National Flood Workshop
Houston, Texas
October 2010
ALERT2 PROTOCOL PERFORMANCE
Don Van Wie, Telos Services
R. Chris Roark, Blue Water Design, LLC
ALERT2 IMPLEMENTATIONS

ALERT2 Concentration Protocol is in production
in Overland Park/KCMO for repeater-to-base
path

ALERT2 is operating in parallel with ALERT on
repeater-to-base leg in Urban Drainage and
Flood Control District
STUDIES

UDFCD: ALERT v ALERT2 side-by-side comparisons


8 months, 2 million ALERT messages analyzed
Overland Park: Logging at repeater sites permits
exact determination of ALERT2 losses


Early June storms with partial logging
Full month analysis for September 2010
PURPOSE OF TESTING

Demonstrate reliability of hardware in normal
operating environment

Quantify the relative performance of ALERT/ALERT2

Verify or and adjust the operating parameters based
on operations at a production scale
THE BOTTOM LINE





No hardware failures
ALERT2 data loss “over the air” is typically less than 5
reports per 10,000 over any path that is suitable for
ALERT
Relative ALERT2 performance improves as traffic
rates increase
RF-only Preamble has been extended 55 msec
Slot variance study shows 0.5 second slots are
possible
HARDWARE PERFORMANCE

10 BWD Modulator/Encoders


6.5 years of unit time accumulated
4 BWD Demodulator/Decoders

4.75 years of combined operation

About half of equipment is in unconditioned
environment

NO Failures!
UDFCD OVERVIEW
Data Composition and Summary Statistics
Repeater
Start Date
ALERT Records
Blue Mountain
8/1/2010
328,319
334,064
5,745
1.75%
Smoky Hill
2/23/2010
771,716
781,508
9,792
1.27%
West Creek
2/23/2010
478,256
489,544
11,288
2.36%
Lee Hill
4/9/2010
178,764
183,148
4,384
2.45%
Gold Hill
5/10/2010
250,250
261,083
10,833
4.33%
Total
ALERT2 Records Difference (A2-A)
2,007,305
2,049,347
% Difference
42,042
2.09%
1400
Reports per hour
1200
1000
800
600
400
200
0
2/21
3/23
4/22
5/22
6/21
ALERT
7/21
ALERT2
8/20
9/19
10/19
Messages Lost
ALERT TO ALERT2 DIRECT COMPARISON
1,000
500
ALERT Loss
0
ALERT2 Loss
Blue Mtn
Smoky Hill
ALERT2 Loss
Gold Hill
ALERT Loss
ALERT
Repeater
Alert
%
Missed by
%
Alert
Errors
Lost
Alert2
Lost
25,000
445
1
1.78%
1
0.004%
Smoky Hill 25,000
149
0
0.60%
4
0.016%
25,000
966
5
3.88%
5
0.020%
75,000
1,560
6
2.08%
10
0.013%
Blue Mtn
Gold Hill
Sample Missed by
ALERT2
RECENT OVERLAND PARK PERFORMANCE
12.00%
9.00%
6.00%
3.00%
0.00%
Johnson Co
Blue Valley
Century Twrs
Fire Training Cntr
OP City Hall
Summary of September 1-28, 2010
Century
Tx From: Johnson Co Blue Valley
Twrs
Rpts Sent 72678
101091
120940
OP City Hall
Lost Rpts
2326
2785
2774
% Loss
3.20%
2.75%
2.29%
Fire Training Cntr Lost Rpts
31
75
21
% Loss
0.04%
0.07%
0.02%
Totals/Avg
Totals/Avg
294709
7885
2.68%
127
0.04%
JUNE 8 O.P. STORM ALERT LOSSES
3500
3000
Messages per hour
2500
2000
1500
1000
500
0
14:00
15:00
16:00
ALERT Total
17:00
All Loss
A2 Loss
18:00
19:00
ALERT2 PERFORMANCE IN RAIN EVENT
2500
18.0%
16.0%
14.0%
12.0%
1500
10.0%
8.0%
1000
6.0%
4.0%
500
2.0%
0
12:00
14:00
16:00
18:00
20:00
22:00
0:00
2:00
UDFCD June 11/12, 2010
Traffic Rate
% Improvement
(A2-A)/A
4:00
0.0%
6:00
% Improvement
Messages per Hour
2000
COMPARISON OF LOSSES – JUNE 11-12
ALERT lost 577
ALERT2 lost 11
180
ALERT Messages
160
140
120
100
80
60
40
20
0
20-732
ALERT Loss
21-652
22-708
23-812
ALERT2 Loss
ALERT2 Loss
0-1109
ALERT Loss
1-1189
SMOKY HILL TRAFFIC – ALERT2 ONLY
700
600
Messages per Hour
500
400
300
200
100
0
2/21
4/12
6/1
ALERT2
7/21
9/9
SMOKY HILL TRAFFIC – ALERT ON ALERT2
700
600
Messages per Hour
500
400
300
200
100
0
2/21
4/12
6/1
ALERT2
7/21
ALERT
9/9
ALERT2 PERFORMANCE V TRAFFIC LOAD
40%
35%
30%
25%
20%
15%
10%
5%
0%
500
1000
1500
2000
2500
Traffic Rate - Messages per Hour
Improvement
Modeled loss, 2 per collision
Modeled Loss, 1 per collision
3000
VARIANCE FROM EXPECTED SLOT TIME
0.1
0.08
0.06
0.04
0.02
0
-0.02
-0.04
-0.06
-0.08
-0.1
9/23 00:00
9/23 06:00
9/23 12:00
9/23 18:00
Century
9/24 00:00
Blue Valley
9/24 06:00
JoCo
9/24 12:00
9/24 18:00
9/25 00:00
OUTLIERS IN GPS CLOCK SETTING
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
-0.1
9/23 00:00
9/23 06:00
9/23 12:00
9/23 18:00
Century
9/24 00:00
Blue Valley
9/24 06:00
JoCo
9/24 12:00
9/24 18:00
9/25 00:00
COMING IMPROVEMENTS TO GPS
SYNCHRONIZATION ALGORITHM

To eliminate false setting by anomalous readings:


Limit correction based on plausible drift rate
Lengthen time in lock before taking readings
IMPLICATIONS FOR CHANNEL CAPACITY

Lengthened preamble affects capacity
Affects first block only
 Impact diluted as traffic increases


Size of required deadband controls available slot
time; 100 msec will be adequate
500 msec slots can be used for most gage sites
 Capacity of 1 channel is 120 gages, 331 KBytes/ hour
 2 sec slot (repeater) can carry 630 Kbytes/hour or
157,500 ALERT Messages

WHAT’S NEXT…

Ready for new ALERT Concentrator applications

Low power repeater for 2011

Vendors are working on gage applications

Implementation of Protocol Application layer
Thank you