PAUL OCKENDEN
Paul untangles the world of wireless and looks at how Android is now fronting all manner of devices, including a lightweight projector.
If I think back to the tech in homes and offices a few years ago, one of my overriding memories is wires. Behind every TV set you’d find electronic spaghetti, and you’d discover much the same in the corner of every office. Things have moved on. The wires are still there, of course, but they’re gradually decreasing as more of our gadgets become wireless.
That tangle behind the TV hasn’t disappeared, mind – it too has become wireless, as our homes and offices are flooded with a congested jumble of RF signals. And trying to get a reliable Wi-Fi connection is much like it used to be when trying to find a spare socket to plug in your latest gadget.
I’ve written quite a bit over the years about various tools you can use to monitor and optimise your wireless networks. In particular, I’m a huge fan of Metageek’s Wi-Spy RF receiver dongles and Chanalyzer software (despite the cheesy name). Slightly cheaper is its inSSIDer Essential bundle, which offers the dongle and a slightly cut-down version of the software – it’s still great. You can use inSSIDer without a dongle, just relying on the network card in your laptop, but it isn’t as flexible since it will only detect Wi-Fi traffic. If there’s something else stomping all over the Wi-Fi bands then you won’t know about it without an external receiver.
For 2.4GHz use there’s a much cheaper option, although it isn’t in the same league. For around £12 from UK sellers, you can buy an inch-square board that has an OLED display on the front and an Arduino board sitting behind it running spectrum analysis software. To find it, search for “Lantian spectrum analyzer” (with a z!). It’s based on a homebrew project that first appeared on the RC Groups forums ( pcpro.link/287ard), but as you’ll see from that discussion, the original designer isn’t overly bothered by the fact that a Chinese company is now selling a product based on his design and software.
The tiny board will work with anything between 5 and 16 volts, and it comes with a two-pin JST power socket of the type commonly used by radio-controlled models. I simply bought a 4 x AA battery holder with the requisite plug already attached for a couple of quid from a model shop.
Plug the battery into the Lantian module and you’ll instantly get a real-time display of the 2.4GHz spectrum used by Wi-Fi, Zigbee, and various other devices. You’ll find that it’s devices such as speakers, headphones and baby monitors that can kill Wi-Fi. Many such devices aren’t even legal to sell in the UK. But walk around with the Lantian board in your hand and you’ll quickly locate sources of 2.4GHz interference. Oh, and then switch on your microwave oven and scare yourself with the amount of interference it produces. Don’t worry, it won’t be enough to cook you, but you’ll see exactly why microwave ovens can have a detrimental effect on Wi-Fi performance.
Since the device is based on the Arduino sketch in the forum thread
that I linked to above, you can actually play with the code to adjust the display speed and averaging calculation used, for example. However, at the heart of the device is the nRF24L01+ module from Nordic Semiconductor, which means that you can’t update this little scanner to cope with different frequencies. It’s strictly a 2.4GHz device.
If you need a portable spectrum analyser with greater flexibility, RF Explorer remains my go-to device. I’m now on my third model. I started off with the original device, which covered 240-960MHz. At the time that was useful, because not much happened above those frequencies. There were no 3G or 4G mobile phones back then. But then along came an upgraded model, the 3G Combo, which included two receivers. The original one still covering 240960MHz and a new wide-band board that went from 15MHz to 2.7GHz.
It might seem odd to keep the old receiver when the new board also covered those same frequencies, but the older one was more sensitive so was still useful. I sold my original RF Explorer and bought the (then) new 3G Combo model instead. And I’ve used it many times since. For example, when Mrs O found that the central locking on her car wasn’t working at home but was fine elsewhere, I was able to track it down to a firmware update on my Smappee energy monitor causing a signal repeater to go into a loop and flooding the neighbourhood with 433MHz! It would have been impossible to find that problem without the RF Explorer.
The latest model is the 6G Combo. This time it does dispense with the original receiver, and includes boards covering 15MHz-2.7GHz and 4.85GHz-6.1GHz. This is useful, because it covers both 2.4GHz and 5GHz Wi-Fi bands.
I asked Ariel Rocholl, the designer of the RF Explorer, whether there was an upgrade path from the 3G Combo to the 6G Combo. He said that, unfortunately, there isn’t because the base board is different in each model. However, he did suggest that I could buy a 6G model (non-combo) that covers 4.85GHz-6.1GHz, and then move the 15MHz-2.7GHz from my 3G Combo into the new device to turn it into a 6G Combo.
That sounded like a good plan. I bought the 6G model from EXP Tech in Germany ( pcpro.link/287exp). Not only does EXP sell the device cheaper than the usual UK suppliers, it also offers a fantastic range of products for us IoT, Raspberry Pi and Arduino enthusiasts. The owner, Yuan Wang, is knowledgeable and friendly too. Don’t worry about the language barrier – most of the website has been translated into English, and Yuan and his team speak the language well.
I did swap the boards over, as Ariel suggested, but after a while I switched them back again. I have a certain fondness for the 3G Combo model, and was used to how it works. From now on I’ll carry both devices.
Incidentally, I asked Ariel about the coverage gap between 2.7GHz and 4.85GHz, because much of the upcoming UK 5G mobile coverage will utilise the 3.4GHz bands formerly used by the Ministry of Defence. Ariel told me: “We’re working on additional models to cover 50KHz to 6,100MHz with no gaps, hopefully before the end of the year, at usual price ranges for RF Explorer products. 5G is a big move in the industry and covering frequency gaps is important, but it’s challenging to do so and keep product costs down.”
Projecting the right image
Have you noticed how Android is no longer just an OS for phones and tablets? There are the official offshoots, such as Android Auto for cars and Android Wear used in watches and other wearables, but Android now goes way beyond these!
To take an extreme example, Samsung has a fridge-freezer that runs the company’s Tizen OS (a close relative of Android – Tizen will run many Android apps). It’s one of those American-style two-door jobs, with one of its doors housing a huge touchscreen; it looks just like a massive phone. Then there’s Nikon with its attempts at using Android as the main interface on a compact digital camera (the original S800c was a bit of a dog, and the “improved” S810c follow-up was only slightly better).
And let’s not forget Android-based smart TVs. There’s a plethora available, from high-end brands such as Sony and Samsung, through to a host of cheaper brands that you’ll never have heard of. The ever-increasing cost of subscription TV means various Android-powered Kodi boxes also sit beneath many a TV.
Over the past year or so, another class of Android-based device has started gaining popularity: projectors. It makes sense, because Android works best on devices that already have some kind of display, which is the reason items such as fridges can feel a bit clunky.
I recently started to look more seriously at Android-based projectors, because I was asked to recommend a portable projector to an author friend who could take it to his West Country bolt-hole, but bring it back home when he returned. I was keen to investigate: “domestic” portable projectors have a huge overlap with a certain type of business use too.
When visiting a prospective client, many people assume that they’ll be shown into a fancy boardroom with leather chairs, expensive table and a high-tech screen setup. But trust me, the day will come when the boardroom is in use by someone more important (it’s called boardroom for a reason), and so you’ll end up having to give your presentation in a cramped meeting room or office that’s the size of a cupboard. One with no screen or projector.
“Android is no longer an OS just for phones and tablets. Samsung has a fridge-freezer that runs a close relative of Android”
When this happens, the usual thing seems to be for everyone to crowd around a laptop, but that’s hardly professional, especially if you’re trying to win a pitch for a big new contract. It’s so much better if you can magically pull a projector from your bag and start using it – prospective clients seem to love that. But such a projector needs to be both small and bright.
A few years back, the only option would have been a projector with a halogen lamp. However, these suffered some serious fragility problems, especially if you moved them immediately after a presentation whilst the bulb was still hot. And, of course, you wouldn’t know you’d killed the unit until the next time you tried to use it! Somewhere in my junk cupboard, I still have one of those portable halogen projectors. I got through so many bulbs while lugging it around that I eventually began to carry a spare lamp, along with the screwdrivers needed to disassemble it!
These days, most portable projectors use LEDs, and are very robust. The first generation of LED projectors weren’t particularly bright, but things have moved on. But the brightest LED projectors also tend to be quite bulky, and so aren’t what’s needed here. My author friend wants a unit he can easily carry on the train, so a “beast” is out of the question. The same is true for the business case outlined above – you need a device that you can just pull from your bag if needed, but one that won’t weigh you down if you don’t.
The sweet spot for portability versus brightness seems to be around 600 lumens. Now, to those of you with fancy home-cinema systems, this will seem ridiculously dim, but remember that for PowerPoint presentations and the like, you don’t need the same level of screen brightness as you would for watching a Hollywood blockbuster. Also, the brightness of the projected image will depend on how wide you stretch it – remember, the projector brightness requirement squares with screen size. An 8ft-wide screen has four times the area of a 4ft-wide screen, so needs four times as many lumens for the same brightness. Keep the picture to the size of a large TV (46in, say – but there isn’t even room for that in my friend’s cottage) and draw the curtains and you’ll find that a 600 lumens projector will be fine.
There’s lots of choice in this part of the market, but one device that caught my eye was the Qumi Q38 from Vivitek. Many of the projectors on offer come from no-name manufacturers, but Vivitek has been making projectors for more than a decade, so I got one in to have a play.
Let’s start with the size, because regular readers will know how much I love my little gadgets. The Q38 is pretty much the same size as a VHS tape, if you’re old enough to remember one of those. For you young ’uns it’s just 188 x 118 x 34mm, and weighs 750g. That really is tiny considering the specs. Not only does that little package contain the projector and a speaker, it also has an internal rechargeable battery that’s good for a couple of hours. This is especially important in an emergency meeting room scenario, where the last thing you want to be doing is scrabbling around under a desk looking for power sockets.
The Q38 has built-in Wi-Fi and Bluetooth, and includes around 5GB of usable internal storage, if you want to pre-load content. The 1080p picture quality is superb, and it has automatic keystone adjustment whereby the projector detects how much you have it tilted and will adjust the picture automatically to keep it square. You can switch this off by using the comprehensive on-screen menu.
Best of all, though, it has an Android-based operating system, so you can easily add apps such as iPlayer, Netflix and YouTube. It’s based on Android 6 (Marshmallow) – and, if I’m honest, it’s a bit clunky in places and isn’t as well integrated into the hardware as it could be. Android is unable to report on the battery status, for example, and the firmware update function would often fail. In some respects the Android functionality feels a bit of a last-minute bolt-on, which is a shame. But once you’re familiar with its idiosyncrasies, it works okay.
Those criticisms aside, I think the Qumi Q38 is a brilliant little projector: very well made, super-portable, and equally suited to small-room domestic use or emergency business meetings. And unlike those halogen projectors of old, the bulb in the Qumi Q38 is good for around three and half years of continuous use!
I love gadgets such as this. To be able to pull a paperback-sized box from your bag and watch Game of
Thrones in 1080p on a nearby white wall (or, indeed, present your latest sales pitch) is just brilliant!
“The first generation of LED projectors weren’t particularly bright, but things have moved on”