Teledesign Systems Inc TS4000EH Manuel D’Utilisation

The slot time should be set to the attack time of the radio plus the maximum 
variation (uncertainty) in the carrier detection circuit.  The variation in the carrier 
detection circuit is the difference in the carrier detect time between the radio with 
the fastest carrier detect time and the radio with the slowest carrier detect time.  
Note that the attack time is made up of the worst case transmitter power ramp up 
time plus the worst case carrier detect time. Typically the maximum variation of 
the carrier detect circuit is less than half (50%) of the attack time. 
 
 

 

 
Tx Attack Time is a fixed value that is preset for the radio in the 
TS4000.  This value can be read out of the TS4000 using the 
Retrieve Radio Hardware menu or button.  The Additional Transmit 
Attack Time is the value set on the radio tab of the modem 
configuration. 

 
 
The minimum idle slot setting defines the number of slots which a modem will 
leave vacant after the modem detects an idle channel and before the modem 
attempts to transmit.  A setting of 0 means that the modem will attempt 
transmission in the first slot after the channel becomes available (idle).  A setting 
of 1 means that the modem will wait 1 slot after the channel is available before 
attempting to transmit.  The number of minimum idle slots can be set differently 
for each packet type (data, ACK or relay).   
 
The simplest and most efficient system setup is where ACK (acknowledgment) 
packets are sent immediately after a valid data packet is received.  With this 
setup the ACK packets do not contend for the channel the way data packets do.  
Correspondingly, the data packets are set so that they will leave the first slot 
open for the ACK packets.   
 
This type of setup has the advantage that the delay for receiving an ACK packet 
is consistent and predictable.  This makes it much easier to set an appropriate 
packet timeout (see Setting Packet Timeout). 
 
Min Idle Slots - ACK Packets 

 
For systems with one or more relay nodes, the simplest and most efficient 
system setup is where each relay is assigned a particular slot.  This way the 
repeaters do not collide or contend for the channel the way data packets do.  The 
data packets are set so that they will leave the necessary number of slots open 
for the repeaters and ACK packets.   
 
This type of setup has the advantage that the delay for sending data through the 
relay(s) is consistent and predictable.  This makes it much easier to set an 
appropriate packet timeout (see Setting Packet Timeout). 
 
Min Idle Slots - ACK Packets 

 
Min Idle Slots - Relay #1  

Min Idle Slots