BT-338 Bluetooth GPS FAQ


1.) Q: What is the difference between a BT-338 version 1.0 (v1) and version 2.0 (v2)?   
1.) A: The BT-338 version 2.0 has a revised circuit board that changes function of the auto shut-off, battery extending feature. v1 will turn itself off after 10 minutes of no active Bluetooth connection present, regardless if the GPS is operating from its internal Li-ion battery, or connected to an external power source.  
v2 will still turn itself off after 10 minutes when running from its internal Li-ion battery, but will remain on indefinitely as long as it is connected to an external power source (i.e. car charger or AC charger). Note, this is a hardware modification incorporated. Receivers exhibiting v1 behavior cannot be upgraded to v2 without physical modifications made.

2.) Q: How can I tell which version v1 or V2) of the BT-338 I have?     
2.) A: Any BT-338 with serial numbers between 55301 ~ 63000 and those starting from 67001 and higher are all v2. You can also check by turning on the BT-338 and connecting it to your AC or DC charger, then let it stand for 15 minutes. If the GPS has turned off, you have a version 1.0 device.  (NOTE: BT-338 cannot have an active Bluetooth connection to your PDA, laptop or Smart phone during this test.)   

3.) Q: On the new BT338 v2 GPS receiver, is it possible for us (not the customer) to open the BT338 and solder a jumper or add a component to the PCB to disable the auto-shut off completely when running on the internal Li-ion battery only?
3.) A: Auto-off feature is controlled by Bluetooth firmware. We can modify the Bluetooth firmware to disable the Auto-off feature when running on Li-ion battery only . It is impossible to perform this feature by soldering a jumper or adding a component on the PCB.

To upgrade the Bluetooth firmware , you need the specific fixture to do the upgrade.  We
often perform the Bluetooth firmware upgrade in the factory.

4.) Q: Do any other Globalsat Bluetooth GPS receivers offer the same auto-shut-off feature as your BT-338 v2?    
4.) A: Yes, our new BT-328 and BT-359 Bluetooth GPS receivers will both function in the same manner for as the v2 BT-338.         

5.) Q: Is this device WAAS enable?
5.) A: Yes, the device is WAAS enabled by default, that are sold by USGlobalSat, Inc and its Authorized Dealers            . Note, receivers with firmware 3.1.1 and above are WAAS enable out of the box.

6.) Q: What datum is used?
6.) A: WGS 84  

7.) Q: Is this device waterproof?   
7.) A: No…       

8.) Q: What's the refresh rate?   
8.) A: GGA(1sec), GSA(5sec), GSV(5sec), RMC(1sec),VTG(1sec)        

9.) Q: How many satellites are needed for 3-D positioning?   
9.) A: A minimum of 4 satellites (3 for 2-D no altitude)          

10.) Q: Can I reconfigure receiver? If so, what program?           
10.) A: Yes. SirfDemo programming utility. Note, custom settings are temporary until the receiver has exhausted both the Li-ion battery and internal Super-Cap back-up power supply.  Then the receiver will revert back to its original default settings.

11.) Q: Can I reconfigure receiver's Baud-Rate? If so, what program?        
11.) A: Yes. SirfDemo programming utility. Note, custom settings are temporary until the receiver has exhausted both the Li-ion battery and internal Super-Cap back-up power supply.  Then the receiver will revert back to its original default settings.

12.) Q: Can I reconfigure receiver's NMEA data? If so, what program?        
12.) A: Yes. SirfDemo programming utility. Note, custom settings are temporary until the receiver has exhausted both the Li-ion battery and internal Super-Cap back-up power supply.  Then the receiver will revert back to its original default settings.

13.) Q: What platforms are supported?     
13.) A: A better answer. Most devices with Bluetooth communication capabilities. (Check Manufacturer Specs)

14.) Q: Once set. Is SiRF Binary Protocol a permanent configuration?
14.) A: These settings are temporary until the receiver has exhausted both the Li-ion battery and internal Super-Cap back-up power supply.  Then the receiver will revert back to its original default settings.          

15.) Q: What is the Blue LED indicator represent?      
15.) A: Bluetooth communication status. Blinking (Slowly)=No Bluetooth connection. Blinking (Quickly)=Bluetooth connection established.    

16.) Q: What is the Yellow LED indicator represent?      
16.) A: Unit is charging with external power plugged in. Red= Needs charging immediately. Yellow= Battery charging.  LED off=Battery fully charge.   

17.) Q: What is the Green LED indicator represent?      
17.) A: Satellite status. Green LED Flashing=GPS position is fixed. Green LED Steady= No GPS position is fixed and searching.       

18.) Q: My GPS shuts down after a period of time. Why?
18.) A: This unit is programmed to shut off automatically after 10 minutes if not communicating with another Bluetooth device.

19.) Q: What's the unit's Bluetooth transmission radius?
19.) A: Ten meters (10m) is unit's maximum Bluetooth transmission radius.

20.) Q: What's the unit's charging current draw? When Off? When On?      
20.) A: When "Off" approximately 150mA. When "On" approximately 200mA.          

21.) Q: What's the unit's Baud Rate settings? 
21.) A: 38400 bps     

22.) Q: When I turn the power on, does it actually start the GPS or the BT module?   
22.) A: Both start at the same time, if no BT connection is made within ten minutes, then both will turn off.          

23.) Q: How does the "20 channel" affect performance? Both: MR350 and BT-338 have "20 channel" in the specs?
23.) A: The sensitivity numbers like the TTFF numbers don't really mean much, as they're hard to tie into real life observations.  

24.) Q: How much more is the SiRF Star III power consumption compare to SiRF Star IIe/LP?
24.) A: About 15% more power hungry than the previous SiRF Star IIe/LP.     

25.) Q: Is SiRF Star III quicker in signal acquisition?    
25.) A: Yes, SiRFStarIII can acquire much faster than IIe/XT2 in difficult environments thanks to the added correlating power and that is not reflected in the dB number.    

26.) Q: What are the charger's electrical specifications (voltage, amps, pin size, etc) for this unit?        
26.) A: 4.6 / 6V @ 1A - 3.5mm iPAQ power jack     

27.) Q: Can I disable the auto-off feature?          
27.) A: Unfortunately, it’s a standard programmed feature to conserve battery energy.

28.) Q: How much accuracy is comprised without utilizing WAAS?          
28.) A: Since Selective Availability (SA) was removed in May 2000, the residual GPS error of approximately 10 meters is mostly due to GPS signal deflection that the SBAS system can only marginally correct (I have never been able to measure any improvement from EGNOS but others have seen 1/2 meters with WAAS). On the other hand SBAS is crucial for critical use such as flying a plane as it allows for near real time GPS signal integrity checking.        

29.) Q: What is the biggest benefit of the SiRF Star III chipset?          
29.) A: Correlation power, the action of analyzing the signal received from the satellites and making sense out of it to compute a position. Sounds simple enough, but the signals are very weak (sent from 20,000 kms above our heads) and generally very degraded by our immediate environment, so the more correlation power you have the better your chances are of getting a "fix". In addition, TTFF is less dependent on the environment and once you get a lock you rarely lose it, even indoors. With SiRFIII, GPS requires less "work", for instance, you no longer need to choose between waiting 2 minutes when you leave a parking garage in the morning to get a fix or risk driving around for 10 minutes without one, now you'll generally get a fix in 45 seconds in both situations .          

30.) Q: Does the BT-338 supports multiple bonding/pairing so it can be used with more than one Bluetooth partner at the same time?     
30.) A: Unfortunately, it does not support this feature.           

31.) Q: What is the output format for this receiver?         
31.) A: Output format: GGA(1sec), GSA(5sec), GSV(5sec), RMC(1sec),VTG(1sec)        

32.) Q: What is the current BT-338 firmware version?          
32.) A: Firmware version 3.1.1 is the current BT-338 firmware version.          

33.) Q: Will my receiver support older NMEA standards?      
33.) A: Yes, NMEA 2.0 is backwards compatible with older versions of the protocol. NOTE:  If your map software (such as Street Atlas 5) requires data    
sentence GGA, and your GPS (such as the Magellan 3000) does not           
output GGA, then they will NOT work together.         

34.) Q: Why is my GEOID and mean sea level is missing which affects the altitude calculations?   
34.) A: Yes, the GEOID correction was missing until it was added in version 3.1 of the firmware from my observations of the Holux 236 that uses it.        

35.) Q: What is the meaning of "baud rate"?   
35.) A: Baud rate is really the rate of bit transitions on the serial data link. Since each byte of data adds a start and stop bit, it is 10 bits long, and 38400 baud is 3840 bytes per second. Faster bit rates transfer more bytes per second, i.e., greater bandwidth.     

36.) Q:What to look for first to know which SiRF firmware version is oldest/newest?
36.) A: Here's a little insight into SiRF version numbers: 2.3.2-GSW2-2.05.024-C1PROD1.0_6A -- the GSW2 means standard SiRFstarII software, and 2.3.2 is the release version number. The 2.05.024 or similar numbers are internal numbers into the engineering data base. C1 is the build variant, a number that varies with each software type, but can relate to flash builds vs. RAM (debug) builds, builds with or without SBAS support (WAAS), builds with one or two serial port support, NMEA or binary protocol default, etc. Prod means this is a released rather than a beta (test) version. 1.00 means the release is without any post-release bug fixes. If there is a letter or letters after the Prod1.00, like Prod1.02b, this would mean that some specific "patches" have been added to provide interim fixes for known bugs. After that, anything on the line is likely added by the manufacturer for internal version control. A number like 0000003729 with XMitac2.0 means this is XTrac 2.0 customized by SiRF for Mitac. In general, an X in the number will imply XTrac software, while GSW2 or GSW3 will indicate standard code for SiRFstarII or SiRFstarIII, respectively.  

37.) Q: Can we upgrade our SiRF firmware? What' s needed for the process?         
37.) A: SiRF provides the new versions to our direct customers, but it is up to them to determine if they want to provide an update mechanism to their end-user customers. While the process is relatively simple, unless there is a hardware way to put the receiver into flash upgrade mode (internal boot mode is our term) there is a chance to get things stuck so you have to send it back to the manufacturer or a repair depot to recover. Further, you must be supplied with a flash programming utility to do the job since you cannot access the flash directly -- you have to go through the ARM processor on the SiRF chipset."

38.) Q: What are the differences between the BT-338_GSW3V3.1.1LowV_F-GPS-03-0506222  vs.  BT-338_GSW3.1.1TO_F-GPS-03-0510032?  
38.) A: The difference is we add the RTC time to 1 day, compared with older version 2.5hrs. It will keep the data we stored within 1 day so that no need to do Cold start.

39.) Q: What is static navigation?     
39.) A: Static navigation when enable, velocities lower than 1.2 m/s for 3 seconds we will freeze the position, and leave them frozen until velocity exceeds 1.4 m/s. Static navigation is a mode designed for motor vehicles, which causes the position to become pinned at one location when velocity is determined to be low enough. This is designed to make navigation systems operate more reasonably when the GPS Selective Availability (SA) signal degradation is turned on.       

40.) Q: What is the power consumption for this device?
40.) A: The Power Consumption Rate of BT-338: - Working: 110 mA ~ 120 mA  - Standby:  130 mA ~ 140 mA (Bluetooth consumes more)  

41.) Q: Why is my GPS receiver detected by Bluetooth but no communication is being established to GPSInfo or my third party mapping application?   
41.) A: Some BT-338 receivers have been found with the NMEA protocol disable. You may consider using a Bluetooth enabled notebook or desktop and SirfDemo program to switch the receiver back into NMEA mode. If problems persists, continue by removing  rechargeable battery for a period of 1-3 hours. This action allows the device to reset.

42.) Q: Why is my date stamp data showing "1985 or 2085"?
42.) A: If your receiver date stamp data shows 2085/09/12 or just 85/09/12. The difference is that 1985 is what the date would be if the receiver thought it was first cycle of GPS weeks rather than the current second cycle (1985/09/12 + 1024 weeks = 2005/04/28). To reset, simply remove rechargeable battery for a period of 20 minutes.

43.) Q: What can I do to prevent my device from having GRMC NMEA time stamp data problem?
43.) A: There is backed battery for SRAM and RTC (Real-Time Clock) to keep last stored position , date ,time , satellite data. When you power down GPS , backed battery will keep the last data. It can help us to achieve maximum acquisition performance. After a long period of time (about 4 hours, depend on different products) GPS is power off, backed battery will run out and last stored data will lose. When you re-start GPS , last stored data display at first if backed battery is still active. If backed battery is inactive , default parameters will display. Only after new GPS signals are received , correct data will display. It can explain why incorrect date display at first. In short ,  the receiver requires GPS data to update these parameters.    

44.) Q: After performing the above. Why is the device's GRMC NMEA time stamp data still incorrect?
44.) A: To correct this problem, remove battery for a period of 10-30 minutes… 

45.) Q: Why does my receiver fail to acquire satellite information after in use from a flight?  
45.) A: Under GPSInfo, perform a cold start. In result, the BT-338 will reset its registers for terrestrial coordinate calculation.     

46.) Q: Why is the power consumption greater in Standby?        
46.) A: In the Bluetooth specification the Working Mode uesd 30-40 mA to communication. But the Stand-by Mode used 50-60 mA to search for Bluetooth device all the time . So it need more power then Working Mode. For the reason we made the "auto-power off" function. Once BT-338 exceeds the 10 minute "Stand-by" mark, unit will automatically shut itself down.

47.) Q: What are the differences from SiRF Binary Protocol for SSII SSIII manuals?        
47.) A: Key differences between SS2 and SS3 binary is that SS3 no longer uses as many debug messages (Message ID 255), and instead uses a newer message 225. That message has sub-message IDs, most of which are not defined outside our Engineering department. Sub-ID 6, however, is the TTFF message, which may be of interest. Message 225 is turned on and off just like message 255: use the debug/development message flag in the reset configuration byte of the reset message (message 128).

48.) Q: What the official time is required to fully charge the unit from having the red led flashing?   
48.) A: Three to four hours      

49.) Q: How important is having WAAS enabled on your GPS receiver?         
49.) A: SiRFstartIII currently does not have WAAS enabled, not that this matters unless you intend on relying on it to operate a plane. 

50.) Q: What satellite identification number is used for WAAS and EGNOS?
50.) A: Satellite #33 (AoRE) is for EGNOS, Satellite #35 (AoRW) is for WAAS, and it has been suggested that Satellite #41 (PoR) will be used to indicate that data is being received from the Japanese MSAS system.

51.) Q: What is trickle mode?  
51.) A: The Trickle mode allows for an increase in battery life by putting the GPS module in sleep mode for very short periods of time, such as 300ms per 1s cycle, which will result in a battery life increase of about 40% according to my testing. It can be useful for certain types of applications but there is a hit on performance as the receiver will have to get "back on its feet" when it wakes up. It is especially problematic in difficult reception conditions. Starting with FW 2.3, SiRF has added the "Adaptive Trickle" mode, which as its name implies will adapt the power savings to the conditions of reception. In optimal conditions, I found that the battery life increase amounts to about 30%.     

52.) Q: What is needed for Tom Tom Navigator to see my BT-338 receiver?
52.) A: Go to Bluetooth settings, advanced, services, serial port, and make a note of the outgoing port - that's the one you need to use. In Bluetooth manager, I'm sure you have connected to the SPP service of the receiver. Pairing is nice, but not required. In Bluetooth Manager search for new devices, once it found the BT-338, tap it to find the available services. Find the SPP service and connect to it. TomTom Navigator needs BT-338 to be selected as an "Other cable NMEA GPS receiver" instead of "Other Bluetooth GPS receiver".  Once this is performed TomTom Navigator will be able to "see" the BT-338 GPS device.  The problem lays with the TomTom software, not with the BT-338.

53.) Q: Cannot connect to BT-338. When doing a discover i see the BT-338. But i cannot establish a serial connection. What I can do?  
53.) A: Change original microsoft windows XP bluetooth stack. Instead of the stack provided from IBM ( widcomm )

54.) Q: Lately it takes too long to lock the satellites. Sometimes it took as long as 7-9 minutes (solid green LED). Environment: highway, no high trees and buildings. What can I do to correct this?
54.) A: Remove rechargeable battery for 1-3 hour period.

55.) Q: Why am I not getting any or very weak GPS signals even though my GPS receiver is directly under the windshield glass?
55.) A: Certain vehicles may be equipped with special windshields that contain metal in the glass that prevents GPS and RF signals from being received properly. Customers with these types of windshields must use an exterior GPS antenna for improved results for GPS applications. If you are unsure about whether your vehicle has one of these types of windshields, contact your dealer and request more information. This vehicle list may not be complete and may updated from time-to-time.


56.) Q: The unit cannot be powered on by battery no matter how long I charged the battery. What can I do to correct the problem?
56.) A: Be certain all three BT338 battery cooper contacts are mating with rechargeable battery.

57.) Q: The battery light didn't turn orange while the unit was being charged.  What can I do to correct this problem?
57.) A: If you are using the DC charger check for an open (blown) fuse. In the other hand, if you are using the AC charger connect a different device that supports this voltage to confirm its functionality.

58.) Q: How do I connect and use a Bluetooth GPS device with Windows?      
58.) A: In order to set up a Bluetooth Connection with a GPS receiver, please follow these steps...  

59.) Q: How do I connect and use a Bluetooth GPS device with Mac?      
59.) A: In order to set up a Bluetooth Connection with a GPS receiver, please follow these steps...  

60.) Q: How do I connect and use a Bluetooth GPS device Pocket PC?    
60.) A: In order to set up a Bluetooth Connection with a GPS receiver, please follow these steps...  

61.) Q: How do I connect and use a Bluetooth GPS device Palm?
61.) A: In order to set up a Bluetooth Connection with a GPS receiver, please follow these steps...  

62.) Q: How do I connect and use a Bluetooth GPS device WinMobile5?
62.) A: In order to set a Bluetooth Connection with a GPS receiver, please follow these steps...

63.) Q: There is a "?" over the gps icon and I am not allowed to enter a security code. when opening third party software the gps is detected. What can I do to correct this?
63.) A:
Disregard the GPS icon question mark and proceed with the pairing process. Worst case, perform a device reset.

64.) Q: What is the device’s passkey?
64.) A: The device’s passkey is “0000”.

65.) Q: Can I alter the GPS datum?
65.) A: Unfortunately, you cannot alter the GPS datum.

66.) Q: After changing my GPS receiver to send data to my PC in SiRF format, which was configured using the included SiRFDemo utility program, my GPS receiver's LED is now very dim and no longer is sending data to my mapping application.            What can I do to correct this?
66.) A: First... you are required to download SiRF Demo programming utility here

Once this program is downloaded and installed on your laptop or desktop machine, you may proceed executing the following instructions listed below. 

1. Select "OK" on the Data Source Setup.
2. Mirrored Serial Port and Baud Rate settings found in Device Manager ( Device Manager information can be accessed from Start->Control Panel->System->Hardware->Device Manager-> Ports->
For Compact F: Compact Flash OX16CF950 (Com X) 
For USB: Prolific USB-to-Serial Comm Port (COM X)
3. Then, select "Action" followed by "Open Data Source". 
4. Select "Action" followed by "Switch to NMEA Protocol".
5. Finally, at this step click "Send".
6. Exit the program.