Thermal FPV Cameras: How They Work and How Caddx Thermal IRC-640CA Differs from an Ordinary Camera

How a thermal camera differs from an ordinary camera

Values follow this order: Ordinary analogue camera / Thermal camera.

• What forms the image: Visible light reflected or emitted by objects / Thermal radiation emitted by surfaces
• Need for external lighting: Works with available light / No external lighting needed
• What the frame shows: Brightness and color of surfaces / Temperature differences between surfaces
• Through walls, metal, concrete: Cannot see / Cannot see [3]

An ordinary FPV camera works with visible light, which is why more sensitive Starlight-sensor models are used in the dark - such cameras are compared in “As Daylight Fades”. A thermal camera is a separate class of equipment with its own detector.

Caddx Thermal IRC-640CA specifications

• Resolution: 640 × 512
• Detector: Uncooled VOx
• Pixel pitch: 12 μm
• Spectral range: 8–14 μm (LWIR)
• NETD: ≤40 mK @ F1, 25°C
• Frame rate: 50 Hz
• Lens: 9.1 mm, F/1.0
• Video output: PAL, analog
• Power: 5–16 V
• Power consumption: ≤1.5 W
• Operating temperature: −20°C…+60°C
• Size: 27 × 37 × 40 mm
• Weight: 60.5 g
• Price (retail): 28 400 ₴
• Batch pricing: Calculated individually

What these specifications mean

640 × 512. The array has 640 pixels horizontally and 512 vertically - 327 680 pixels. The video output is analog (PAL), so the final detail on screen also depends on the rest of the video path: transmitter, receiver and display.

Uncooled VOx. Uncooled thermal detectors are microbolometers: absorbed infrared radiation changes the temperature of the sensing element and therefore its electrical resistance. Vanadium oxide (VOx) is one of the two main materials for such arrays [1]. “Uncooled” means the detector does not need separate cooling.

8–14 μm (LWIR). This is the long-wave infrared range in which such detectors work [1]. Visible light lies outside it.

NETD ≤40 mK. NETD is the smallest temperature difference the camera can distinguish from its own noise. A lower value means higher sensitivity, and it depends on measurement conditions, which is why the specification states “@ F1, 25°C” [2]. “≤40 mK” means the value does not exceed 40 mK.

50 Hz. The frame rate according to the product specification is 50 Hz.

9.1 mm, F/1.0. A lens with a 9.1 mm focal length and an F/1.0 aperture. The field of view is not stated on the product page, so it should not be assumed.

5–16 V, ≤1.5 W. The supply range is narrower than for the visible-light cameras in the FPV Vision range (for example, DC 5–27 V for FPV Starlight JS-18Por), so check it against your build’s supply.

What a thermal camera can and cannot show

A thermal camera shows temperature differences between surfaces in the frame, not what the eye sees. If the temperature contrast is small, details may be hard to make out; text, colors and fine visual features are not rendered by such a camera.

A thermal camera does not see through walls, metal, concrete or other dense obstacles - the product page says so directly. For infrared radiation glass behaves like a mirror, so the camera will not show what is behind it [3].

The Caddx Thermal IRC-640CA product page lists these scenarios: complete darkness, search and inspection tasks, and work with thermal contrast.

Compatibility: what to check

The video output is analog PAL, so the receiver, goggles or monitor and DVR must support PAL. This is covered in “PAL vs NTSC in FPV Cameras”.

The 5–16 V supply range, ≤1.5 W consumption, 60.5 g weight and 27 × 37 × 40 mm size should be checked against your platform in advance. General principles for choosing and comparing cameras are in “How to Choose an FPV Camera: TVL, Lux, WDR and PAL/NTSC”.

Price and ordering

The retail price of Caddx Thermal IRC-640CA is 28 400 ₴. Batches are calculated individually: send a request with the quantity and the task. Specifications and price are on the Caddx Thermal IRC-640CA page; batch order terms are on the “Wholesale and batch FPV cameras” page.