Look inside one of HP’s new Link-5 compatible devices and explore analog, digital, and RF signals using Oscium’s suite of tools. Use Oscium’s WiPry-Spectrum tool for investigating the 2.4 GHz Wi-Fi signals between keyboard and PC.
The figure above shows Oscium’s wifi spectrum analyzer and a 2nd generation iPod Touch measuring the signal traffic at 2.4 GHz between HP’s new Elite V2 wireless keyboard and its paired computer. HP’s new Link-5 technology lets everyday users connect up to five Link-5 compatible PC accessories with a single receiver. The Link-5 receiver plugs into a single USB port in user’s laptop or desktop PC USB port, freeing the other USB ports for other uses.
Read this attached PDF to learn more about Link-5 connectivity: 
HP_Link_5_Datasheet.pdf
Open Up The Keyboard And Peek Inside
Pictured below is the backside of the HP Elite V2 Wireless Keyboard. With the rear panel removed, you can see the ribbon cable spliced into the keyboard matrix metal structure, the terminals for the two AA batteries, and the keyboard’s processor and RF circuit card assembly. On the other side of the gray metal backing plate, there is an array of capacitive switches and a flexible printed circuit board comprising a grid or mesh-type network of low voltage conductors that keypad matrix. 
How Keyboards Work
If you would like to learn more about how keyboards work – how a processor can decode keystrokes – then you might find this short article interesting. Borrowed from the popular website “HowStuffWorks.com”, this write up briefly summarizes the basic components of keyboards in general, and it describes how a change in the current through the keyboard’s matrix is decoded by the processor using key mapping. http___computer.howstuffworks.com_keyboard4.pdf
Take A Closer Look At The Control Board
The HP Elite V2 keyboard CCA has four sub circuits that will be covered in this blog series. Pictured below, the sub circuits, from left to right, are 1) a 16 MHz crystal oscillator, 2) the system on chip processor, 3) the filtering/matching network, and 4) the 2.4 GHz Wi-Fi antenna.
Click this link to see a full sized image of the control card. Control_card.pdf