The Sony UWP-D Wireless package has been around for a few years now, and is a replacement for Sony's older mid-tier UWP radio mic package. It has most of the same features of the older system (including backward compatibility with that system) but offers a new digital companding mode; more on that in a minute.
Design
The first thing you notice about this new system is the design and build quality. Sony have redesigned the packs, to be more in line with your typical radio mic transmitter, these are smaller and lighter than the old UWP, and the Sennheiser G3 series, while also retaining an all metal housing (but plastic battery sled).
The design is slim and rugged, with a yellow highlight around the screen.
The New
As a relative newcomer to Sony wireless systems, I can't really compare to those, although I have used the Sony DWX digital system once, and the old UWP system once; both just for an afternoon. What I can say is that the UWP-D is a nicer sounding system than the Sennheiser G2 and G3 systems I've predominantly used prior to this. The G2's while great when they came out lack the diversity reception system and use a fairly dated compander. The new digital compander is really the headline here though. A similar system to the "hybrid digital" system in the Lectrosonics high end systems, but delivered at a vastly lower cost. It allows for higher precision, and better handling of fast transient sounds like claps, and the keys test, something that low cost analogue companders could never really achieve.
They sound good enough to be used alongside professional systems from the likes of Audio Ltd, Audio Wireless, Lectrosonics, Wisycom, Zaxcom and the top end Sennheiser and Sony Digital systems. Although you'd probably notice the difference if your used to hearing one of those on a regular basis.
Diversity
The Sony system employs a dual antenna, space diversity system giving improved reception over non diversity systems like the G2 and G3. It however remains a 30mW power transmitter so range remains roughly the same as the Sennheiser G3 system. However, due to the digital compander element, instead of a reduction in audio quality with extended range, what you get on the edge of acceptable reception range is all or nothing. So you either get full quality, or you get nothing at all. This offers improved quality while within range, making the UWP-D system very suitable as a camera link system, especially with it's higher fidelity sound and relatively low noise floor compared to other lower cost analogue compander based systems. (It's also a strong point for other digital systems too.)
Unfortunately the system has fixed antennas, meaning it can't be used in conjunction with antenna distribution systems without modification to SMA connectors, which would void any remaining warranty.
There are also two dual channel receivers in the range, which I don't have yet. There's a Sony camera slot dual channel true diversity receiver with BNC detachable antenna, designed specifically for mounting in Sony broadcast cameras or the Sony made adapter. Also a beltpack style one that operates in dual channel space diversity or single channel true diversity, making use of both receiver circuits for a single channel. It is however a larger unit, probably about 5mm thicker than the standard single channel receiver.
Output
The receiver, alongside its normal mic level output, also has a headphone output. Meaning you can use the receivers as IEM feeds in a pinch. The phones volume is adjusted in a menu rather than a front panel control, but the sound quality is great, and a better reflection of the audio you are mixing/recording than the G2 system I've been using up until now. Another interesting feature of the beltpack style receivers is the Sony MI shoe adapter, which can be used with Sony FS7 & FS5 video cameras, as well as a number of Sony's mirrorless and SLT cameras. The adapter passes audio, and an on/off signal to the receiver. In the case of the full size video cameras it also supplies power to the receivers.
Power
The UWP-D series is powered by standard AA batteries and will run all day on a set of high capacity Ni-MH rechargeables. It also has a microUSB input for powering the packs and for charging those Ni-MH batteries. For us sound recordists it means you can run the packs without batteries in your sound bag using a simple hirose to USB adapter. They're relatively low power consumption too, reducing the number of battery changes you might need in a day.
If you're mounting the receivers on a Sony FS7 or FS5 camera you can also use the MI Shoe for power from the camera, along with the audio feed.
One thing to note here however is that when powering by USB from the same power source feeding your recorder you will introduce noise when using packs at mic level. I typically use these kits as camera links, sending audio from my bag to a camera. It's important to set the transmitters to line level and feed them appropriately, or else you may find yourself with an unacceptable noise floor in the transmission. Switching to line level inputs will correct it. The same seems to go for the receivers too. When powered from USB the mic level output is quite noisy, but the headphone output is clean.
Bundled mic disappointment
The mic that comes bundled with the standard boxed system is sadly a bit of a dud. It sounds a bit dull, even clip mounted, and is too big to be used effectively as a hidden mic. It's a bit big as a clip mic too. I changed my mics to my preferred second hand mic of choice, and am now using Sony ECM-77 mics with my two packs. They're clean, clear and reasonably easy to get hold of second hand.
One minor sort of non-issue with the UWP-D is that the 3.5mm jack is wired differently to that of Sennheiser... meaning mics wired for Sennheiser won't work, without rewiring or an adapter, on the Sony packs. As someone who doesn't mind a bit of soldering I re-terminated some ECM-77's myself, but anyone not comfortable with a soldering iron can get them done by a professional for about £20 per lav mic.
Last words
To conclude, the Sony UWP-D wireless series is a very capable system.
It has great sound quality, is relatively easy to use, has backwards compatibility with older Sony systems and has numerous powering options for modern workflows.
But, the mic that is bundled should probably be binned (or kept as a last resort emergency backup), and the noise introduced at mic level by the USB powering from the same source at the recorder is really unacceptable
I truly believe that this system is better than Sennheisers G3 system. It should be equal or better than the upcoming G4 system too, but the G4 has the bonus feature of a 50mW power mode for extended range, which may prove to be the downfall of the Sony UWP-D system if it doesn't get an upgrade.