GlobalSat BU-353 gps receiver

Product details on the vendor's web page.

Well, this is my first experience with GPS receivers, so I am not in a position to compare performance with any other receiver. The general opinion, from the countless reviews in the Net, is that is very sensitive and fast to fix the position.

My intention is to use the receiver with my Eee PC 901 in the rare occasions when I need a GPS navigator or rather as a small home project.

First impressions: smaller than what I was expecting from the pictures, reasonable length of the cable (1.5 m), time to fix from cold start 15~20 minutes from inside the room in my apartment and about 4~5 minutes in a car.

Under Windows XP the initial setup is quite simple. There is a small standard tool provided on the installation disk "GPS Info" that can connect to the virtual serial COM port and communicate with the receiver - excellent to check on the status of the module.

Under Linux, most probably you will need "gpsd" to communicate with the device. I have installed "GPSDrive" from synaptic that has also pulled all the necessary dependencies including gpsd.

WARNING:(read this before you experiment yourself). I have used EeeBuntu 2.0 that has the necessary modules but for one or another reason does not starts the gpsd daemon when you insert the USB. This is not a serious problem, since as user one can easily start the program with: gpsd -bnN -D 2 /dev/ttyUSB0 . DO NOT forget the "-b" OPTION!!! From the gpsd man page

-b

Broken-device-safety, otherwise known as read-only mode. Some popular bluetooth and USB receivers lock up or become totally inaccessible when probed or reconfigured. This switch prevents gpsd from writing to a receiver. This means that gpsd cannot configure the receiver for optimal performance, but it also means that gpsd cannot break the receiver. A better solution would be for bluetooth to not be so fragile. A platform independent method to identify serial-over-bluetooth devices would also be nice.

And this is the whole story... I have managed to lock my device the very first time I have tested it under Linux (didn't use the "-b" option). It became almost inaccessible. "GPS Info" was showing garbled output while the led remained off. I have almost accepted the damage since 5 minutes without power did not help. A suggestion on the net says that it needs 72 hours to drain completely and reset. The better solution: Under Linux, start gsmd with the "-b" option. Then connect to the the daemon by "telnet localhost 2947" and then type "n=0" to set the sirf-III chip or firmware to output NMEA strings only. Here is the original post of the solution.

The common tools, to get some info from the GPS receiver under Linux are:

xgps: simple test client for gpsd with an X interface. It displays current GPS position/time/velocity information and (for GPSes that support the feature) the locations of accessible satellites.

cgps: client resembling xgps, but without the pictorial satellite display and able to run on a serial terminal or terminal emulator.

as well as xgpsspeed, gpxlogger, cgpxlogger etc.

GRT815M - Ubuntu 8.04 (Hardy Heron)

In general the distribution works out of the box. Just a few hints to make your life easier and your computer running smoother.

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1. To disable the annoying BIOS bug at the boot screen, add noapic in /boot/grub/menu.lst (leave the # sign intact)

# defoptions=quiet splash noapic

you can add vga=791 to the same line to get nicer text console and then run update-grub to apply the changes.

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2. To get your the NVidia drivers running properly (almost) edit the following files:

/etc/modprobe.d/blacklist: add these two lines

blacklist agpgart
blacklist sis_agp

/etc/modprobe.d/nvidia-kernel-nkc: add these two lines (the second is just in case)

options nvidia_new  NVreg_EnableAGPFW=1 NVreg_EnableAGPSBA=1
options nvidia      NVreg_EnableAGPFW=1 NVreg_EnableAGPSBA=1

Restart the computer to give up on sis_agp module, then you will get the following result:
cat /proc/driver/nvidia/agp/status

Status:          Enabled
Driver:          NVIDIA
AGP Rate:        8x
Fast Writes:     Enabled
SBA:             Enabled

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3. If you want to be able to throttle your CPU, replace powerd with cpufreqd (cpufrequtils) then add p4_clockmod option module in /etc/default/cpufreqd:

CPUFREQ_CPU_MODULE="p4_clockmod"

Comment the line "#MODULE=speedstep-ich;" and add new "MODULE=p4-clockmod;" in /etc/init.d/loadcpufreq

    # Right. Check if it's a P4 without est.
    # Could be speedstep-ich, or could be p4-clockmod.
    #MODULE=speedstep-ich;
    MODULE=p4-clockmod;
    # Disabled for now - the latency tends to be bad
    # enough to make it fairly pointless.

To be able to alter the frequencies I have made this change in /etc/cpufreqd.conf

[Profile]
name=Performance High
minfreq=20%
maxfreq=100%
policy=performance
#exec_post=echo 8 > /proc/acpi/sony/brightness
[/Profile]

Restart the daemon.
sudo /etc/init.d/cpufreqd restart

You can add the "CPU scaling monitor" applet to the Gnome panel but to be able to use it as user run the following command:

sudo chmod +s /usr/bin/cpufreq-selector

Alternatively, use the following commands to alter the parameters: cpufreq-info, cpufreq-selector, cpufreq-set. I was not able to find convenient GUI tool that will do it from the tray but hey - it works.

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4. If you find your hard disk clicking - here are some setting to alter to solve the problem.

/etc/hdparm.conf: set ROOTFS = /dev/sda and add these lines at the end of the file.

/dev/sda {
apm = 254
}

/etc/apm/event.d/20hdparm: uncomment the line #APMD_DRIVES=

APMD_DRIVES=

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Here is a table of VESA video modes (VGA codes):

         640x480   800x600   1024x768   1280x1024   1600x1200   Ask user at boot.
8 bits   vga=769   vga=771   vga=773    vga=775     vga=796     vga=ask
16 bits  vga=785   vga=788   vga=791    vga=794     vga=798     vga=ask
32 bits  vga=786   vga=789   vga=792    vga=795     vga=799     vga=ask

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If you know how to make the computer SUSPEND - please let me know.