring with a Jones counter. But who wants to work so hard for a statistic? I want to run wherever the mood takes me – not a premeasured course.

Too much effort works against my real goal of getting into my groove. Here’s what I need most:

1. Track where, how far, and how fast I run
2. Show me stats on a big display or through my earbuds
3. Don’t force me to use tiny buttons or confusing menus

I care about other stuff too – music, weather, graphing, etc. But most important, don’t mess with my flow.

Is the iPhone better?

Yes and no. I believe the chip and antenna are inferior to some GPS watches. The iPhone uses wifi signals and other improvements, but in a way that makes accuracy worse (to be covered in a future post). No personal experience, but Androids have an even worse reputation.

The iPhone shines in one area: app developers can adjust the location as needed (Roadbud uses fancy math to improve locations, but we need to do more).

Where do you come out?

Some runners were surprised by the NYT article. Some thought it carried a hysterical tone about a non-event.

The truth varies. GPS accuracy varies depending on where and when you run.  And some devices perform better under specific conditions.

What about your GPS – good enough for government work?

Related posts:

1. iPhone running app accuracy – is GPS enough?

Four wheels better than two?

I’m not always looking for speed accuracy.

I fondly remember dodging speeding tickets in my post-college Jeep CJ-7. The speedometer read low (honest, officer!) because of the oversized tires. But true mileage is far more important when I run.

Accuracy counts in a running app. Nobody likes missing out on their hard-fought mileage. Worse is grinning over a speedy workout and discovering you got played by a buggy app (this happened to me!).

Speed (and distance) can be measured through many different systems. I won’t trouble you with pitot tubes, but I’m about to get my geek on (I used to be a mechanical engineer). If the gory details bore you, skip to the bottom to find out what’s in version 1.05.

Rotations – how your car works

Rotations measure distance well when calibrated correctly (most people don’t rely on fat tires to flout the law). One app listens for clicks between your spokes and a straw stuck to your front fork (goofy, but it works even on the iPod touch). Too bad nothing rotates during runs or walks.

Accelerometer – how Nike plus works

An accelerometer (tiny chip that senses movement) feels the shock from your steps and multiplies by stride length. Unfortunately, stride length changes during a run. And those freakish cyclists have no stride length at all!

Nike uses a sophisticated formula that measures contact time. This improves accuracy, but is often wrong by 10% and doesn’t map your workout.

GPS satellite orbits

GPS – how Roadbud, Garmin, and Runkeeper work

GPS checks time on atomic clocks orbiting around the earth. It converts this time into distance and then calculates position in three dimensions. That’s the easy part – the Defense Department sweated the details years ago.

Applying GPS to running is a bit more difficult.

• Accuracy depends on listening to a number of satellites in good position. Since the satellites are always moving, sometimes they are too bunched up or just out of sight. The signal can also get blocked or bounced by buildings.
• High accuracy positions are mixed with wide guesses.
• The iPhone tries to “help” GPS by reporting location based on the wifi routers or cell phone towers it hears. A good idea in theory that doesn’t work well in real life. Skyhook Wireless provides this service to Apple and claims higher accuracy than reality – which leads to a lot of ugliness.
• GPS elevations can be wildly inaccurate because the satellites are closer to each other vertically.

Rainy day, precise position

Roadbud (and any other GPS device) has three big jobs:

1. Improve the raw GPS data
2. Determine which positions are legit
3. Combine with other data sources

Correcting GPS is tricky – if you include all the inaccurate positions, the trace jumps all over the map. If you go to the other extreme and drop all the fuzzy positions, you cut out corners and reduce mileage. The magic is in finding the right positions to include.

We’ve created a number of sophisticated methods to improve accuracy – and we’re still adding to the craft.

Here’s what we don’t do:

• Artificially smooth paths (shows a different, incorrect trace)
• Average current speed (takes forever to show correct speed)
• Ask users to turn off wifi (annoying and occasionally cuts out useful data)
• Blame cloud cover (or witches)

Roadbud isn’t perfect, but it works well, even when there aren’t many satellites around. If you ever meet up with an inaccurate run, email your screenshot to support@roadbud.com. We’ll do our best to track down the problem and keep it from happening again.

Related posts:

1. GPS Running Nirvana

Earbuds pipe more than music

I’ll confess. Running bored the hey out of me. The iPod turned my runs upside down – I suddenly rocked along to my own theme music. I ran longer. Even better, I ran regularly.

I’m not the only one. Brunel University compared students running with music vs. students running in silence. Music increased endurance 15 percent.

Still, the best runners I know avoid music. Not sure if they’re worried about safety or if tunes shout “amateur” in the elite world. Either way, I think they might be missing some of the less obvious reasons for tuning in.

1. Spoken stats: Big, clear numbers on your iPhone are terrific, but sometimes you’re pumping too hard to read the info. And squinting at numbers on a watch? Ugh.
2. Safety: Loud music doesn’t mix with situational awareness. But tying into your app means sending a map and calling a friend is only a few clicks away. Just keep the volume reasonable.
3. Podcasts: Serious runners often put so much time into running they need to scrounge for extra minutes. Podcasts allow you to combine runs with lectures, news, running articles – whatever you need to catch up on.

Big numbers if you're looking

When I’m running normal, I like occasionally hearing my pace, distance, distance, etc. Every half mile is the perfect wake-up in case I’ve let myself get distracted. Plus, I love the countdown after my halfway point. My reptilian mind wants to know how much longer before I stop – this just makes it easy.

If I’m training hard, I love hearing my stats over and over. This pushes me up and further. The stats button occupies the upper part of the iPhone, so it’s easy to tap without even looking. My personal need for easily-accessed stats drove Roadbud towards carefully-designed screens and application-level screen locking.

New version 1.04 is at the App Store: Roadbud 1.04 adds a number of improvements. The most important are better audio status, accuracy, and battery life. I’ll get deep into the hows and whys of GPS accuracy in a future blog post.

No related posts.

Clear numbers while you run

We might have luxuriated in the perfect spring weather outside. Instead, we’ve been plinking away on the keyboard. Our time sweating over a hot compiler paid off.   Roadbud is here to make your run rock!

What’s Roadbud anyway? It’s an iPhone app for runners that measures pace and distance. Roadbud’s built with useful functionality like integrated iPod controls, audio status (in a lovely Glaswegian accent!), screen-lock, and plenty more.

The great big safety button is my favorite feature. My stomach knots up when my wife runs alone. Now she can email me her exact location (and call) with a quick button press.

We’re discovering other uses too. I spoke with a runner last week about “Roadbud 911″. She told me this function was a must-have – her epilepsy is a constant worry. Personally, I’m hoping nobody needs to use the safety button. Extra peace of mind allows runners to move faster.

Features are important, but only if they fit together smoothly. Runners can’t fidget with gizmos during a workout. We’re polishing the app with commando usability tests. I’ll continue to man some local races to watch runners using Roadbud. If you see our table, stop by.

We’re uploading the next version today (longer battery life, spoken status improvements). We’ll keep improving (and you’ll get free updates installed to your iPhone). If you have any ideas or complaints, email support@roadbud.com.

Price: Roadbud Rookie has everything you need to track your run – and it’s free. Roadbud Pro adds audio alerts, safety button, and integrated iPod controls. The Pro version costs $9.99 - less than a single entry fee and hundreds less than some other GPS devices. To celebrate our launch, we’re charging only $0.99 (today only).

If you like Roadbud, spread the love. Get the word out on twitter, email, or just tell your running friends.

Related posts:

1. Roadbud version 1.0 launch slip
2. Testing Roadbud in a drenchquake

Time to learn Twitter

I created my first twitter contest three weeks ago. As a novice twitterer, I learned a hell of a lot along the way.

Here’s the contest: we need a tagline to describe Roadbud in just a few words. In return: one top-of-the-line iPhone.

The game is simple to describe, but difficult to win. I understand every facet of Roadbud and couldn’t possibly succeed. This challenge includes two thorny tasks: remove the fluff surrounding the Roadbud “core” and describe that core with a catchy phrase.

Our goals were clear: figure out the right tagline and interest strangers in Roadbud.

The third objective should have been “learn to twitter crowdsource”. Here’s what I discovered:

1. There’s no point in dragging out the competition. 90% of the entries (including the winner) came in the last few days. Run contests for two weeks max.
2. Even a good contest needs a network to go viral. Don’t run pricey contests without a good number of twitter followers.
3. Friends can help. I received many entries because popular twitterers like @32northSTABIL and @BobWalsh were kind enough to tell their friends. Rely on friends.
4. Good ideas come from anywhere. Some people started with bad taglines and sharpened them over time. Some foreigners (like @vikasguptajnu) worked hard and generated good ideas. Stay open-minded.
5. Describe exactly what you want. I goofed in deriding one of my taglines (“Run happy”). This misled contestants to spend time on long descriptions. Be specific.
6. Bone up on Twitter – there’s much subtlety crushed into 140 characters. I asked people to include the hashtag “#roadbud” because I expected attention for the company. Wrong. “#RBContest” would have explained better to bystanders. Immerse yourself in Twitter.
7. Preparation is everything. I badly wanted to deliver our new app along with the iPhone, but was wrong-footed by a delayed release. Plan for problems.

Some more data points:

• Some souls are gracious even when they’re competing hard. @thefitlounge took time to highlight good competitive entries – even after she created one of the best taglines. Looking for a motivational aerobic instructor in Maryland? Track her down.
• Professionals start with a leg up on everyone else. @joezuc is an amazing B2B internet marketer who generated 10 of the best 20 ideas. Fascinating to watch method in action. Joe twittered any idea that popped into his head and didn’t worry about duds. As time went by, his taglines homed in on the target tighter and tighter.
• Runners naturally grasp the benefits in running products. @Caratunkgirl, a triathlete,  forged three taglines only. When I checked my favorites with friends, they uncannily gravitated toward Mandy’s entries. She also has a funny, well-written running blog.

There were hundreds of terrific entries and I had a tough time narrowing down the field. In the end, there can be only one.

The winning tagline is “Fire up your run”. Congratulations, @Caratunkgirl. You are the proud new owner of one iPhone 3GS (and in a few weeks, Roadbud Pro).

Related posts:

1. Crowdsourcing our tagline

Almost ready to bloom

Roadbud was originally slated to ship by March 1. It isn’t ready – we’re still spraying for aphids.

I don’t like slipping the schedule, but we need to stand behind good software. Roadbud will ship around March 15 instead.

We’re excited about what this iPhone running app will do. A good number of other runners have been interested too – and signed up to be the first to get Roadbud. They relied on my projected March 1 release date – and I apologize to them. Anyone who already signed up to get launch notification will get Roadbud Pro for free.

Bear with us – it will be worth the wait.

No related posts.

Power in numbers

We had a great experience with crowdsourcing our logo a few days ago. Some people call this “the wisdom of crowds” – the idea that a crowd of people can come up with great concepts. It should be fun, even on the off-chance it doesn’t pan out.

Crowdsourcing relies on a mass of strangers to be smarter than you. I’ve always had wicked smart friends, so this should be easy for me.

We put up a prize for a Roadbud logo on 99designs.com. There were some mediocre designs, but crowdsourcing works. The crowd built a beautiful design in one day. Still messing with the technical side of showing it properly – check out the original design in the contest.

We’re hoping for a repeat with another contest – but this time we need a great tagline. We’re rewarding the best tagline with a new, top-of-the-line iPhone.

Here’s how you can help.

• Tell people about the contest. Facebook, email, twitter, whatever. Got a kid nephew who reads too much? Tell him.
  • I’ll be tweeting, “Need help creating tagline for great running app. Will pay one iPhone 3GS. http://roadbud.com/iphone-contest Please retweet.”
• Throw your hat in the ring
  • The contest is pretty simple and you’ll earn your karma points for the day

Related posts:

1. Seven lessons on Twitter crowdsourcing