Eye-Fi uses Secure Digital (SD) card slot for Wi-Fi in cameras

The power consumed by the Eye-Fi Share card could then be compared, using the same methodology, against the power consumed when storing the picture on a standard SD memory card.

With the camera in standby or turned off, the Eye-Fi card consumed an average of 72 mW while keeping the onboard Wi-Fi in a low-power mode pinging for a Wi-Fi host. Brief power spikes of 585 mW every 60 seconds indicated the Eye-Fi was attempting to keep an active connection with an access point. The standby power consumed by a standard SD memory card was less than 1 mW with a brief spike to 30mW at camera startup.

After taking a picture with the Eye-Fi installed in the DiMAGE Z2, the camera LED, indicating the image was being stored to the 2 GB of NAND memory provided by a Samsung K9LAG08U1M, blinked for approximately 15 seconds while saving the 1.7-MB picture. Data flow from the camera to memory and memory to Wi-Fi is managed by a Hyperstone S4-LDK01 flash memory controller. The average power consumed during the save to non-volatile memory was 170 mW on the Eye-Fi card. The same resolution image stored on a standard SD memory card took approximately 2.5 seconds with an average power consumption of 44 mW--a far lower total integrated power for the simple act of storing an image.

Once the picture was captured and stored in the non-volatile memory, the Eye-Fi manager located in the Windows system tray began blinking indicating communication between the Eye-Fi card in my camera and my laptop. Nineteen seconds later, the image I captured with my camera appeared in a small window on my laptop with a percent bar. According to the status bar, the 1.7-MB image required approximately 39 seconds to transfer from the camera to the laptop at a rate of 45 KB/sec.

Examining the power consumption results from the source measure unit reveals the Wi-Fi chipset, an Atheros AR6001G-BC1E ROCm (Radio-on-a-Chip) mobile WLAN solution combined with an Epic FM2422 2.4-GHz front end module, consumes an average of 160 mW over a 75-second time period (19 seconds setup, 39 seconds WiFi transfer, 17 seconds closing operations) during an image transfer. All ICs, including the memory components, are single-side mounted on a Wintec PCB with a 2007 date stamp. Again this total power consumed for wireless transfer is an additional burden on the camera battery over traditional card-based download.

Jeff Brown is a principle analyst at Portelligent, a TechInsights company. The Austin, Texas firm produces teardown reports and related industry research on wireless, mobile and personal electronics.