MidTerm Flashcards
(107 cards)
1
Q
What are the three keys to success in Precision Ag?
A
Information, technology and management
2
Q
Precision ag is defined as:
A
A system designed to optimize ag production through crop information, technology and management practices
3
Q
One of the most common starting points for farmers entering precision ag:
A
Swath Guidance
4
Q
The 5 objectives of precision ag are:
A
Energy Conservation Soil/Ground Protection Efficient Chemical Use Improved product Quality Increased Production Efficiency
5
Q
What is Postharvest Control?
A
aspect that addresses the control/protection of product quality shortly after harvest but before delivery
6
Q
What is site specific management?
A
Management of the field by recognizing differences across the field and breaking it into smaller zones
7
Q
What is the farmers most valuable resource?
A
Information
8
Q
What are the 2 tools that make precision ag feasible?
A
GPS and GIS
9
Q
What is Spatial Variability?
A
Changes in measured properties over distance or depth
10
Q
What is active remote sensing?
A
A remote sensing system that generates it’s own signal and monitors for a response
11
Q
What is an embedded computer?
A
Computer designed for a specific purpose, has limited flexibility and software for it’s task
12
Q
What is spatial resolution?
A
The smallest object that can be detected
13
Q
What is temporal variability?
A
Changes in measured properties over time
14
Q
What is physical variability?
A
Changes in measured physical/chemical properties
15
Q
What is Feedback Analysis?
A
Input –> Analyzer –> Output
^ – Feedback ———-|
Continuous improvement due to feedback
16
Q
What is a measurand?
A
Physical parameter of interest in a information system
17
Q
What is a sensor designed to do?
A
Detect change in a quantity and convert it into signal
18
Q
What is a transducer used for?
A
Convert signals into a more useable form
19
Q
What do we use to transport information between systems?
A
USB drives, Wireless transfer, PCMCIA cards
20
Q
What is a coordinate system?
A
A frame of reference from which measurements are made
Specifies units of measure on an axis from an origin
21
Q
What is a geoid?
A
A mathematical model of the earth’s grav field, it is a reference for determining elevation. It roughly corresponds to mean sea level
22
Q
What is georeferencing?
A
The act of turning an image into a map by linking points in the image to coordinates. Need 3 or more points
23
Q
What is GNSS?
A
A space and land based system that allows a receiver to determine location based on the known position of space vehicles
24
Q
What is the highest accuracy GPS?
A
RTK
25
What are L1, L2 and L5
GPS Frequencies
26
Position System Requirements:
Available at any point
Available any time
Should interface with equipment
27
How many satellites are needed to get a GPS fix?
4
28
GPS for civilians is called
SPS, standard point positioning
29
What is a C/A code?
Civilian receivers code
30
What is PPS?
Military GPS, precise point positioning
31
What is trilateration?
Determines the location of the receiver based on estimated distance for the satellite
32
The distance between a sat and a receiver can never be measured exactly
True/False?
True
33
NMEA 0183
Standard that defines GPS serial communications. Includes a baud rate specification (speed of transmission)
34
Most common GPS sentences are?
GLL
GGA
VTG
35
What is 'true range'?
Distance between satellite and antenna
36
What is the unique identifier that a GPS receiver uses to identify which psuedorandom code it is tracking?
PRN
37
The use of 2 frequencies in a receiver allows for correction of:
Ionospheric effects
38
2DRMS means:
95% probability that observations will fall within 2 standard deviations
39
What is PDOP?
Position of Dilution of Precision, a type of error estimate. Less than 4 is excellent, over 8 is bad
40
What position of accuracy is needed for variable rate herbicide?
1 meter
41
What's a good task for Point Guidance?
Locating a drain tile discharge point
42
Recommended accuracy for row crop planting?
10 cm
43
Recommended accuracy for seed bed formation?
5 cm
44
Recommended accuracy for Yield Mapping?
10 meters
45
Recommended accuracy for fertilizer?
30 meters
46
2 types of guidance systems
Light bar and Map Screen
47
2 Modes for GPS Guidance
Error (inches off from line) or Correction (inches to adjust)
48
2 types of steering systems
Universal and Fully Integrated
49
Advantages of GPS Guidance:
```
High accuracy
reduced swath errors
works any time
easy to use
works in any weather
works well with spinner spreaders
```
50
Definition of precision agriculture
a management system that is tech based, site specific, uses data to reach optimum profitability
51
How to get started in precision ag
```
Review existing info
Add more Data
Research tech
Add tech that fits (yield monitor, swath guidance, soil sampling)
Examine Results
Develop a strategy
```
52
FMIS
GIS
Database,
Analytics
Business management
Office system can include book keeping, field management, decision support system
53
Why do we need information on a field?
```
Spatial variability (chg over distance)
Temporal variability (chg over time)
```
54
Ways to acquire data
Real Time - sensors - yield sensor, crop sensor, temp control
Lab Analysis - soil tests. Predictive or Diagnostic
Field Observations - yield history, scout reports
55
Real Time Data
Measurand - physical parameter of interest
Sensor - device that detects change as a signal
Transducer - converts signal to useable form
Processor - analyzes it
Output Display - user interface readout
Direct Sensor - needs physical contact
Remote sensor - no contact, maybe EM
Rate Sensor - tachometer, speed
Proximity Sensor - magnetic displacement
Force/Pressure sensor - strain, load, displacement
Flow Sensor - turbines, ultrasonic, electromagnetic
Temp Sensor - infrared bimetallic, thermocouplers
Chemical Property Sensors - PH, conductivity
Electromagentic - radiometers, measure reflected infrared
56
In-field sensing
direct contact or proximity, but while in the field itself
make sure sensors are calibrated
identify measureable property
57
Remote Sensing
Aerial, Satellite, drone
measures EM energy, UV, infrared, visible
Active (RADAR) or Passive (camera)
Spectral resolution - wavelengths detected
Coverage frequency - how often is data collected/repeated
58
Rules about information
```
Must be managed by type/application
Must be searchable
Must be formatted for analysis
Must be readily available
Must be understandable
```
59
Field Computer
has GNSS receiver, has CAN interface, runs apps or control algorithms
60
Function of cell modems and wifi on the farm
```
Track location
Track service hours
Create auto steer guidelines
geofencing
Transfer sensor data
Send prescription maps
Upload yield data
```
61
GIS
Computer system designed to collect, store and manipulate data
Georeferenced Data
Spatial Data can be vector or raster (tiff, gif, bmp)
62
Raster Data
array of cells
Each cell is georeferenced
each cell has a fixed resolution
each cell is a single attribute
63
Aerial Images
zoom factor is tied to pixel count
| one pixel = 1 meter or 10
64
Coord System
framework used to define position of points
| Lat/Long/evelation
65
datum
a reference from which measurements are made
geomatic datum - uses ellipsoid (horizontal or vertical)
horizontal datum - NAD83, WGS84
vertical datum - used for elevation, tides
66
State Plane
```
Cartesian coords. northing, easting, elevation
N
|
| _ _ _ _ _ _ _ E
0,0
```
67
Different Feet
survey ft - 0.30480061 meter
| international ft 0.3048 meter
68
Geodetic height
height above ellipsoid
69
elevation
height above sea level h = H + N
| ellipsoid height = ortho height + geoid height
70
Georeferencing photos
```
Input control points
choose coord system
minimize residuals (difference between actual control points and coords predicted)
```
71
normalized map
starts with 100, and then shows deviation from that (high/low)
72
FMIS Analysis
Comparison Analysis
Correlation - -1 to 1, statistics
profit/loss, expense/income estimates
73
Files need for shapefile
shp
shx
dbf
projection optional
74
PNT
```
Position, navigation and timing system
'aid in determination of location, provide guidance, and precise coordination of time'
1) provide location
2) available on demand
3) available anywhere
4) must interface w/ equipment
```
75
Types of PNT
Dead Reckoning - orienteering, uses bearings
Laser Systems - transmitters/reflectors. Uses triangulation with 2+ transmitters, need line of sight
GNSS - GPS, GLONASS, Galileo, Beidou
76
GNSS
Space and land based system for location, guidance and timing
GPS: Space - 24 satellites plus backups. In medium earth orbit., orbit earth twice a day
Shifts west a bit every day. 6 orbital planes, broadcast 2 frequencies L1 and L2, plus new L5
Control - monitors satellites, position of each is maintained
User - receiver interprets signal
77
GPS Signal contents
```
Pseudorandom Nosie (uniquely identifies satellite), C/A Code (C for civies, P for military)
NAV data message: ephemeris (broadcast by all satellites, provides precise location of satellite) and almanac (where each satellite should be) inside
```
78
Limits of GPS
Line of sight
low power signals - not go through solid objects
tree cover a problem
79
Pseudorandom Range
Estimate of distance from satellite
80
Carrier phase
time difference between when signal was sent and received
81
trilateration
determine position from known points
4 satellites needed for a unique point
plus reduces clock error
82
autonomous GPS
based on only GPS
Single Point Positioning
horizontal accurate to 8m
vertical accurate to 13m
83
Types of Augmented GNSS
Differential (DGNSS)
Precise Point (PPP)
Real Time Kinematic (RTK)
84
Can improve GPS error by:
Averaging multiple observations
applying differential correction by a reference receiver (known other locations)
applying correction by predictive modeling of error (PPP)
85
DGNSS
references receivers at known locations to transmit a correction signal which is picked up by a differential receiver
removes clock error and orbital error
reduces ionosphere error and troposphere error
1) signal to receiver and fixed reference at same time
2) fixed receiver calculates error in position
3) fixed receiver transmits error out to diff receiver
4) mobile receiver calculates more precise location
Diff signals can come from land or space
Coast Guard or DOT, private stations, commercial (Omnistar, Terrastar)
WAAS (US) - wide area augmentation system
EGNOSE
MSAS (Asia)
86
PPP
correction in real time w/o base stations
uses predicted model of orbit and atmosphere
correction/model from the satellitte
have to wait for it to converge - sometimes 5 minutes
87
RTK
position from carrier phase
number of wavelengths between sat and receiver
accurate to 2 cm horizontal, 3 cm vertical
high speed/low latency
need 5 satellites
uses local base station good for 12 miles
88
RTK base station
fixed or portable
or subscription to a tower cluster
CORS covers whole state, NC realtime network
89
NTRIP
access via cell or dsl or sat. multi-base or single
90
NMEA Sentences
```
GGA - fix data - 4 = RTK
GLL - lat long
RMC
VTG - ground/speed
ZDA - time/date, UTC
plus a checksum
```
91
Baud Rate
needs to be fast enough to transfer data, but too slow garbles it
excess speed uses too much processor
rate = (bytes per sentence) x upload rate (Hertz) X 8 bits/byte
max 82 bytes per sentence
9600, 19200, 38400
92
Pass to PAss accuracy
paralell swatsh, repeatability accuracy within 15 minutes
93
Lightbar setup
Needs clear antenna view
Set swath width
set sensitivity and error vs correction mode
94
universal auto steer
turns the steering wheel via a motor
| can retrofit for any tractor
95
fully integrated steering
interfaces with hydraulics and electrical. Kits are model specific
96
Universal motor install
Install support bracket
install motor
install terrain compensator - needs no vibrations, parallel to rear axle (may or may not be on top of it)
97
wheelbase
center of axle to center of axle
98
antenna height
use manufactorer reference point
99
angle per turn
one full turn of the wheel = number of degrees axle rotates (can self-calculate)
100
override sensitivity
how much you need to touch wheel before auto steer disengages
101
online aggressiveness
how crisp it engages/stays on target
102
maximum angle
must be with X degrees of guidline before auto steer engages
103
accuracy check
```
Program A-B line
stop and flag tires
turn around
drive back to flags
should go between flags
```
104
Advantages of GPS
```
high accuracy
works well w/ spinner spreaders
less chemical use/more efficient
any weather
any time
```
105
Implement setup
```
hitch type - draw bar or 3 pt
width - rows x row spacing
overlap/skip (skip aka alley)
left/right offset from tractor
front/back offset referenced to antenna
```
106
Section Control
on-off control for planters, sprayers, spreaders
switching triggered by field location
each sprayer has a clutch and can disengage/engage on its own. indivduals or groups
Spreaders have no granular control
107
Application Record Map
'as applied' map, good record for fertilizer application
