Hydro Logger H40
User manual
14
electronics for ecology
FIEDLER
3.3.
GSM modem operational status
signalling
The plastic cap of the H40G station contains a signal
LED in addition to the GSM connector, communication
connector and connecting cable. By the speed at which
this LED flashes, the device indicates the current status
of the GSM module.
Tab. 1: Signalling LED.
LED status Meaning of signalling
The LED is not lit
GSM modem is switched off - normal idle state.
Flicker 1 Hz
The GSM modem logs into the network.
Short flash once
every 5 sec.
The GSM modem is logged into the network, no data trans-
fer is taking place.
Fast flashing 2 Hz
Receiving or sending an SMS message
Fast flashing 5 Hz.
Data transfer via GPRS data network
Before data transfer from the station to the server or before sending SMS from the sta-
tion, the modem of the station must be logged into the GSM network. If the GSM signal
is strong enough at the location of the station antenna, the station will be logged into the
network after about 20 seconds from switching on the GSM module (slow flashing of the
LED).
Data transmission to the server can take from a few seconds to 5-10 minutes, depending
on the amount of data transmitted and the quality of the GSM field. During the ongoing
data session, the signaling LED flashes at an increased frequency of 2 Hz.
Forced switching on of the modem during installation of the station can be triggered from
a PC (notebook) connected by cable under the MOST program. The procedure is de-
scribed in the following text.
3.4.
Antenna and its location
The Hydro Logger H40 comes with a small GSM 1dB antenna that
connects to an SMA connector.
Reliable GPRS and SMS communication requires a GSM field strength
of at least 8 on a scale of 0 to 31 at the antenna location. With lower
signal strengths, it may happen that some GPRS data sessions do not
take place at the set time, but only on other days with better conditions
for GSM signal propagation.
When installing the station, it is therefore important to take care of the
appropriate location of the supplied magnetic GSM antenna with re-
spect to the GSM field strength. In most above-ground buildings, the
location of the antenna is not critical and it can be mounted vertically
almost anywhere on a suitable elevated location.
The simplest method of finding a suitable location for the antenna using
a scale on a mobile phone gives only approximate results. Remember
to use the SIM of the same operator that the telemetry set-up will be
using. This method can be used wherever the GSM field strength is
sufficient and no special requirements are placed on the location of the
GSM antenna.
L E D
G S M f i e l d i n t e n s i t y
A b o v e - g r o u n d
o b j e c t s
AGSM-9dB-SMA
