Hemisphere GPS MBX-4 User Manual Download Page 84

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MBX-4 User Guide

Low SNR

Check integrity of antenna connections

Check MBA-3 antenna ground

Select alternate antenna position

Non-differential GPS output

Verify MBX-4 lock status

Verify matched MBX-4 output and GPS RTCM input baud
rates

Verify GPS receiver RTCM compatibility

Verify GPS receiver DGPS configuration

Verify pin connectivity between MBX-4 and GPS receiver

Verify communication parameter settings (8 data bits - No
parity - 1 stop bit)

Verify communication levels of MBX-4 and GPS receiver are
matched ((RS-232C vs RS-422)

Verify data cable connections

No MBX-4 response to
NMEA commands and
queries

Verify baud rate settings of MBX-4 and terminal device
(MBX-4 default baud rate = 4800 bd)

Verify communication parameter settings (8 data bits - No
parity - 1 stop bit)

Check integrity of data cable connections

Verify pin connectivity between MBX-4 and terminal device

Ensure receiver is in MBX-4 mode

Table 5-1: MBX-4 Troubleshooting

Summary of Contents for MBX-4

Page 1: ...MBX 4 User Guide Part No 875 0188 000 Rev A1 ...

Page 2: ...or computer language in any form or by any means electronic mechanical magnetic optical chemical manual or otherwise without the prior written permission of Hemisphere GPS Trademarks Hemisphere GPS and the Hemisphere GPS logo Satloc and the Satloc logo Mapstar Air Star Outback Guidance and eDrive are trademarks of Hemisphere GPS Inc Other trademarks are the properties of their respective owners No...

Page 3: ......

Page 4: ...f the warranty period Hemisphere GPS does not warrant or guarantee the precision or accuracy of positions obtained when using Products Products are not intended for primary navigation or for use in safety of life applications The potential accuracy of Products as stated in Hemisphere GPS literature and or Product specifications serves to provide only an estimate of achievable accuracy based on Spe...

Page 5: ...ing Warranty Service In order to obtain warranty service the end purchaser must bring the Product to a Hemisphere GPS approved service center along with the end purchaser s proof of purchase For any questions regarding warranty service or to obtain information regarding the location of any of Hemisphere GPS approved service centers contact Hemisphere GPS at the following address Hemisphere GPS 756...

Page 6: ...t Works 4 Real Time DGPS 4 DGPS Format 5 Radiobeacon DGPS Service 5 Radiobeacon Range 5 Radiobeacon Reception 7 Radiobeacon DGPS 7 Radiobeacon Coverage 8 Factors Affecting Positioning Accuracy 10 MBX 4 Beacon Receiver Information 13 MGL 4 Combined GPS Magnetic Field Antenna 14 2 Installation 15 System Parts List 16 ...

Page 7: ... 232 and RS 422 Operation 24 Installing the Antenna 26 Antenna Placement to Optimize Reception 26 MGL 4 Combined GPS Beacon Antenna 27 Routing and Securing the Antenna Cable 27 Magnetic Mount 29 Internal Signal Splitter 30 3 MBX 4 Configuration and Operation 33 Front Display and Keypad 34 Lock Status 35 Factory Default Settings 36 Tune Modes 37 Automatic Beacon Search ABS Mode 37 Manual Mode 38 MB...

Page 8: ...uts 51 MBX 4 Receiver Performance SNR Reading 53 Operation of MBX 4 with Garmin GPS 54 Configuring the Receiver 55 Change Baud Rate 55 Change Frequency and MSK Rate 55 Select a Beacon By Name 55 Set to Automatic Beacon Search Mode 56 Change Display Mode 56 4 NMEA 0183 Interface 59 Interface Protocols 60 Description of NMEA 0183 60 NMEA Message Elements 61 Hemisphere GPS DGPS Command Center 61 ...

Page 9: ...183 Commands 64 Standard Commands 64 Proprietary Commands 66 NMEA 0183 Queries 70 Standard Queries 70 Proprietary Queries 71 5 Troubleshooting 73 Troubleshooting 74 Appendices 77 Appendix A Specifications 78 Appendix B Beacon Information 82 Further Reading 83 ...

Page 10: ...1 Introduction GPS Differential GPS DGPS Format Factors Affecting Positioning Accuracy MBX 4 Beacon Receiver Information MGL 4 Combined GPS Magnetic Field Antenna ...

Page 11: ...ese satellites transmit coded information to GPS users at UHF 1 575 GHz frequencies that allows user equipment to calculate a range to each satellite GPS is essentially a timing system ranges are calculated by timing how long it takes for the GPS signal to reach the user s GPS antenna To calculate a geographic position the GPS receiver uses a complex algorithm incorporating satellite coordinates a...

Page 12: ... to all civilian users In order to maintain a strategic advantage the US DoD has a policy to artificially degrades the performance of the SPS Currently the level of this degradation has been set to zero however in years past this intentional error limited the positioning accuracy of the SPS to 100 meters 95 of the time This policy is called Selective Availability SA Without SA autonomous positioni...

Page 13: ...h satellite is the range error This error is the amount that needs to be removed from each satellite distance measurement in order to correct for errors present in the system Real Time DGPS The base station transmits the range error corrections to remote receivers in real time The remote receiver corrects its satellite range measurements using these differential corrections yielding a much more ac...

Page 14: ...nally controlled by their respective operating authority The United States Coast Guard maintains a broadcast standard that is referenced in the Further Reading section of this manual Radiobeacon Range The broadcasting range of a 300 kHz beacon is dependent upon a number of factors including transmission power free space loss ionospheric state surface conductivity ambient noise and atmospheric loss...

Page 15: ...vels dependent upon conductivity The portion of the beacon signal broadcast skywards is known as the sky wave Depending on its reflectance the sky wave may bounce off the ionosphere and back to Earth causing reception of the ground wave to fade Fading occurs when the ground and sky waves interfere with each other The effect of fading is that reception may fade in and out However this problem usual...

Page 16: ...n DGPS Radiobeacons conforming to the standards of the International Association of Lighthouse Authorities broadcast a limited selection of RTCM SC 104 messages including message types 1 2 3 5 6 7 9 and 16 A DGPS beacon will broadcast either Type 1 or Type 9 messages both of which contain similar information These two messages contain pseudorange corrections and range rate corrections to each GPS ...

Page 17: ...tuned beacon The Type 16 message provides users with a 90 character text string that may contain information regarding the status of the system weather warnings etc Radiobeacon DGPS is often referred to as a local area service as the data broadcast is appropriate for use within the coverage range of the station and is calculated by a single local GPS reference station Radiobeacon Coverage Figure 1...

Page 18: ...MBX 4 User Guide 9 Figure 1 1 World DGPS Radiobeacon Coverage ...

Page 19: ...e GPS receiver being used at both the reference and remote stations The distance between a remote user and the reference station is often considerable when using 300 kHz DGPS radiobeacons Broadcast ranges may be as great as 450 km 280 miles or more depending primarily upon transmission power and surface conductivity Consequently some of the errors associated with GPS at the base station differ som...

Page 20: ...Without the effects of SA the age of the differential corrections is not as significant but care should be taken to ensure that their age is kept below a couple minutes by ensuring consistent beacon receiver lock To account for latency a GPS receiver can calculate approximate corrections until new corrections are available Calculating the differential correction for a new epoch using old correctio...

Page 21: ...s increase the measured range to a satellite as the signal takes a longer route to the GPS antenna Certain precautions will minimize GPS antenna sensitivity to these reflected signals Operating away from large reflective structures such as buildings or using special antennas and GPS equipment can help to reduce the impact of multipath For most consumer level applications a small amount of multipat...

Page 22: ...suring that you are up and running quickly Low power consumption giving extended battery life Automatic and manual tune modes for versatility Full NMEA 0183 command protocol for configuration operation and monitoring of receiver performance Firmware upgrades uploaded through the serial port Various baud rates for compatibility with differential ready GPS products A 2 line by 16 character display a...

Page 23: ...GL 4 Combined GPS Magnetic Field Antenna The MGL 4 combines two individual antennas an H field Loop antenna and an L1 GPS patch antenna Both of these elements are active and draw their power from the MBX 4 beacon receiver ...

Page 24: ...2 Installation System Parts List Receiver Layout and Connections Installing the Receiver Installing the Antenna Internal Signal Splitter ...

Page 25: ...allation System Parts List The following list of standard equipment is included with the beacon receiver system MBX 4 Receiver MGL 4 Antenna Magnetic mount threaded stem facilitates a 5 8 thread Reference Manual ...

Page 26: ...re 1 1 illustrates the required receiver cable connections Warning The MBX 4 receiver provides 10 VDC across the antenna port labeled ANT Connection to incompatible devices may result in damage to equipment No voltage is provided on the GPS port and any voltage applied to this port from an external GPS product is DC blocked for protection of the MBX 4 ...

Page 27: ...18 2 Installation Figure 2 1 Receiver Cable Interface ...

Page 28: ...is available at the back of the receiver to connect and disconnect the power data antenna and ground cables if required Once you have installed the receiver cables will not be bent or pinched as the receiver is tilted up or down You have a clear view and access to the receiver s front panel to monitor the receiver status if you require Environmental Considerations The MBX 4 is designed to operate ...

Page 29: ...2 1 Power Requirements of the MBX 4 To power the receiver 1 Connect the red wire of the supplied power cable to DC positive 2 Connect the black wire of the supplied power cable to DC negative 3 Connect the keyed two conductor socket connector of the power cable to the receiver s power input connector labeled PWR Both receivers possess reverse polarity protection to prevent damage if the power lead...

Page 30: ...e Connecting the Receiver To External Devices Both receivers support RS 232C default and RS 422 interface levels for communication with differentially capable GPS products They feature one external bi directional data port used for transmitting RTCM SC 104 differential correction data to a GPS receiver and for remote control and querying of the beacon receiver using a terminal device This data por...

Page 31: ...ng device transmit line This is required for display of GPS information on the MBX 4 LCD display when in BX E mode and for tuning of the MBX 4 receiver remotely You must connect the signal ground pin 5 of the beacon receiver to the signal ground of the external GPS device Table 2 2 Receiver data pin out RS 232 interface level Pin number Signal Description 2 Transmit RTCM SC 104 status output 3 Rec...

Page 32: ...For successful communications the baud rate of the beacon receiver must be set to match that of the GPS receiver Refer to the Change Baud Rate section on page 51 for instructions set the MBX 4 baud rate using the display and keypad and the MBX 4 Port Rate Command PCSI 6 section on page 63 for information to change the baud rate using proprietary NMEA commands MBX 3S Pin 2 Tx GPS Pin 3 Rx Tx Rx Sig...

Page 33: ...ons include proper grounding of personnel tools and the surface upon which the receiver rests You will require a Philip s screwdriver to open the front and back panels of the MBX 4 Once you have removed the front panel screws for the MBX 4 carefully remove the front plate and disconnect the ribbon cables of the display and keypad taking note of connector orientation when secured Do not pull on the...

Page 34: ...cuit board for identification Once you have set the slide switch to the desired position slide the receiver board back into the enclosure Reconnect the front panel display and keypad ribbon cables When replacing the front and back plate screws ensure that no cables or components catch between the panels and the housing Warning The MBX 4 is an electrostatic sensitive device Observe proper precautio...

Page 35: ...etter your receiver is receiving the signal The optimum antenna location will be a position where your average SNR is highest You should turn on all accessories that you intend to use during normal operation when locating the best position for the antenna The MBX 4 receiver displays the SNR within the Beacon Status menu You may alternatively issue a NMEA query to the receiver through the serial po...

Page 36: ...n cable such as RG 58U up to a maximum of 492 feet 150 meters in length for proper operation in the case of the combined MGL 4 cable losses at the higher GPS frequency 1 575 GHz restrict the cable length to approximately 32 8 feet 10 meters for RG 58U cable depending on GPS receiver requirements For more information on cable length please contact your Hemisphere GPS dealer or Hemisphere GPS techni...

Page 37: ...nsion on the cable Remove unwanted slack from the antenna extension cable at the receiver end Secure along the cable route using plastic tie wraps Warning The MBX 4 receiver provides 10 VDC across the antenna port Connection to incompatible devices may result in damage to equipment No voltage is provided on the GPS port and any voltage applied to this port from an external GPS product is DC blocke...

Page 38: ...er zinc plated steel disc and a double sided adhesive foam pad are included with the magnetic mount to attach the magnetic mount to non ferrous surfaces such as fiberglass rooftops For such an installation remove the protective backing from both sides of the adhesive foam pad and affix the foam pad to the non ferrous surface Place the disc on top of the foam pad You can then place the magnetic mou...

Page 39: ...ed to the internal beacon receiver while the GPS signal is re directed out of the receiver through the TNC S coaxial connector labeled GPS see Figure 2 6 This feature eliminates the need for a separate GPS antenna or an external splitter box reducing the amount of cable required for an installation No voltage is provided through this port and any voltage applied to this port from an external GPS p...

Page 40: ...MBX 4 User Guide 31 Figure 2 5 MBX 4 Internal Signal Splitter Interface ...

Page 41: ...32 2 Installation ...

Page 42: ...guration and Operation Front Display and Keypad Factory Default Settings Tune Modes Display Modes MBX 4 Menu Systems MBX 4 Receiver Performance SNR Reading Operation of MBX 4 with Garmin GPS Configuring the Receiver ...

Page 43: ...itive MBX 4 menu system configuring operating parameters and viewing status information Figure 3 1 shows the display and keypad of the MBX 4 The top line of the display is the active Focus Line for keypad operations Figure 3 1 MBX 4 Display and Keypad Note The top line of the MBX 4 display is the Focus Line denoted by the left and right arrows on either side of the display The field of interest mu...

Page 44: ... hand corner of the display The lock symbol illustrated in Figure 3 2 remains in the closed position when the MBX 4 is locked to an RTCM signal and open when no broadcast is available for the specified frequency and or MSK bit rate Figure 3 2 MBX 4 Beacon Lock Indicator No Lock Lock ...

Page 45: ...e valid upon initial power up The MBX 4 maintains any changes made to its operation or port settings for subsequent power up Note The changes you make to the MBX 4 configuration are saved in memory for subsequent power up Table 3 1 Default MBX 4 Operating Settings Tune Mode Display Mode Automatic MBX 4 Table 3 2 Default MBX 4 Port Settings Baud Rate Data Bits Parity Stop Bit Interface Level P1 Mai...

Page 46: ...de is ideal for navigation applications over considerable areas eliminating the need for operator intervention when travelling from one beacon coverage zone to another Global Search When powered for the first time in ABS mode the MBX 4 initiates a Global Search examining each available DGPS beacon frequency and recording Signal Strength SS measurements in units of dBmV m to the Global Search Table...

Page 47: ...y so that it is available upon subsequent power up You may force a new Global Search at any time using the proprietary NMEA 0183 command defined in Chapter 5 Manual Mode In Manual tune mode you may select a specific frequency and bit rate for the receiver to tune to or simply specify the frequency allowing the MBX 4 to identify the correct MSK bit rate on its own This mode of operation is most use...

Page 48: ...ernal GPS input mode standard NMEA 0183 GPS messages GPGGA GPVTG GPZDA and GPGSV are input from an external GPS receiver and the position navigation and satellite information contained within these messages is displayed by the MBX 4 The MBX 4 continues to output RTCM data to the external GPS device while in this mode This feature can be very useful when working with a GPS receiver that does not pr...

Page 49: ...PS lock Figure 3 3 BX E Position Fix Indicator In the first state the two parallel vertical lines indicate that no position fix is available The second state denoted by the hollow circle between the two parallel vertical lines states that the receiver is tracking four satellites or more and is computing a position This indicator is a symbol representing a GPS satellite The third state denoted by t...

Page 50: ...tions Auto Bx Search Tune 305 0 200 Select Beacon Subscription Version Display Stn 305 0 B200 SS 000 SNR 000 PRF 100 Q25 Unselected Bx ID 00000 H 0 Baud Rt 4800 XBX3 Mode Hgt Unit Meters Back Continent Country Beacon Name Back Back Lat Lon Hgt Hdg UTC Age Back Back Back Back HDOP Ch12 SV00 El00 Az 000 SNR 00 BX E Mode BX Mode Enter Key Down Arrow Up Arrow Short Cut User Entry Legend SV Count Vel U...

Page 51: ... the Beacon Status branch of the menu tree When operating in BX mode the BX will proceed directly to the Position Status branch of the menu tree Beacon Status The Beacon Status section of the menu tree provides access to information related to the status of the receiver s primary channel Stn Frequency in kHz to which the MBX 4 is tuned B MSK bit rate in bits per second bps at which the MBX 4 is de...

Page 52: ...eceiver is tuned This field is only updated if a specific beacon is selected from the receiver s Global Beacon Table ID Reference station identifier as contained within the RTCM broadcast messages H Health of the transmitting beacon Table 3 3 defines the various health values Table 3 3 Beacon Health Status Values Health Code Indication 0 5 Reference Station Transmission Broadcast Monitored 6 Refer...

Page 53: ...ormation and sub menus The Options sub menu provides access to the following configuration parameters 1 O p t i o n s Focus Line 2 A u t o B X S e a r c h 3 T u n e 3 2 5 0 2 0 0 4 S e l e c t B e a c o n 5 S u b s c r i p t i o n 6 V e r s i o n D i s p l a y 7 B a c k 1 B a u d R t 4 8 0 0 Focus Line 2 X B X 3 M o d e B X 3 L L U n i t D M M 4 H g t U n i t M e t e r s 5 V e l U n i t K P H 6 U ...

Page 54: ... GPS position navigation and satellite data as input from an external GPS device GGA VTG ZDA GSV NMEA message input required GBXNot applicable only used with GBX Series combination Beacon GPS receivers Do not configure the MBX 4 for this mode of operation GBX ENot applicable only used with GBX Series combination Beacon GPS receivers Do not configure the MBX 4 for this mode of operation GLXMode of ...

Page 55: ...sing with this line in focus allows you set the units of the Vel parameter displayed in the Position Status section of the menu in BX E mode Use the and keys to select the desired units kilometers hour miles hour or knots and press again to implement the change UTC Offset 12 to 12 hours Pressing with this line in focus allows you set the local time offset from UTC allowing the display of local tim...

Page 56: ...in of the correct MSK rate When the correct frequency and bit rate is displayed press to proceed to the Beacon Status menu Select Beacon This feature allows you to select a particular beacon for a geographical region Geographic regions are resolved into continent and country Upon selecting a beacon the MBX 4 will automatically return to the Beacon Status menu updating the Stn B and beacon name fie...

Page 57: ...the current latitude in degrees minutes decimal minutes DM M as input from an external GPS receiver This information is parsed from the NMEA GPGGA message string Lon Displays the current longitude in degrees minutes decimal minutes DM M as input from an external GPS receiver This information is parsed from the NMEA GPGGA message string 1 L a t 5 1 4 6 2 3 4 N Focus Line 2 L o n 1 1 4 0 3 1 4 3 W 3...

Page 58: ...ormation is parsed from the NMEA GPVTG message string UTC Displays the current UTC Time with local offset as input from an external GPS receiver See Chapter 4 This information is parsed from the NMEA GPZDA message string Age Displays the current DGPS age of correction in seconds as input from an external GPS receiver This information is parsed from the NMEA GPGGA message string SV Count Displays t...

Page 59: ...s numbered Ch01 through Ch12 Ch01 Displays the external GPS receiver channel 01 12 for which the satellite information provided is valid This information is parsed from the NMEA GPGSV or PASHS SAT message strings SV12 Displays the GPS satellite SV number tracked by channel XX of the external GPS receiver This information is parsed from the NMEA GPGSV or PASHS SAT message strings El Displays the el...

Page 60: ...t more efficiently A shortcut allows you to move from one menu directly to separate menu without having to choose the Back menu item When Stn B of the Beacon Status menu is in focus you may press to proceed directly to the Tune command line of the Setup menu You may then press again to change the frequency and bit rate to which the receiver is tuned using the and keys When the correct frequency an...

Page 61: ...rn to the Beacon Status menu In BX E mode when Lat of the Position Status is in focus you may press to proceed directly to the Beacon Status menu allowing you to monitor beacon receiver performance quickly In BX E mode when SV Count is in focus you may press to proceed directly to the Satellites status menu ...

Page 62: ...nterfacing to a PC computer running a terminal program using the GPCRQ NMEA sentence discussed in Chapter 4 NMEA 0183 Interface Table 3 4 describes the general quality of reception with respect to the SNR reading of the MBX 4 Table 3 4 Receiver Performance SNR Reading SNR Reception Description Data Throughput 25 Excellent 100 data throughput 20 to 25 Very Good 100 data throughput 15 to 20 Good Goo...

Page 63: ...rmation relating to performance than that of the Garmin receiver including signal strength SS message throughput MTP station ID and station health However the Garmin may display distance to the beacon dependent upon the transmission of beacon station coordinates within the RTCM Type 3 message When interfacing a Garmin GPS receiver with the MBX 4 set the input output protocols to RTCM NMEA and chan...

Page 64: ...ting If incorrect press Scroll with the or keys to the correct baud rate 2400 4800 or 9600 and press Change Frequency and MSK Rate To modify the frequency and MSK rate to which the receiver is manually tuned Refer to Figure 3 4 Navigate to Tune in the Setup menu and press Scroll with the or keys until the desired Frequency and MSK Rate are displayed and press 283 5 100 to Auto Auto Select a Beacon...

Page 65: ...on Search Mode To set the receiver to ABS mode Refer to Figure 3 4 Navigate to Auto Bx Search in the Setup menu and press or Navigate to Tune in the Setup menu and press Scroll with the or keys until Auto Auto is displayed and press The previous method erases any previous search information while the later method does not Change Display Mode To change display mode Refer to Figure 3 4 Navigate to O...

Page 66: ...MBX 4 User Guide 57 Scroll with the or keys to the correct mode BX or BX E and press ...

Page 67: ...58 3 MBX 4 Configuration and Operation ...

Page 68: ...4 NMEA 0183 Interface Interface Protocols NMEA 0183 Commands NMEA 0183 Queries ...

Page 69: ...ble of processing a subset of standard NMEA 0183 messages along with a selection of proprietary NMEA 0183 formatted messages NMEA 0183 is a communication standard established by the marine industry It has found use in a variety of marine electronics devices including ship borne radar systems Loran C navigation devices and more recently GPS The National Marine Electronic Association has developed a...

Page 70: ... it represents both a carriage return CR and line feed LF If a NMEA command is not working this terminal facility option may not be set correctly Please contact your dealer or Hemisphere GPS Technical Service for more information Hemisphere GPS DGPS Command Center If you are using Hemisphere GPS DGPS Command Center program the terminal window allows you to issue NMEA commands or queries to the MBX...

Page 71: ...I 4 Proprietary Erases the Global Search table forcing a new search PCSI 5 Proprietary Reserved Factory use only PCSI 6 Proprietary Sets the internal and external MBX 4 baud rates PCSI 7 Proprietary Sets the display mode of the MBX 4 receiver PSLIB Proprietary Sets the frequency and MSK bit rate of the MBX 4 Queries GPCRQ Operation Query Queries the receiver for operation parameters GPCRQ Performa...

Page 72: ...or query messages The intent of this message is to confirm that communication exists between the beacon receiver and the terminal device Descriptions of the response messages specific to each command and query are provided below the related command in the following sections N A indicates that the receiver does not provide a response for that particular message ...

Page 73: ... CR LF In this message fff f is the frequency in kHz and M designates manual frequency selection The ddd field represents the desired MSK bit rate in bits per second 100 200 bps or non standard and the second M designates manual MSK rate The n parameter is the period of the performance status message output by the receiver 0 to 100 seconds When power is cycled the status output interval resets to ...

Page 74: ...sets to zero Again the status output is the CRMSS message response discussed in Chapter 4 Automatic Beacon Search Command GPMSK This command initiates the MBX 4 automatic mode of operation in which the receiver operates without operator intervention selecting the most appropriate beacon station This command has the following format GPMSK A A n CR LF MBX 4 Response PCSI ACK GPMSK A A 0 CR LF In thi...

Page 75: ...phere GPS proprietary NMEA 0183 formatted commands and their responses Wipe Search Command PCSI 4 The Wipe Search command instructs the MBX 4 to erase all parameters within the beacon almanac and to initiate a new Global Search to identify the beacon signals available for a particular area The command has the following form PCSI 4 CR LF MBX 4 Response PCSI ACK 4 CR LF When this command has been is...

Page 76: ...P4 r4 In this message rx designates the MBX 4 communications port baud rate for the one external and three internal MBX 4 host communication ports P1 P2 P3 and P4 Baud rates r1 r2 r3 and r4 are selected from Table 4 3 Warning Only P1 is applicable to regular MBX 4 operations Leave all others P2 P3 and P4 at their factory pre configured values as defined in Table 4 4 Table 4 3 MBX 4 Baud Rates rx x...

Page 77: ...IB A majority of Garmin hand held and fixed mount GPS receivers output this non standard command from the BEACON RCVR feature of the INTERFACE menu It instructs both the connected beacon receiver to tune to the specified frequency and MSK Rate The command has the following form PSLIB fff f ddd CR LF MBX 4 Response N A Table 4 5 MBX 4 Display Modes m Mode 1 BX 2 GBX 4 GBX E 8 BX E Note Only BX and ...

Page 78: ...MBX 4 User Guide 69 In this message fff f is the frequency in kHz 283 5 325 kHz 0 Auto The ddd field represents the desired MSK bit rate in bits per second 100 200 bps 0 Auto ...

Page 79: ...rmat GPCRQ MSK CR LF MBX 4 Response CRMSK fff f X ddd Y n CS When queried for their operational status both receivers will return this NMEA response where fff f is the current frequency in kHz X is the tune mode A automatic and M manual ddd is the MSK bit rate Y is the MSK mode A automatic and M manual and n is the output period of the CRMSS performance status message The CS field is the checksum ...

Page 80: ...ubsections describe the selection of valid Hemisphere GPS proprietary NMEA 0183 queries and their responses Receiver Help Query PCSI 0 This command queries the MBX 4 receiver for a list of valid proprietary PCSI commands PCSI 0 CR LF MBX 4 Response PCSI 0 PCSI ACK 0 PCSI P012 0 010 PCSI 0 HELP Msg PCSI 1 Reserved PCSI 2 Reserved PCSI 3 Reserved PCSI 4 Wipe Search PCSI 5 GPS SBX3a Port Rate P4 PCSI...

Page 81: ...72 4 NMEA 0183 Interface ...

Page 82: ...5 Troubleshooting ...

Page 83: ... imposed by power source maximum 0 5 A No data from MBX 4 Check receiver power status display illuminated Verify that MBX 4 is locked to a valid beacon Lock symbol engaged Check integrity of power antenna and data cable connections Receiver in MBX 4 or MBX E mode only Random data from MBX 4 Check transmitting beacon status Verify baud rate settings of MBX 4 and terminal device MBX 4 default baud r...

Page 84: ...eceiver Verify communication parameter settings 8 data bits No parity 1 stop bit Verify communication levels of MBX 4 and GPS receiver are matched RS 232C vs RS 422 Verify data cable connections No MBX 4 response to NMEA commands and queries Verify baud rate settings of MBX 4 and terminal device MBX 4 default baud rate 4800 bd Verify communication parameter settings 8 data bits No parity 1 stop bi...

Page 85: ...76 5 Troubleshooting ...

Page 86: ...Appendices Appendix A Specifications Appendix B Beacon Information Further Reading ...

Page 87: ...pecifications Operational Specifications Item Specification Frequency Range 283 5 325 kHz Channels 2 Input Sensitivity 2 5 mV m for 10 dB SNR 100 bps MSK Rate Acquisition Time 1 Second Typical MSK Bit Rate 100 200 or Automatic Frequency Selection Manual or Automatic Frequency Offset 5 Hz Dynamic Range 100 dB Adjacent Channel Rejection 60 dB f0 500 Hz Decoding RTCM 6 8 Demodulation MSK Serial Inter...

Page 88: ...tor Circular 2 pin Locking Plug Mechanical Characteristics Item Specification Display 2 line 16 character LCD Keypad 3 switch membrane Enclosure Extruded Aluminum with Aluminum Front and Back Plates Length 150 mm 5 9 Width 125 mm 4 9 Height 51 mm 2 0 Weight 0 64 kg 1 4 lb Antenna Connector BNC Socket Optional GPS Signal Output Connector TNC Socket Environmental Specifications Item Specification St...

Page 89: ...ow Noise Amplifier Frequency Range GPS 1 575 GHz L1 LNA Gain GPS Various available Power Specifications Item Specification Input Voltage 4 9 13 VDC supplied by receiver Input Current 50 60 mA Mechanical Characteristics Item Specification Enclosure PVC Plastic Mounting Thread 1 14 UNS 2B Length 128 mm 5 06 Width 128 mm 5 06 Height 84 mm 3 33 Weight 450 g 1 0 lb Antenna Connector TNC S Antenna Exten...

Page 90: ...rage Temperature 40 C to 80 C Operating Temperature 30 C to 70 C Humidity 100 Condensing Item Specification BCN Port GPS Frequency Insertion Loss 35 dB nominal 25 dB min BCN Port Beacon Insertion Loss 0 2 dB nominal 0 4 dB max GPS Port GPS Frequency 3 5 dB nominal 5 dB max GPS Port Beacon Frequency 70 dB typical 58 dB min ...

Page 91: ...e that is available on the Internet from the Hemisphere GPS home page www hemispheregps com This listing contains the following information regarding currently operating beacons and potential new sites Station name Frequency MSK rate Location Transmitting ID Reference station ID Field Strength Operating notes ...

Page 92: ...o Technical Commission for Maritime Services RTCM Recommended Standards for Differential NAVSTAR GPS Service Version 2 2 Developed by Special Committee No 104 RTCM 1998 1800 Diagonal Rd Suite 600 Alexandria VA 22314 2840 USA Tel 1 703 684 4481 Fax 1 703 836 4429 US Department of Transportation United States Coast Guard Broadcast Standard for the USCG DGPS Navigation Service COMDTINST M16577 1 Apri...

Page 93: ...84 Appendices ...

Page 94: ...www hemispheregps com e mail info hemispheregps com ...

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