CAT S31 Smartphone Review
For more than five years, the licensee "Catphone Mobile Ltd" has been producing rugged smartphones with the logo of the Caterpillar construction machinery company. The company's phones are certified to industry standard IP68 and military standard MIL-SPEC 810G. The manufacturer even claims that the standards of certification are exceeded in its own laboratories. However, as our test of the CAT S40 from 2015 showed, these devices are by no means indestructible.
However, CAT is not alone in the market of rugged outdoor phones and with a price of over 300 Euros (~$360), the S31 is not exactly among the cheaper competitors either. In addition to the Blackview BV8000 Pro, the CAT S31 has to compete with the Samsung Galaxy XCover 4, the S30 from Nomu and the AGM A8. The prices of competing devices range from a relatively inexpensive 180 Euros (~$216) (AGM A8) to 330 Euros (~$399) (CAT and Blackview).
Case
With a diagonal screen size of 4.7-inches, the CAT S31 is the smallest device in the reference group, but its robust case makes it very bulky. This is typical for such stable devices and should therefore not be considered negative. The smartphone is just as thick as larger devices in this class, not least because of the generously sized battery.
With IP68 certification and the military standard MIL-SPEC 810G, the S31 is suitable for almost all environments. It is dustproof, at 1.20 meters water depth up to 35 minutes waterproof and fall-proof from heights of up to 1.80 meters. With many ripples and edges, it is almost impossible for the smartphone to slip out of your hand. The manufacturer Catphone calls the appearance of the S31 an Easy-Grip-Design.
The device also feels very sturdy in the hand and has no flaws in its workmanship. Each port is equipped with a rubberized closure and the physical buttons are firmly seated in their respective positions.
Features
Like in the CAT S40 from two years ago, a Qualcomm Snapdragon 210 MSM8909 with the Adreno 304 graphics unit is used in the CAT S31. This entry-level SoC is sufficient to operate the Android 7.1 Nougat system smoothly. But for demanding applications, the chip was not suitable even in the year of its release. Therefore users should choose simpler apps. With 2 GB of memory and 16 GB flash memory, there is enough capacity for most applications. Only graphically demanding games should be avoided. A microSD card can be used to expand the internal memory up to 128 GB.
Memory and SIM-card slots are accessible from the outside and are protected by flaps. The SIM-card slot in particular is very tightly closed and can only be opened with a flat screwdriver. The buttons on the left and right sides of the device can also easily be felt when wearing gloves. The feedback for these buttons is very clear. In addition to the power button and volume control, the S31 is equipped with a freely assignable button. In the respective menu, different actions can be selected for both short and long presses of the button. For example, apps can be started, calls answered or notifications sent. Alternatively, the button can also receive a push-to-talk assignment.
Software
The CAT S31 is shipped with Android 7.1 Nougat and provides the user with a very tidy interface. In addition to a few preinstalled programs, Catphone provides the company's own app Toolbox. This is an app store in which the manufacturer has collected apps sorted into categories that are specifically tailored to the construction industry, outdoor pursuits or sports. Of course, the Google Play Store is also available. We could not find any information about an update to Android 8.0 Oreo though.
Communication and GPS
Only a slow b/g/n WLAN adapter is available in our test device. This means that the S31 only achieves below-average transmission rates, but it is still able to place itself in the mid-range of the comparison devices. The situation is slightly better with mobile radio reception. This smartphone can cope with almost any network, with 4G availability depending on the region. There is an extra model for the North American region. The reception is fine in all networks and the voice quality is very good. We particularly liked the speaker for hands-free talking. Volume and sound quality are also suitable for louder environments.
| Networking | |
| iperf3 transmit AX12 | |
| Nomu S30 | |
| Blackview BV8000 Pro | |
| CAT S31 | |
| Samsung Galaxy XCover 4 | |
| AGM A8 | |
| iperf3 receive AX12 | |
| Nomu S30 | |
| Blackview BV8000 Pro | |
| Samsung Galaxy XCover 4 | |
| CAT S31 | |
| AGM A8 | |
The GPS receiver of the S31 offers a relatively accurate location determination in open air. Only with jagged curves and abrupt changes of direction does the distance recording become somewhat inaccurate. At the end of our test track, the smartphone measures only 20 meters less than the Garmin 500 navigation device.
But the S31 does not only rely on GPS, it also uses GLONASS, aGPS and Beidou. In closed rooms, however, this does not change the bad satellite reception. Using the "GPS-Test" tool, our test device only has an accuracy of 80 meters.
Phone Functions and Voice Quality
In the S31, the standard Android phone app is used. The virtual keys are just big enough to be operated while wearing gloves. Called parties clearly understand the person they are talking to and our test device also distinctly reproduces speech. Using the supplied headset, calls can be made clearly and precisely as well.
Cameras
The cameras of the S31 remain at the same level as those of the CAT S40 from 2015. With an 8 MP main and 2 MP front camera, our test device is only below average. Most comparable models offer at least 13 megapixels.
Even in poor lighting conditions, the main camera can take suitable pictures. However, a steady hand is absolutely necessary, otherwise noise and blurred edges can be seen on the photos. As a webcam, the 2-MP front camera is barely usable. Colors appear very pale and the camera can only transmit movements properly in very good light.
With the main camera, the S31 does not match any color of our ColorChecker Passport perfectly. Light colors are displayed too dark and dark colors are too bright. However, objects in the center of the image are sharply displayed. Borders and structures are visible even with reflections. A slight blurring occurs at the edges of our test images.
Accessories and Warranty
The scope of delivery of the S31 includes a headset in addition to the power supply. Some accessories are also available on the manufacturer's website. In addition to a car mount, car charger cable and a leather holster, Catphone also offers a rugged power bank in the style of robust outdoor smartphones. With a capacity of 10,000 mAh, it has two-and-a-half times the battery capacity of the S31.
Please see our Guarantees, Return Policies and Warranties FAQ for country-specific information.
Input Devices & Operation
Using the virtual keyboard, the S31 offers the usual range of functions of an Android system. Rotations of the device are carried out with a slight delay, but they do not interfere with general operation. The virtual keys are not easy to hit on the small display, even in the horizontal view. The input of long texts could be a stressful task, especially when wearing gloves. The touchscreen responds very well to touch. The system is also directly suitable for operation with gloves. The physical keys sit firmly in the case of the S31 and create the impression that they can be pressed very firmly. The triggering behavior is direct and the feedback from the buttons is also fine.
Display
Catphone equips the S31 with an IPS display which displays screen content at a resolution of 1280x720 pixels. With a screen diagonal of only 4.7-inches, this resolution is sufficient and pixelated edges can only be detected with very close inspection. Corning Gorilla Glass 3 is designed to protect the display. We took a risk and dropped the S31 several times, sometimes at waist height, sometimes from a position in front of the chest. Our test device could parry every fall without scratches. It did not matter whether the fall occurred on tiled floors or pavement slabs. The display of the CAT S40 could not withstand a fall.
| |||||||||||||||||||||||||
Brightness Distribution: 92 %
Center on Battery: 784 cd/m²
Contrast: 1742:1 (Black: 0.45 cd/m²)
ΔE Color 4.28 | 0.5-29.43 Ø4.91
ΔE Greyscale 6.1 | 0.5-98 Ø5.2
98.1% sRGB (Calman 2D)
Gamma: 2.49
| CAT S31 IPS, 1280x720, 4.7" | AGM A8 IPS, 1280x720, 5" | Nomu S30 IPS, 1920x1080, 5.5" | Blackview BV8000 Pro IPS, 1920x1080, 5" | Samsung Galaxy XCover 4 IPS, 1280x720, 5" | CAT S40 IPS, 960x540, 4.7" | |
|---|---|---|---|---|---|---|
| Screen | 4% | -33% | -64% | -36% | -8% | |
| Brightness middle | 784 | 356 -55% | 423 -46% | 434 -45% | 445 -43% | 607 -23% |
| Brightness | 750 | 343 -54% | 421 -44% | 414 -45% | 437 -42% | 579 -23% |
| Brightness Distribution | 92 | 93 1% | 93 1% | 86 -7% | 88 -4% | 90 -2% |
| Black Level * | 0.45 | 0.21 53% | 0.26 42% | 0.64 -42% | 0.67 -49% | 0.5 -11% |
| Contrast | 1742 | 1695 -3% | 1627 -7% | 678 -61% | 664 -62% | 1214 -30% |
| Colorchecker dE 2000 * | 4.28 | 3.7 14% | 7.8 -82% | 9.8 -129% | 6.5 -52% | 4.25 1% |
| Colorchecker dE 2000 max. * | 8.75 | 8.3 5% | 14.5 -66% | 19.2 -119% | 10.6 -21% | |
| Greyscale dE 2000 * | 6.1 | 1.9 69% | 9.8 -61% | 9.9 -62% | 7.2 -18% | 4.09 33% |
| Gamma | 2.49 88% | 2.5 88% | 2.32 95% | 2.64 83% | 2.53 87% | 2.61 84% |
| CCT | 7175 91% | 6412 101% | 9828 66% | 9219 71% | 8274 79% | 6959 93% |
| Color Space (Percent of AdobeRGB 1998) | 71.2034 | |||||
| Color Space (Percent of sRGB) | 94.1292 |
* ... smaller is better
Screen Flickering / PWM (Pulse-Width Modulation)
| Screen flickering / PWM not detected |  | ||
In comparison: 53 % of all tested devices do not use PWM to dim the display. If PWM was detected, an average of 8705 (minimum: 5 - maximum: 343500) Hz was measured. | |||
Measurements confirm our subjective impression of the S31. Especially the outstanding brightness value provides an easily legible image outdoors and in sunny conditions. In combination with the good contrast, our test device only has to surrender to the overall display rating of the AGM A8, although the outdoor phone from AGM can only offer a considerably lower brightness value.
While the resolution of the S31 is lower than those of the comparable devices, screen content is displayed sharply. The slightly increased black value has no noticeable influence on the color representation. All in all, we received a positive impression of the display.
Display Response Times
| ↔ Response Time Black to White | ||
|---|---|---|
| 24.4 ms ... rise ↗ and fall ↘ combined | ↗ 13.6 ms rise |  |
| ↘ 10.8 ms fall | ||
| The screen shows good response rates in our tests, but may be too slow for competitive gamers. In comparison, all tested devices range from 0.1 (minimum) to 240 (maximum) ms. » 54 % of all devices are better. This means that the measured response time is worse than the average of all tested devices (20.9 ms). | ||
| ↔ Response Time 50% Grey to 80% Grey | ||
| 42 ms ... rise ↗ and fall ↘ combined | ↗ 21 ms rise |  |
| ↘ 21 ms fall | ||
| The screen shows slow response rates in our tests and will be unsatisfactory for gamers. In comparison, all tested devices range from 0.165 (minimum) to 636 (maximum) ms. » 64 % of all devices are better. This means that the measured response time is worse than the average of all tested devices (32.8 ms). | ||
Especially outdoors, the S31's display shines. This is not because of the glass surface, but because of its excellent visibility. Screen content is clearly visible from every angle and in all conceivable lighting conditions. None of the outdoor smartphones tested by us can even reach close to the brightness of our test device.
Performance
The S31 is a purely practical device. The Qualcomm Snapdragon 210 MSM8909 with Adreno 304 as the graphics unit is over two years old and was only used as an entry-level SoC in 2015. However, with 2 GB of memory, Android 7.1 Nougat runs smoothly and for the intended purpose no more performance is required.
Compared to its rival devices, the S31 achieves below-average results. With regard to the CAT S40 in particular, it is clear that the current model would only be classified as an entry-level model in 2015.
| AnTuTu v6 - Total Score (sort by value) | |
| CAT S31 | |
| AGM A8 | |
| Nomu S30 | |
| Blackview BV8000 Pro | |
| Samsung Galaxy XCover 4 | |
| PCMark for Android | |
| Work performance score (sort by value) | |
| CAT S31 | |
| AGM A8 | |
| Nomu S30 | |
| Blackview BV8000 Pro | |
| Samsung Galaxy XCover 4 | |
| CAT S40 | |
| Work 2.0 performance score (sort by value) | |
| CAT S31 | |
| AGM A8 | |
| Nomu S30 | |
| Blackview BV8000 Pro | |
| Samsung Galaxy XCover 4 | |
| Geekbench 4.4 | |
| 64 Bit Single-Core Score (sort by value) | |
| CAT S31 | |
| AGM A8 | |
| Blackview BV8000 Pro | |
| Samsung Galaxy XCover 4 | |
| 64 Bit Multi-Core Score (sort by value) | |
| CAT S31 | |
| AGM A8 | |
| Blackview BV8000 Pro | |
| Samsung Galaxy XCover 4 | |
| Compute RenderScript Score (sort by value) | |
| Blackview BV8000 Pro | |
| GFXBench (DX / GLBenchmark) 2.7 | |
| T-Rex Onscreen (sort by value) | |
| CAT S31 | |
| AGM A8 | |
| Nomu S30 | |
| Samsung Galaxy XCover 4 | |
| CAT S40 | |
| 1920x1080 T-Rex Offscreen (sort by value) | |
| CAT S31 | |
| AGM A8 | |
| Nomu S30 | |
| Samsung Galaxy XCover 4 | |
| CAT S40 | |
| GFXBench 3.0 | |
| on screen Manhattan Onscreen OGL (sort by value) | |
| CAT S31 | |
| AGM A8 | |
| Nomu S30 | |
| Blackview BV8000 Pro | |
| Samsung Galaxy XCover 4 | |
| CAT S40 | |
| 1920x1080 1080p Manhattan Offscreen (sort by value) | |
| CAT S31 | |
| AGM A8 | |
| Nomu S30 | |
| Blackview BV8000 Pro | |
| Samsung Galaxy XCover 4 | |
| CAT S40 | |
Depending on the browser benchmark used, the result is mediocre to below average. In daily operation, the low performance is not noticeable though. Elaborately designed websites may take a little longer to load. For most Internet activities, the S31 offers enough performance.
| JetStream 1.1 - Total Score | |
| Blackview BV8000 Pro (Crome Version 51) | |
| Nomu S30 (Chrome 57) | |
| Samsung Galaxy XCover 4 (Chrome 58) | |
| AGM A8 (Chrome 58.0.3029.83) | |
| CAT S31 | |
| Octane V2 - Total Score | |
| Blackview BV8000 Pro (Crome Version 51) | |
| Nomu S30 (Chrome 57) | |
| Samsung Galaxy XCover 4 (Chrome 58) | |
| AGM A8 | |
| CAT S31 | |
| Mozilla Kraken 1.1 - Total | |
| Nomu S30 (Chrome 57) | |
| Blackview BV8000 Pro (Crome Version 51) | |
| CAT S31 | |
| AGM A8 (Chrome 58.0.3029.83) | |
| Samsung Galaxy XCover 4 (Chrome 58) | |
| WebXPRT 2015 - Overall | |
| Samsung Galaxy XCover 4 (Chrome 58) | |
* ... smaller is better
Our reference card Toshiba Exceria Pro SDXC 64 GB UHS-II enables the S31 to achieve average read and write rates. This means our test device can at least be placed near the better comparison devices. The internal memory, on the other hand, is accessed much more slowly. The 16 GB flash memory can be expanded to 128 GB with a memory card and installed apps can be outsourced to it.
| CAT S31 | AGM A8 | Nomu S30 | Blackview BV8000 Pro | Samsung Galaxy XCover 4 | |
|---|---|---|---|---|---|
| AndroBench 3-5 | -21% | 65% | 119% | 31% | |
| Sequential Read 256KB | 71.1 | 140.7 98% | 242 240% | 246.4 247% | 181.6 155% |
| Sequential Write 256KB | 62.1 | 69.5 12% | 194.9 214% | 177.1 185% | 73.6 19% |
| Random Read 4KB | 14.28 | 11.44 -20% | 27.99 96% | 52.7 269% | 21.8 53% |
| Random Write 4KB | 14.81 | 3.73 -75% | 8.84 -40% | 15.05 2% | 11.9 -20% |
| Sequential Read 256KB SDCard | 81.8 | 22.01 ? -73% | 36.94 ? -55% | 79.3 ? -3% | 69 ? -16% |
| Sequential Write 256KB SDCard | 59.5 | 20.46 ? -66% | 21.52 ? -64% | 68.7 ? 15% | 55.7 ? -6% |
Games
Qualcomm's built-in Adreno-304 graphics unit is only suitable for modest games. Therefore, users should limit themselves to older or simple games. The older first-person shooter Dead Trigger runs very smoothly on the S31 and can also be easily handled on the small screen. The touchscreen reacts reliably to inputs. Recent casual games such as South Park: Phone Destroyer also run smoothly and load quickly. In the active game, however, there may be small lags. The outdoor phone is therefore also suitable for the occasional gaming session.
Emissions
Temperature
During idle and in everyday operation, the S31 remains cool. Surface temperatures rarely exceed 30 °C, with the hotspots on the front of the unit. Our test device heats up noticeably under load but does not get hot.
(+) The maximum temperature on the upper side is 36.4 °C / 98 F, compared to the average of 35.1 °C / 95 F, ranging from 21.9 to 63.7 °C for the class Smartphone.
(+) The bottom heats up to a maximum of 33.9 °C / 93 F, compared to the average of 33.9 °C / 93 F
(+) In idle usage, the average temperature for the upper side is 28.8 °C / 84 F, compared to the device average of 32.8 °C / 91 F.
Speakers
A clear, powerful sound is provided by the S31 speaker. The volume is subjectively sufficient to produce audible sounds even in louder environments. According to our measurements, the maximum volume is only moderate. In addition, our test device lacks basses. Since these are relatively flat, there is no abrupt loss of sound. The slightly muffled sound of the loudspeaker also compensates for the missing bass.
CAT S31 audio analysis
(±) | speaker loudness is average but good (76.9 dB)
Bass 100 - 315 Hz
(-) | nearly no bass - on average 21.7% lower than median
(±) | linearity of bass is average (7.8% delta to prev. frequency)
Mids 400 - 2000 Hz
(±) | higher mids - on average 7% higher than median
(+) | mids are linear (6.8% delta to prev. frequency)
Highs 2 - 16 kHz
(±) | higher highs - on average 6.5% higher than median
(+) | highs are linear (4% delta to prev. frequency)
Overall 100 - 16.000 Hz
(±) | linearity of overall sound is average (26.6% difference to median)
Compared to same class
» 65% of all tested devices in this class were better, 6% similar, 29% worse
» The best had a delta of 12%, average was 37%, worst was 134%
Compared to all devices tested
» 80% of all tested devices were better, 4% similar, 17% worse
» The best had a delta of 4%, average was 25%, worst was 134%
Apple iPhone X audio analysis
(+) | speakers can play relatively loud (85.3 dB)
Bass 100 - 315 Hz
(±) | reduced bass - on average 14.9% lower than median
(±) | linearity of bass is average (9.4% delta to prev. frequency)
Mids 400 - 2000 Hz
(+) | balanced mids - only 3.4% away from median
(+) | mids are linear (5.1% delta to prev. frequency)
Highs 2 - 16 kHz
(±) | higher highs - on average 7.3% higher than median
(+) | highs are linear (4.6% delta to prev. frequency)
Overall 100 - 16.000 Hz
(±) | linearity of overall sound is average (19% difference to median)
Compared to same class
» 20% of all tested devices in this class were better, 9% similar, 71% worse
» The best had a delta of 12%, average was 37%, worst was 134%
Compared to all devices tested
» 41% of all tested devices were better, 8% similar, 51% worse
» The best had a delta of 4%, average was 25%, worst was 134%
Frequency diagram in comparison (checkboxes above can be turned on/off!)
Energy Management
Power Consumption
In comparison, the S31 is a relatively efficient device. Especially under load, it achieves the lowest consumption rate of all comparable devices. In idle mode, however, the measurement result is only good enough for a medium ranking.
| Off / Standby |   0.21 / 0.33 Watt |
| Idle |  0.73 / 2.21 / 2.25 Watt |
| Load |
2.99 / 4.12 Watt |
    
| |
Key:
min: ,
med: ,
max: Metrahit Energy | |
| CAT S31 4000 mAh | AGM A8 4050 mAh | Nomu S30 5000 mAh | Blackview BV8000 Pro 4180 mAh | Samsung Galaxy XCover 4 2800 mAh | CAT S40 mAh | |
|---|---|---|---|---|---|---|
| Power Consumption | -23% | -27% | -16% | -4% | -24% | |
| Idle Minimum * | 0.73 | 0.86 -18% | 0.93 -27% | 0.85 -16% | 0.56 23% | 1.2 -64% |
| Idle Average * | 2.21 | 1.97 11% | 2.31 -5% | 1.56 29% | 1.57 29% | 2 10% |
| Idle Maximum * | 2.25 | 2.04 9% | 2.35 -4% | 1.67 26% | 1.68 25% | 2.1 7% |
| Load Average * | 2.99 | 4.86 -63% | 4.57 -53% | 4.37 -46% | 4.6 -54% | 4.3 -44% |
| Load Maximum * | 4.12 | 6.43 -56% | 6.1 -48% | 7.06 -71% | 5.92 -44% | 5.3 -29% |
* ... smaller is better
Battery Life
Our test device delivers superior battery life. Almost 18 hours in a wireless LAN with the display switched on and active browser is a very good performance. None of the comparable devices achieved a similarly high value. The standby time is accordingly longer. In everyday life, the battery lasts for almost a week with moderate use of the device. However, we did not check the 30-day standby time promised by the manufacturer.
If the battery life of the S31 is not enough, you can order a suitable 10,000 mAh powerbank in the Catphone shop for 55 Euros (~$66).
| CAT S31 4000 mAh | AGM A8 4050 mAh | Nomu S30 5000 mAh | Blackview BV8000 Pro 4180 mAh | Samsung Galaxy XCover 4 2800 mAh | CAT S40 mAh | |
|---|---|---|---|---|---|---|
| Battery Runtime | ||||||
| WiFi v1.3 | 1074 | 654 -39% | 832 -23% | 688 -36% | 668 -38% | 611 -43% |
Pros
Cons
Verdict
In our tests, the CAT S31 proves to be the device that the manufacturer promises: A rugged smartphone that can cope with almost any environment. The fact that the technical internals are not up to date with the latest developments can be accepted, but potential customers could choose the far cheaper competitor AGM. As a pure smartphone, the S31 is an entry-level device with a stable system and solid performance. Simple apps and browser activities are no problem with the device. If you like, you can even control it in gloves.
The CAT S31 is a solid smartphone whose main task is not to break. It achieves this in any case, but users have to do without demanding applications.
Buying such a robust device is often a gut decision. Certifications and rough, angular designs are offered by all suppliers of such devices. Whether the CAT S31 can really withstand the most extreme conditions can only be seen through an endurance test in the respective application area of its user. The S31 makes a very solid impression on us, but the high price cannot be justified by the performance and the case alone.
CAT S31
- 12/29/2017 v6 (old)
Mike Wobker
Price comparison
