IpWatts

Record multiple power meter sources simultaniously

IpWatts is an application to log the data from multiple ANT+™ bicycle power sensors simultaneously to a single .csv file. Invaluable if you want to compare multiple power sensors in the real world. As well as the power data the app logs speed, cadence and heart rate if that data is available.

If you want a standard bike computer check out my cycling computer IpBike which uses the same underlying ANT decode app IpSensorMan but puts a sophisticated front end onto it. It dose a far better job at presenting and logging the data for most standard users with mapping, direct upload support as well as interval training capabilities and more.

https://market.android.com/details?id=com.iforpowell.android.ipbike

If you use this application and publish results I would ask you to acknowledge the use of the app and ideally link to it and IpBike in Google Play. Please feel free to email me with any issues. I consider this to be beta until it has had some more real world use, which given the specialist nature of the app may take some time.

IpWatts uses IpSensorMan to do the actual ANT interfacing you will be prompted to install it if you don't have it. You will need an ANT capable phone or a USB ANT stick and a USB Host capable phone.

You will first need to pair the sensors manually with IpSensorMan. Just go Start Ant then Search sensors. If there are multiple sensors active then go search sensors again to get another one open. You really want to try and start them up one at a time though if possible so you can be sure which is which. You can press on a sensor in the list and then name the sensor to make it distinguishable.

Having added the sensor just open IpWatts it will look for a single instance of the standard biking sensors + heart rate. Data from these is displayed at the top or left. It then opens as many other power sensors as it can, you get a list of the sensors with the current power value. You can calibrate a sensor by pressing it in the list. Once all the sensors you want are in the list just press start recording. When your done press stop recording. After pressing start you can leave the main IpWatts screen and recording will carry on in the background.

The logged file will be on the sd card in /Android/data/com.iforpowell.android.ipwatts/files/internal_logs/ the file name will be unique.

The data consists of a time stamp column followed by speed, cadence and Heart rate. Then for each power sensor 4 columns. First the watts value, then the accumulated Watt seconds value, then the pedal % or 127 if it is not available. Finally there is a 1 or 0 to indicate if data was received in this second, this should allow you to see if there are bad reception issues. If data is not received then it is latter filled in with the next good value which should be the average over the bad reception period provided the gap is not too big. For the accumulated Watt seconds the value will just stay the same during bad reception but then catch up on a good event. The pedal % can not be relied upon with bad reception, I just put in the last value. The speed is assuming a 2070mm wheel and is in m/s so you probobly want to do some spreadsheet work to convert it to your desired value.

Things look to be working with up to 4 power sensors with the simulator although it’s hard to simulate bad reception very well. With the current search methodology I use there is a maximum of 4 sensors of any type. You should be able to have IpBike active simultaneously with IpWatts.