SmarTek Systems SAS-1 Detailed Communication Formats User Manual
Page 7
SmarTek Systems (www.smarteksys.com)
7
Chr(2)SASxxxx
All parameters are bytes and are offset by +32 (20 Hex).
T_Det is the max detection threshold byte ( Max Det Threshold (db)=(T_Det - 120)/4.0 ).
Alpha is the smoothing time constant byte (Smoothing constant=Alpha/100).
Spare_2 is a spare parameter place holder byte.
Rpt_Intv is the measurement observation inerval and the periodic reporting interval in seconds.
D_Mode is default operating mode (Note 0).
Monitor_Mode is the monitoring mode (0-Intersection, 1-Freeway) (Set via the Default Op
Mode Command).
InetSw is an Internet Connectivity Switch (0 if internet connection, 5 if hard wire or dedicated
wireless). If InetSw = 0, SAS-1 response timeouts are increased to account for internet delays
and latency.
Comm_Mode is the default communication mode (1-Polled, 2-Periodic).
Network_Number is the radio hopping pattern number (0 to 63).
LCx is each lane/zone center (pixels) and LSx is each lane/zone size (pixels).
AVLx is the average vehicle length for each lane/zone (feet).
OCx is the occupancy calibration factor (Calibration factor=OCx/100).
SNx is detection sensitivity for each lane relative to T_Det ( Sensitivity (db)=(SNx - 120)/4.0 ).
T_Floor is the min detection threshold byte (Min Det Threshold (db)=(T_Floor - 120)/4.0 ).
Add_Noise is an added artificial noise floor byte to reduce SAS-1 sensitivity (Processing Noise
Floor(db) = Actual Noise Floor + (Add_Noise-120)/4.0 ).
Note 0: D_Mode = 0
Simple Flow
1
AzDet
2
Relay
..5 Upstream relays are vehicle presence, 5 Downstream
relays are inactive
3
Not Defined
4
Not Defined
5
Flow with Truck Counts
6 to 95 Reserved for Future Enhancement
96 to 110
Dual Loop Relays
..5 Upstream and 5 Downstream vehicle
presence relays with the equivalent loop separation (in feet)
given by D_Mode-118+32
Command to SAS-1: Send Parameters to SAS-1