Aalborg

Aalborg

After a brief look at the Aalborg website, here are the stats that they quote on their site. There's a link to the manufacturer (a Danish comany called Devitech - http://www.devitech.dk).

The camera was a digital CMOS chip based camera based on a Kodak 1.3 Megapixel kac1310.

It had a field of view of roughly 150 km by 115 km, and a resolution of 1280 x 1024 pixels. The colour depth was 24 bits.

The lens in front of the CMOS camera chip was handmade with a diameter of 2 cm and a length of 5 cm.

Based on this information (all available on http://www.cubesat.auc.dk), there are a few simple calculations that I have made.

For example, assuming that the longer side of the array corresponds to the longer field of view, the resolution of the ground per pixels can found as shown:

Resolution = ground covered / number of pixels

Longer side resolution = 150 km / 1280 pixels = 117.2 m.pixel-1
Shorter side resolution = 115 km / 1024 = 112.3 m.pixel-1

These are based on data that was given as approximate, so obviously the degree of accuracy is more like 110-120 metres shown per pixel.

The total number of pixels on the array = 1280 x 1024 = 1,310,720 pixels.

With a colour depth of 24 bits per pixel (giving 224 = 16,777,216 colours?!), so assuming this is true, one single image would require 31,457,280 bits. Thats 3,932,160 bytes, which is 3840 kilobytes which in turn is 3.75 Megabytes per picture. Don't know if this is right, because 24 bit seems an extreme number of options for each pixel, but that is what the data says.

Devitech

Here are the links to each of the CMOS sensor boards that Devitech offer:

Sensor Board Type Width (inches) Colour/Monochrome Price (£) Power Req (mW) bits Temp range (oC) Mass (g) Frame rate (fps) Mega pixels Pixel output rate MHz Pixel size (microns) Area (pixels)
CSB-CM041 CMOS 1/3 Colour 129.35 320 10 or 12 -40 to 85 60 26.6 6.0 x 6.0 752 x 480
CSB-MM041 CMOS 1/3 Monochrome 106.76 320 10 or 12 0 to 70 12 60 6.0 x 6.0 752 x 480
CSB-CM301 CMOS 1/2 Colour 111.96 420 10 0 to 70 13 12, 20, 27, 93 3 48 3.2 x 3.2 2048 x 1536
CSB-CC141 CCD 2/3 Colour TBD 12 0 to 70 TBD up to 20 1.4 28.64 6.45 x 6.45 1360 x 1024
CSB-MC141 CCD 2/3 Monochrome TBD 12 0 to 70 TBD up to 20 1.4 28.64 6.45 x 6.45 1360 x 1024
CSB-MM131 CMOS 1/2 Monochrome 425 10 0 to 70oC 13 30 1.3 48 5.2 x 5.2 1280 x 1024

Prices on site were quoted in either Danish Krone or Euros, so converted to Pound Sterling using an exchange rate taken to be 1 Danish Krone = £0.0929888 (11th October 2007).

From the data in the table above, assuming the temperature to go below 0oC, the only sensor board rated for a sub-zero temperature is the first one in the table; CSB-CM041. This also has the advantage of being a colour sensor board, with a high frame rate. The power consumption of 320mW is low compared to other boards on the site. The one draw back is the size of chip (in pixels) compared to the others. It being smaller, but then this may be an advantage, considering the space required for the nanometeoroid detector. However, the largest space will be taken up by the lens optic, which I have not as yet looked into. Unfortunately, there was no data for the mass of the sensor, but looking at other data for the other sensor board, which are larger, the mass is probably no greater than 13g.

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