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12.2.2. Hearing aids
In rare cases the signal emitted by the telemetry module's antenna may disturb hearing
aids functions. Should that occur, one has to study detailed operating instructions and
recommendations for that particular product.
12.2.3. Other medical equipment
Any radio device including the telemetry module may disturb the work of electronic
medical equipment.
When there is a need of installing telemetry module in vicinity of medical equipment one
has to contact the manufacturer of this equipment in order to make sure that the
equipment is adequately protected against interference of radio frequency waves (RF).
12.2.4. RF Marked equipment
The restriction against installing telemetry modules in areas marked as radio frequency
(RF) prohibition zones must be unconditionally observed.
12.3. Explosive environment
Installation of telemetry modules in the environment where explosion hazard is present
is not permitted. Usually, but not always, these places are marked with warning signs.
Where there is no marking do not install telemetry modules at liquid or gas fuels stores,
inflammable materials stores, nor places contaminated with metal or wheat dust.
13. Appendices
13.1. Data transmission in GSM systems
At the moment, a subscriber to GSM services has 3 technologies of sending data at his
disposal besides voice communication. These are: SMS, CSD and GPRS. Since they offer
different functionalities a short description is necessary.
13.1.1. SMS
„Short Message Service
” - the technology of sending text messages. The length of the
message is 160 characters. Permitted characters are letters and numbers. Despite of its
popularity it is not an optimal service for telemetry. The cost of an SMS is constant
regardless of information length (within 160 characters limit).
In telemetric applications, using the text mode would require dedicated formatting and
special programming for reception. The conclusion is simple. This service was not created
for telemetry applications but may be an attractive supplement.
Suppose that along with monitoring current values, it is possible to receive perfectly
readable textual information containing a warning about alarm situation.
It is quite a useful supplement.
13.1.2. CSD (HSCSD)
„Circuit Switched Data
” - a technology for sending data via commuted communication
channel set up on subscriber demand. Despite using a digital telephony technology the data
transmission is analogical to traditional telephone modem.
The user establishes a connection with a defined subscriber number and carries out a
transmission of data stream sent to the serial port connected to the GSM modem. It is a
point-to-point transmission where only 2 data sources are connected. After transmission,
the connection is broken and the subscriber charged for the time occupying the channel.
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