ATP 4 GB SDHC class 6 memory card

The ATP memory card is specified for reduced industrial temperature range, -25°C – +85°C. Its card reader is specified for commercial temperature range. We had to prove these parameters by checking the speed of the data transfer at certain temperatures.

For this test I used a temperature bath Hart Scientific 7103 (Fluke Company) which has a regulation range from -30°C - +125°C with accuracy of 0.01°C.

Data transfer rate was measured with Total Commander. One big file (1.4 GB) and several small files (totaling approx. 1 GB) were used. The smaller files were pictures ranging in size from 3 to 6Mb. For each of these, I copied them five times to and from memory card and then calculated the average.

Thermal bath with the card in the medium (oil) and the notebook used for transfer measurement (Centrino 1.6GHz, 512Mb, USB 2.0).

For comparison with the ATP card, I used a Kodak 256Mb card with a commercial temperature range which is neither HC nor class 6.

Measurement results

Typical temperatures.

The chart contains the results for each card at a specific temperature:

The results were expected. SD data transfer protocol is a combination of serial and parallel (4 bit parallel – 6 clock cycles are needed to transfer the information of one 24-bit colour pixel), so transfer speed depends on the crystal oscillator frequency. Crystal oscillators have a negative temperature coefficient and their frequency increases when the temperature goes down. But this all happens in a +/- 10 percent range.

ATP memory card is specified as industrial, while the Kodak card was specified as commercial, and there were some differences. When changing the cards in the reader, the Kodak card had to be warmed up to room temperature to be readable. At temperatures below 0°C, the system didn’t recognize the card. After warming it up, the system recognized it, and it could subsequently be cooled down and it worked fine. ATP card was recognized in every condition, even with a visible condensation on it (which is outside the declared specifications). Both cards work outside specified operating temperatures, however, the Kodak card just couldn’t cope with a shock therapy, but it kept the data safe in all conditions. Which, after all, is the most important factor. Our pictures will be retained even if the card is left in the summer sun or in the polar night. The ATP card can be read by the reader at any temperature, but the Kodak card needs to be warmed up first.

If your camera is weatherproof and can use SDHC cards, ATP cards guarantee safe storage and readability of all your pictures.