Globalsat EM-408 User Manual

環天衛星科技股份有限公司

PRODUCT USER MANUAL

GPS ENGINE BOARD

EM-408

GlobalSat Technology Corporation
台北縣中和市建一路 186 號 16 樓(遠東世紀廣場)
16F ,No.186,Chien 1 Road, 235Chung Ho City,Taipei Hsien, Taiwan ,R.O.C.

Tel: [phone](Rep.) Fax: [phone]
Web: www.globalsat.com.tw E-mail: [e-mail]
Features:

SiRF starⅢ high performance GPS Chip Set
Very high sensitivity (Tracking Sensitivity: -159 dBm)
Extremely fast TTFF (Time To First Fix) at low signal level
Compact size (36.4mm * 35.4 mm * 8.3mm) suitable for space-sensitive application
Support NMEA 0183 and SiRF binary protocol

Specification:

General

Chipset SiRF StarⅢ
Frequency L1, 1575.42 MHz
C/A code 1.023 MHz chip rate
Channels 20 channel all-in-view tracking
Sensitivity -159 dBm

Accuracy

Position 10 meters, 2D RMS
5 meters, 2D RMS, WAAS enabled
Velocity 0.1 m/s
Time 1us synchronized to GPS time

Datum

Default WGS-84

Acquisition Time

Reacquisition 0.1 sec., average
Hot start 1 sec., average
Warm start 38 sec., average
Cold start 42 sec., average

Dynamic Conditions

Altitude 18,000 meters (60,000 feet) max
Velocity 515 meters /second (1000 knots) max
Acceleration Less than 4g

Jerk 20m/sec **3

Power

Main power input 3.3V DC input
Power consumption 75mA (Continuous mode)

Interface

Dimension 36.4mm * 35.4mm * 8.3mm
Baud rate 4,800 to 57,600 bps adjustable
Electrical level TTL level, Output voltage level: 0V ~ 2.85V
Output message SiRF binary or

NMEA 0183 GGA, GSA, GS V, RMC, VTG, GLL

Environmental

Operating Temp -40℃ to +85℃

Dimensions

Pin Assignment

Pin description
* VIN (DC power input):

This is the main DC supply for a 3.3V DC input power module board.

* GPS-TX:

This is the main transmits channel for outputting navigation and measurement
data to user’s navigation software or user written software.
Output TTL level, 0V ~ 2.85V

* GPS-RX:

This is the main receive channel for receiving software commands to the engine
board from SiRFdemo software or from user written software.

* GND:

GND provides the ground for the engine board. Connect all grounds.

* Enable/Disable:

On/Off

SOFTWARE COMMAND

$

p

r

N

N N

m

t

N

p

d

d

d

d

NMEA Output Command

GGA-Global Positioning System Fixed Data

Table B-2 contains the values for the following example:

$GPGGA,161229.487,3723.2475,N,12158.3416,W,1,07,1.0,9.0,M,,,,0000*18

Table B-2 GGA Data Format

Message ID

GPGGA GGA

rotocol heade
UTC Time 161229.487 hhmmss.sss
Latitude 3723.2475 ddmm.mmmm

/S Indicator

=north or S=south
Longitude 12158.3416 dddmm.mmm
E/W Indicator W E=east or W=wes
Position Fix Indicator 1 See Table B-3
Satellites Used 07 Range 0 to 12
HDOP 1.0 Horizontal Dilution of Precision
MSL Altitude

1

9.0 meters
Units M meters
Geoid Separation

1

meters
Units M meters
Age of Diff. Corr. second

ull fields when DGPS is not used
Diff. Ref. Station ID 0000
Checksum *18
<CR><LF> End of message termination

SiRF Technology Inc. does not support geoid corrections. Values are WGS84 ellipsoid heights.

Table B-3 Position Fix Indicator

Value Descri
0 Fix not available or invali
1 GPS SPS Mode, fix vali
2 Differential GPS, SPS Mode , fix vali
3 GPS PPS Mode, fix vali

tion

p

$

p

r

N

N

m

t

GLL-Geographic Position-Latitude/Longitude

Table B-4 contains the values for the following example:

$GPGLL,3723.2475,N,12158.3416,W,161229.487,A*2C

Table B-4 GLL Data Format
Name Exam

Message ID

GPGLL GLL

le Units Description

rotocol heade

Latitude 3723.2475 ddmm.mmmm

/S Indicator n

=north or S=south
Longitude 12158.3416 dddmm.mmm
E/W Indicator W E=east or W=wes
UTC Position 161229.487 hhmmss.sss
Status A A=data valid or V=data not valid
Checksum *2C
<CR><LF> End of message termination

GSA-GNSS DOP and Active Satellites

$GPGSA,A,3,07,02,26,27,09,04,15,,,,,,1.8,1.0,1.5*33

Table B-5 GSA Data Format

Table B-5 contains the values for the following example:

Name Example Units Description

Message ID $GPGSA GSA protocol header
Mode1 A See Table B-6
Mode2 3 See Table B-7
Satellite Used
Satellite Used
…..
Satellite Used

1
1

1

07 Sv on Channel 1
02 Sv on Channel 2

Sv on Channel 12
PDOP 1.8 Position dilution of Precision
HDOP 1.0 Horizontal dilution of Precision
VDOP 1.5 Vertical dilution of Precision
Checksum *33
<CR><LF> End of message termination

1. Satellite used in solution.

Table B-6 Mode1

Value Description

M Manual-forced to operate in 2D or 3D mode
A 2Dautomatic-allowed to automatically switch 2D/3D

Table B-7 Mode 2

Value Description

1 Fix Not Available
2 2D
3 3D

GSV-GNSS Satellites in View

$

r

N

r

)

)

)

)

$

N

N N

m

t

yy

t

Table B-8 contains the values for the following example:

$GPGSV,2,1,07,07,79,048,42,02,51,062,43,26,36,256,42,27,27,138,42*71
$GPGSV,2,2,07,09,23,313,42,04,19,159,41,15,12,041,42*41
Table B-8 GSV Data Format

Message ID

GPGSV GSV protocol heade

umber of Messages12 Range 1 to 3

Message Numbe

1

1 Range 1 to 3
Satellites in View 07
Satellite ID 07 Channel 1(Range 1 to 32
Elevation 79 degrees Channel 1(Maximum90
Azimuth 048 degrees Channel 1(True, Range 0 to 359)
SNR(C/No) 42 dBHz Range 0 to 99,null when not tracking
……. …….
Satellite ID 27 Channel 4 (Range 1 to 32
Elevation 27 Degrees Channel 4(Maximum90
Azimuth 138 Degrees Channel 4(True, Range 0 to 359)
SNR(C/No) 42 dBHz Range 0 to 99,null when not tracking
Checksum *71
<CR><LF> End of message termination

Depending on the number of satellites tracked multiple messages of GSV data may be required.

RMC-Recommended Minimum Specific GNSS Data

Table B-10 contains the values for the following example:
$GPRMC,161229.487,A,3723.2475,N,12158.3416,W,0.13,309.62,120598,,*10
Table B-10 RMC Data Format

Message ID

GPRMC RMC protocol header
UTC Time 161229.487 hhmmss.sss
Status A A=data valid or V=data not valid
Latitude 3723.2475 ddmm.mmmm

/S Indicator

=north or S=south
Longitude 12158.3416 dddmm.mmm
E/W Indicator W E=east or W=wes
Speed Over Ground 0.13 knots
Course Over Ground 309.62 degrees True
Date 120598 ddmm
Magnetic Variation

2

degrees E=east or W=wes
Checksum *10
<CR><LF> End of message termination
SiRF Technology Inc. does not support magnetic declination. All “course over ground” data are

geodetic WGS48 directions.

$

g

g

N

r

p

VTG-Course Over Ground and Ground Speed

$GPVTG,309.62,T,,M,0.13,N,0.2,K*6E

Message ID
Course 309.62 degrees Measured headin
Reference T True
Course degrees Measured headin
Reference M Magnetic
Speed 0.13 knots Measured horizontal speed
Units
Speed 0.2 Km/h
Units K Kilometers
Checksum *6E
<CR><LF> End of message termination

GPVTG VTG protocol header

Knots

Measured horizontal speed

er hour

2.2 NMEA Input Command

A)

. Set Serial Port ID:100 Set PORTA parameters and protocol

This command message is used to set the protocol(SiRF Binary, NMEA, or
USER1) and/or the communication parameters(baud, data bits, stop bits, parity).
Generally,this command would be used to switch the module back to SiRF Binary
protocol mode where a more extensive command message set is available. For
example,to change navigation parameters. When a valid message is received,the
parameters will be stored in battery backed SRAM and then the receiver will restart
using the saved parameters.

Format:

$PSRF100,<protocol>,<baud>,<DataBits>,<StopBits>,<Parity>*CKSUM
<CR><LF>

<protocol> 0=SiRF Binary, 1=NMEA, 4=USER1
<baud> 1200, 2400, 4800, 9600, 19200, 38400
<DataBits> 8,7. Note that SiRF protocol is only valid f8

Data bits
<StopBits> 0,1
<Parity> 0=None, 1=Odd, 2=Even

Example 1: Switch to SiRF Binary protocol at 9600,8,N,1

$PSRF100,0,9600,8,1,0*0C<CR><LF>

Example 2: Switch to User1 protocol at 38400,8,N,1

$PSRF100,4,38400,8,1,0*38<CR><LF>

**Checksum Field: The absolute value calculated by exclusive-OR the

8 data bits of each character in the Sentence,between, but
excluding “$” and “*”. The hexadecimal value of the most
significant and least significant 4 bits of the result are convertted
to two ASCII characters (0-9,A-F) for transmission. The most

significant character is transmitted first.

**<CR><LF> : Hex 0D 0A

B). Navigation lnitialization ID：101 Parameters required for
start

This command is used to initialize the module for a warm start, by providing current
position （in X, Y, Z coordinates）,clock offset, and time. This enables the receiver

to search for the correct satellite signals at the correct signal parameters. Correct
initialization parameters will enable the receiver to acquire signals more quickly, and
thus, produce a faster navigational solution.

When a valid Navigation Initialization command is received, the receiver will restart
using the input parameters as a basis for satellite selection and acquisition.

Format：

$PSRF101,<X>,<Y>,<Z>,<ClkOffset>,<TimeOfWeek>,<WeekNo>,<chnlCount>,<R
esetCfg>
*CKSUM<CR><LF>

<X> X coordinate position

INT32

<Y> Y coordinate position

INT32

<Z> Z coordinate position

INT32

<ClkOffset> Clock offset of the receiver in Hz, Use 0 for

last saved value if available. If this is
unavailable, a default value of 75000 for
GSP1, 95000 for GSP 1/LX will be used.

INT32

<TimeOf Week> GPS Time Of Week

UINT32

<WeekNo> GPS Week Number
UINT16
（ Week No and Time Of Week calculation

from UTC time）

<chnlCount> Number of channels to use.1-12. If your

CPU throughput is not high enough, you

could decrease needed throughput by
reducing the number of active channels

UBYTE

<ResetCfg> bit mask

0×01=Data Valid warm/hotstarts=1
0×02=clear ephemeris warm start=1
0×04=clear memory. Cold start=1
UBYTE

Example: Start using known position and time.
＄PSRF101,-2686700,-4304200,3851624,96000,497260,921,12,3*7F

C). Set DGPS Port ID:102 Set PORT B parameters for DGPS input

This command is used to control Serial Port B that is an input only serial port
used to receive
RTCM differential corrections.
Differential receivers may output corrections using different
communication parameters.
The default communication parameters for PORT B are 9600
Baud, 8data bits, 0 stop bits, and no parity.
If a DGPS receiver is used which has different communication parameters, use
this command to allow the receiver to correctly decode the data. When a valid
message is received, the parameters will be stored in battery backed SRAM and
then the receiver will restart using the saved parameters.
Format:
＄PSRF102,<Baud>,<DataBits>,<StopBits>,<Parity>*CKSUM<CR><LF>

<baud> 1200,2400,4800,9600,19200,38400
<DataBits> 8
<StopBits> 0,1
<Parity> 0=None,Odd=1,Even=2

Example: Set DGPS Port to be 9600,8,N,1

＄PSRF102,9600,8,1.0*12

D). Query/Rate Control ID:103 Query standard NMEA message and/or set
output rate

This command is used to control the output of standard NMEA message GGA,

GLL, GSA, GSV

RMC, VTG. Using this command message, standard NMEA message may be

polled once, or setup for periodic output. Checksums may also be enabled
or disabled depending on the needs of the receiving program. NMEA
message settings are saved in battery backed memory for each entry when the
message is accepted.

Format:
＄PSRF103,<msg>,<mode>,<rate>,<cksumEnable>*CKSUM<CR><LF>

<msg>
0=GGA,1=GLL,2=GSA,3=GSV,4=RMC,5=VTG
<mode> 0=SetRate,1=Query
<rate> Output every <rate>seconds, off=0,max=255
<cksumEnable> 0=disable Checksum,1=Enable checksum

for specified message

Example 1: Query the GGA message with checksum enabled

＄PSRF103,00,01,00,01*25

Example 2: Enable VTG message for a 1Hz constant output with checksum

enabled

＄PSRF103,05,00,01,01*20

Example 3: Disable VTG message

＄PSRF103,05,00,00,01*21

E). LLA Navigation lnitialization ID:104 Parameters required to start
using Lat/Lon/Alt

This command is used to initialize the module for a warm start, by providing
current position (in Latitude, Longitude, Altitude coordinates), clock offset, and
time. This enables the receiver to search for the correct satellite signals at
the correct signal parameters. Correct initialization parameters will enable
the receiver to acquire signals more quickly, and thus, will produce a faster
navigational soution.
When a valid LLANavigationInitialization command is received,the receiver will
restart using the input parameters as a basis for satellite selection and acquisition.

Format:

＄PSRF104,<Lat>,<Lon>,<Alt>,<ClkOffset>,<TimeOfWeek>,<WeekNo>,
<ChannelCount>, <ResetCfg>*CKSUM<CR><LF>

<Lat> Latitude position, assumed positive north of equator and

negative south of equator float, possibly signed

<Lon> Longitude position, it is assumed positive east of Greenwich

and negative west of Greenwich

Float, possibly signed

<Alt> Altitude position

float, possibly signed

<ClkOffset> Clock Offset of the receiver in Hz, use 0 for last saved value if

available. If this is unavailable, a default value of 75000 for

GSP1, 95000 for GSP1/LX will be used.
INT32
<TimeOfWeek> GPS Time Of Week
UINT32
<WeekNo> GPS Week Number
UINT16
<ChannelCount> Number of channels to use. 1-12

UBYTE

<ResetCfg> bit mask 0×01=Data Valid warm/hot starts=1
0×02=clear ephemeris warm start=1
0×04=clear memory. Cold start=1

UBYTE
Example: Start using known position and time.
＄PSRF104,37.3875111,-121.97232,0,96000,237759,922,12,3*37

F). Development Data On/Off ID:105 Switch Development Data Messages
On/Off

Use this command to enable development debug information if you are having
trouble getting commands accepted. Invalid commands will generate debug
information that should enable the user to determine the source of the
command rejection. Common reasons for input command rejection are invalid
checksum or parameter out of specified range. This setting is not preserved
across a module reset.

Format: ＄PSRF105,<debug>*CKSUM<CR><LF>

<debug> 0=Off,1=On

Example: Debug On ＄PSRF105,1*3E
Example: Debug Off ＄PSRF105,0*3F

G). Select Datum ID:106 Selection of datum to be used for coordinate
Transformations

GPS receivers perform initial position and velocity calculations using an earth-centered
earth-fixed (ECEF) coordinate system. Results may be converted to an earth model (geoid)
defined by the selected datum. The default datum is WGS 84 (World Geodetic System 1984)
which provides a worldwide common grid system that may be translated into local coordinate
systems or map datums. (Local map datums are a best fit to the local shape of the earth and not
valid worldwide.)

Examples:
Datum select TOKYO_MEAN
$PSRF106,178*32