JTECH Communications Inc. SERVALERT200 Manuel D’Utilisation

 

Over the years a number radio frequency data patterns (Languages) have evolved to 
“speak” to pagers. POCSAG is the most widely used language today and a language 
that JTECH products support. POCSAG is simply an algorithm that is used to encode 
alphanumeric and numeric data for transmission via modulated radio waves.  

Two types of data may be sent to today’s pagers, either numeric only or alphanumeric. 
Numeric only data is easier to decode and may be received on less costly pagers. 
Alphanumeric data is more flexible than numeric only, but is more difficult (expensive) 
to decode and display and therefore must be received on more expensive pagers. The 
received radio data for Alphanumeric POCSAG messages are different in format than 
numeric only messages and therefore will result in “garbage” being displayed when 
alpha messages are sent to numeric only pagers. The opposite is also true. JTECH 
Communications, Inc. uses a specific descriptor in the format used to “Talk” to its 
transmitters to allow the user to select either alphanumeric or numeric only protocol. 
(This option is only available when using 7 digit extended protocol). The actual 
modulated radio waves sent in alphanumeric messages versus numeric only messages 
are different even though the content may appear the same.  For example, the radio 
waves received by a numeric only pager that is to display the message ‘123’ will be 
quite different than the radio waves received by an alphanumeric pager that is to 
display the message ’123’. 

Radio Frequency baud rates are the rates at which radio transmitters modulate 
radio waves into the “1’s” and “0’s” received by pagers. The most common RF 
baud rate is 512 baud, but 1200 baud and 2400 baud are increasing in 
popularity. JTECH Communications, Inc. uses 512 baud, but our transmitters will 
support 1200 and 2400. Testing to date has shown 2400 baud to be slightly less 
reliable than either 512 or 1200. Faster data rates are used primarily by wide 
area paging services where throughput is a critical concern. For example, at 
peak paging times, a citywide paging service would be able to send four times 
the number of pages by using a 2400-baud rate vs. 512 baud. On-site systems 
simply do not have the traffic to necessitate the use of higher baud rates. The 
observable difference may only be one to one and a half seconds faster with 
2400-baud versus 512 baud. With the higher reliability of 512 baud the 
difference in speed is not enough to offset this reliability difference. JTECH uses 
a specific descriptor in the format used to “Talk” to its transmitters to allow the 
user to select either 512, 1200 or 2400 baud.