Main Technical Specifications; Principles Of Operation - Selcom ST 400 Cayman Operating Manual

1.3. Main Technical Specifications

Range of radiated frequencies
Max. peak radiated power
Antenna polarisation
Operation modes
Sensitivity range in manual mode
Response indication
– visual
– aural
Power supply
Time of operation on one battery charge
Battery charging time
Operating conditions
– working temperature range
– relative air humidity
Weight (with batteries)
Dimensions (length×width×height)
– when folded
– with telescopic arm pulled out completely
Weight of full set in case

1.4. Principles of Operation

ST 402 Cayman is a nonlinear junction detector, or NLJD. Instruments of this type employ
active detection, i.e. they emit probing signals and analyse the return. Their primary search targets
are electronic devices, and those typically consist of circuit plates with conductive elements and
various semiconductor parts connected to them, such as diodes, transistors, and microchips.
The probing electromagnetic radiation induces variable electromotive forces in these loops, and
electronic components with a non-linear current-voltage curve transform the initial signal into its
higher frequency harmonics, which come back to the NLJD's receiver.
Higher harmonics can also be re-radiated by corroded metal or the so-called MOM-diodes,
metal-oxide-metal structures brought about by contacting metal surfaces. However, these
formations return somewhat different spectra than semiconductors.
With ST 402 Cayman one can distinguish with high probability between responses given by
real semiconductors, and those 'faked' by MOM-structures or corrosion. Another important
advantage is a confident detection of search targets behind partially shielding obstacles, which is
achieved by simultaneously radiating several frequencies within the 2-3GHz band and analysing
the composite picture of the reflection spectrum.
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OPERATING MANUAL
2–3GHz
< 2W
elliptic
SEARCH
AUDIO
ADAPT
40dB (5 values with 8dB increment)
three 16-segment LED gauge bars
internal speaker or headphones
two 3.7V rechargeable Li-ion batteries
(type 18650)
3-4 hours, depending on the operation mode
< 3 hours
+5...+40°С
up to 85 percent (at 25°С)
1,75kg
510х145х130
1500х250х130
5,8kg
mm
mm