23 February 2018

Polar M430 - Unusable Optical Heart Rate Monitor? Honest Review.

After many years my old Polar S625X started with geriatric problems. For example IrDA drivers bugs on Windows 10, buttons on watch, chest strap, Polar's announcement that PolarPersonalTrainer will be discontinued...
It was time to find a new HR monitor. My wife uses M400 and she is satisfied with it. M430 is its successor with optical heart rate measuring and some improvements. I read many reviews and M430 really looked promising. My wishes were: not expensive, GPS, Android and cloud support, optical HR measurement (I have enough problems with chest straps)...
M430 has everything I want and it wasn't expensive in January (189 EUR was my price in local store). The only reservation was an awareness that optical HR measurement isn't very accurate. Having that in mind, I have read this part very carefully on all reviews. The conclusion was that it isn't perfect, but is usable and that M430 has one of the best results in a field trial.

All features are well described on many websites (includes Polar's) and I won't repeat what other reviewers have already said. Only my disappointments follow.

1. Software
 The android software works nice and its main task is to synchronize data from M430 to the Polar Flow. With S625X I have used PolarPersonalTrainer. PolarPersonalTrainer will be closed down so all users must move to Polar Flow. Polar Flow looks modern, but PolarPersonalTrainer has more advanced functions and Polar could simply upgrade it with modern design and support for newer devices.
When I tried to transfer training data (10 years!) to Flow, I found out that this can't be done! WTF!
 I have asked Polar and get a classic corporative answer: "Thank you for contacting Polar customer care. Unfortunately you can only transfer data from PPT to Flow when using one of the following Polar products: RCX3, RCX5, RC3 GPS, CS500, CS500+, RS300X, RS800CX, CS600X, FT80, FT60, FT40 and FT7. I apologize for the inconvenience."
Crazily. I'm sure that all records (regardless of watch model) are stored in the same way in their database. They simply don't allow users of S625X to export their own records.

I have tried many tricks and I can at least export data from PolarPersonalTrainer (but only 25 records at once!!!) in XML. And don't expect that XML can be imported in Flow. It has to be a "political" decision, there simply isn't any technical reason.

Then I found the second clumsiness in Flow. You can't compare two (or more) training like you can in PolarPersonaTrainer. Isn't that one of the most interest thing you can do with your sports data?

2. Charging 
Polar M400 uses the standard (waterproof) micro USB cable that is available everywhere. With the M430 Polar has introduced a custom made port. If you have cable at home, you can't charge your watch in a car or in the office. Forget it. If you run out of battery, your M430 will be useless until you get your cable. Not only that, the connector on cable doesn't clip in very firmly.
As far as I know, Polar has problems with USB port corroding and charging on M400, so they had a reason to do that.

3. Battery
Many reviews glorify battery life on M430, but I'm not on their side. It is not bad and it shows good results if I compare it to competition, but for sure it can last longer. I expect to charge it every second (or third) day. If you have longer training, then expect to charge after every training.
Luckily, M430 has some settings where you can lower energy consumption.

4. Optical Heart Rate
Now we came to the main problem on M430. Its main function is HR measuring, but here it fails as deep as it can. What is wrong? First 10 or 15 minutes (or even half an hour) it shows wrong HR.
I now that watch should be positioned as described in user manual. I tried with tightening more, tightening less, move watch higher or lower on the wrist, cover watch and skin (cold factor), wearing watch hours before training... But it simply doesn't work ok at the beginning of training.
First minutes readings are far from real. It is winter in Slovenia, temperatures are near freezing point. It is understandable that on cold weather condition, the sensor performance (heart rate accuracy) could be effected as the blood flow is slower.
It is interesting that HR readings are real when I preparing for training. But after I start, numbers fall down to approximately 95-105 bpm. And stays in that zone for 10-15 minutes. It looks like my blood flow to hand almost stops when I start with training.

I asked Polar Support and here is their answer: "This is a common problem with OHR sensors. They need some time to adjust to your skin and you did everything right: moving the watch, covering it, etc. We recommend to put on the watch some time before your training. This allows your skin to get accustomed to the watch. When putting on the watch the blood flow will be hindered at first, but then the skin gets used to it and the blood flow will improve. But nonetheless it can happen, that the watch needs several minutes to calibrate itself to your pulse. This is not a bug, but an expected behaviour.
And as you described, it differs from person to person."

I accept that M430 reacts a little slower, this is usual behavior for optical sensors. I checked the datasheet of the manufacturer of sensor and they say that sensor's response time is 8 seconds. It is understandable and doesn't lose HRs because it simply writes them a little later.

I prepared a simple video to show the problem:

Note: Old S625X was with me some months ago when I was on medical heart test. And it was very accurate.
Cold is definitely an important factor here. I tried with ski gloves on my hands and although problem still exists, M430 readings were at least a little better.

Things are even worse. HR readings are inaccurate from time to time even when the device is in "good area". 

What can I say? M430 isn't usable if you want to follow your HR.
What will I do? I don't know yet. Maybe buying a chest strap is the cheapest solution. You can believe that I'm not very keen to buy an expensive strap because I already feel (at least partly) cheated from Polar. And then give them more money - hm, is this smart?
All in all, I am disappointed with M430, but otherwise (except upper issues), M430 can be a very interesting device. I'm also waiting for the higher temperature to see if readings will be more accurate.
I would also like to read your comments and suggestions.

28 November 2017

Ubuntu on VirtualBox – screen resolution problem

Over the years, we can read many questions about resolution problems from people who use Ubuntu as a virtual machine. How to solve this kind of problems?

Besides Windows, I am using Ubuntu server and there are (of course) no problems with screen resolution. However, from time to time, I install Ubuntu Desktop and I can confirm that I also was experiencing screen resolution problem. Because it was just a testing machine, I didn't care.
Some weeks ago, I installed Ubuntu 17.10 (Artful Aardvark) in Oracle VM VirtualBox. It works fine until some days ago when I got a small display with 800x600 resolution. I tried to change a resolution in Settings -> Devices -> Display, but I did not see the right part of the dialog to apply. Even after checking on other computers to see that there is no apply button and changing with keyboard, it did not work. As usual with such problems, I crawled the internet for the solution. There are many different solutions, but none of them works for me. Some of them were for different versions (or distributions) others simply did not work. 
However, all of them are looking for the solution inside Ubuntu, but none of them works.

After two beers, I got an idea to check all settings in VirtualBox again. I set the slider for memory available for video to maximum and enable 3D acceleration. It did not help, but I'm sure it is better to be on the green field.
UPDATE (29th November 2017): Latest version of VirtualBox (5.2.2) has problems with Ubuntu if 3D acceleration is enabled! It stops before login screen ... disable 3D acceleration helps.

Then I right click on small display icon in right bottom corner of virtual machine window. There is menu item named “Virtual screen 1” with listed different screen resolutions. I changed a resolution and … guess what … Ubuntu screen resolution changed! 

In my opinion, this the simplest solution if your Ubuntu screen resolution in VirtualBox suddenly changed. I would like to see other suggestions.

24 October 2017

Best phone battery saving tips

You can find battery tips on the web, but some of them are old and not up to date. I have collect conclusions from latest researches (for example Battery University, Google...) and for latest versions of Android. Follow this suggestions for keeping the battery in good condition.

Charging is the most important thing to keeping the battery in good condition without long-term damage.
1. Don't keep the phone plugged in when it's already fully charged. It keeps the battery in high stress which wears down the components/chemistry inside.
2. If you don't have to, try not to charge it to 100%
3. Charging your phone occasionally and not in big charging session. Maybe it looks that this isn't practical, but simply don't think about it. Whenever you can, plug in your phone for half an hour or so. There is no memory effect in Li-ion batteries!
4. Keep your battery cool. Heat is your batteries enemy. Remove the case if it insulates heat, don't put your phone on sun or heater...
5. Use original charger and cable. Especially if your phone uses quick charging. Most of the studies agree that quick charging can lead to the faster decline of the battery's lifespan. If you have time, use normal charging with the original cable. Don't use cheap chargers or cables. The amount of power your cable can carry is determined by the size of the wires inside - and cheaper cables use thinner wires, worse insulation, and shielding.
For example: OnePlus 5 (my review) uses fast DASH charging and it can charge up the battery from 0% to 60% in 35 minutes.

Android Settings
Battery life on your phone really depends on your usage. Especially screen brightness (usage on bright daylight!), bad signal, some battery hungry apps and some other stuff can drain your battery fast. But bellow listed Android settings can also be checked - maybe you don't use enabled features. Their location can differ from the version of your system (hint: use search when you are in settings).
1. Disable Auto Sync
2. Turn off Notification -> Apps were Auto Updated
3. Google Play Store -> Settings -> Do not Auto update app
4. Turn Off Google Now/Assistant
5. Settings -> Google -> Search -> Voice -> Disable OK Google Detection
6. Settings -> Google -> Search -> Disable Your Feed
7. Settings -> Wi-Fi -> Settings -> Switch Off -> Smart Wifi Switcher, Scanning Always & Network Notification
8. Settings -> Location -> Scanning -> Turn off WiFi & Bluetooth Scanning
9. Turn off Bluetooth, GPS, NFC
10. Disable Gestures
11. Disable Adaptive Brightness
12. Enable Developer Options (Settings -> About phone -> tap Build number 7 times ... and return back to find Developer Options).
13. Enable Doze Mode (in Developers Options)
14. Enable App Wi-Fi Multi/Broadcasting Filter
15. Set Window and Transition scale to 0.5 or None
16. Settings -> Backup & Reset -> Turn Off Backup My Data (you can turn this on occasionally)
17. Settings -> Advanced -> Recent App Management -> Normal Clear

What else?
You can check what is using your battery in Settings -> Battery. To get detailed information install a battery app with more advanced algorithms. My suggestion is BetterBatteryStats, but there are more of them. It will provide an insight to wakelocks, CPU states, Network stats... to help you find an app which uses the battery without your conscience.
There are many different ROMs and kernels for Android phones. Battery life is one the most discussed topics when you read about them. Can you can better battery life with changing kernel?
Yes and no. You can read The truth about kernels and battery life from an author of one of the most popular kernel (ElementalX).

But if your battery is old (even two years or more), if you charge battery "all the time" ... then in reality, you can't expect long battery life. It is time to buy a new one. My suggestion is to buy original. It is more expensive, but it will last longer, with better battery life and it will be safer (well, except Samsung :-)).