Casella-cel Nomad portable weather station Manual de usuario descargar pdf (Pagina 60)

one-way communication, with data being transmitted continuously to the PC, as

described in Chapter 4. The default rate is to download at 20 second intervals.

Nomad systems fitted with a Low Power Radio link are delivered

pre-configured ready for use.

The low power radio operates at a nominal frequency 458 MHz, on

eight channels that can be selected by the user. Channel selection is

accomplished by setting a 3 X 3 pin header on the Transmitter Module as

detailed in Table 4.

Table 4: Selection of low power radio channels

These frequencies are those programmed for UK standard MPT1329

license exempt equipment.

8.4.1 Low Power Radio Transmitter Specification

Frequency range 458.5 to 458.6 MHz (8 channels)

Frequency stability ±2 ppm

Number of RF channels RS232 or 1 of 8 parallel select

RF output power

into 50 Ω 100 mW

Adjacent channel power <200 mW (-37 dBm)

TX switching time <60 ms

Modulation input

analogue 200 mV to 5 V p-p AC coupled

digital +3 to 12 V square wave DC coupled

Frequency response 9 Hz to 3 kHz at -3 dB

Deviation with 12.5 kHz

channel spacing ±1.5 kHz nominal (±2.5 kHz max)

Channel switching delay <50 mS across switching bandwidth

Channel spacing 12.5 kHz/20 kHz/25kHz available

Modulation type FID/F2D/F3D

Spurious emissions

conducted & radiated In accordance with ETS/CEPT specifications

Supply voltage 6 - 15 V DC -ve earth

Supply current at 7.2V <100 mA for 100 mW output

Interface connections 2- and 10-pin 0.1" header

RF connection 3-pin 0.1" header

Operating temperature -20°C to +55°C

Storage temperature -30°C to +70°C

Size overall 60 x 39 x 15 mm

2.36 x 1.53 x 0.59 inches

Weight 30 gm

Type approval Designed to meet ETS 300/220 and MPT 1329

Communication

Page 60 of 68

NOMAD Portable Weather Station

Users Handbook

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