Instruction manual

Model DCP-NextG Digital Cell Phone Kit

6 Power Considerations

6.1 Current Requirements

Because of the transmitting current drain of the Intercel SAM 3G+, the length and frequency

of both incoming and outgoing calls should be considered when determining the best power

supply for your system:

o Where pre-determined call intervals are short and infrequent (e.g.: 10 minutes per

day), the system can typically be powered by sealed rechargeable batteries

supplemented by a charging source (AC power or solar panel)

o For longer calls or more frequent time intervals (e.g.: 20 to 30 minutes every hour), a

deep-cycle battery trickle-charged by AC power would be a better option for powering

the system.

o When communications between the data logger and the computer must be available

for long periods of time, AC power may be required.

Use the current consumption numbers in Specifications (section 2) to calculate the power

consumption of your modem and the size of battery, solar panel and charging regulator that

you will require.

6.2 Switched Power

In an effort to conserve power, power to the modem can be switched on and off at different

times or under certain circumstances by utilizing the Switched 12V supply or by using an

external relay circuit. Details of an external relay circuit can be found in the installation

section of your data logger manual. Common configurations include having the modem

switch on for 10 minutes per hour or switching the modem off during night time in solar

powered systems.

Switched 12V power can be supplied by the data logger on its SW12 channel. Note that this

output is controlled by the datalogger program and is disabled by default – a modem plugged

into an unconfigured data logger’s SW12 will be unpowered. In order to use SW12, the

logger’s program must be written to switch the power on and off using the SW12() instruction

in CRBasic.

6.2.1 SW12 and Remote Program Upload

Please exercise caution when loading new programs over the modem link if the modem is

to lose power and the station may no longer be contactable.

One good way to avoid this situation is to insert a SW12(1) statement in your CRBasic

program between the BeginProg and Scan() statements – this will ensure that one of the first

things the logger will do after receiving its new program is power on the modem.