In the above test, the red
represents the old BU-353 S3
unit, and the blue
is the new BU-353 S4
The test was performed in downtown Toronto. The area was chosen because of its traditionally difficult environment for GPS navigation due to very tall buildings surrounding narrow streets.
Both receivers were placed on the roof of the vehicle, approximately 30 cm (1 ft) apart, and the testing of both units was performed simultaneously.
Notice that the blue line (the new S4) tracks the road more closely than the red line (the old S3). This difference can really be only observed in very difficult environments.
The new BU-353 S4 had a fix on one or two more satellites during the test than the S3 version.
The old version has received very positive feedback from many users over the past few years, some of which can be read here: http://www.laptopgpsworld.com/4800-globalsat-bu-353-usb-gps-receiver
The new version of the receiver works just like the old version, and it even adds a bit more precision when used while navigating in difficult environments. This may be partly due to the improved sensitivity of the SS4 chip, -163dBm, versus the SS3, -159dBm.
Electrical Characteristics (Receiver)
GPS Chipset : SiRF STAR IV GSD4e
Frequency : L1, 1575.42 MHZ
C/A Code : 1.023 MHz chip rate
Channels : 48
Sensitivity : -163dBm
Position Horizontal : <2.5m 2D RMS SBAS Enable
Velocity : 0.1m/sec 95% (SA off),
Time : 1 micro-second synchronized to GPS time
WAAS : Enabled for North America product s (USGlobalSat, Inc)
Datum : WGS-84
Hot start : 8 sec., average
Warm start : 35 sec., average
Cold start : 35 sec., average
Reacquisition : 0.1 sec. average
GPS Protocol Default :
NMEA 0183 (Secondary: SiRF binary)
SiRF binary >> position, velocity, altitude, status and control
NMEA 0183 MEA0183 V3.0 protocol, and supports
GPS Output Data : command GGA, GSA, GSV, RMC, VTG, GLL v2.2 (VTG and GLL are optional)
GPS transfer rate : Software command setting (Default : 4800,n,8,1 for NMEA )
Acceleration : Limit Less than 4g
Altitude Limit : 18,000 meters (60,000 feet) max.
Velocity Limit : 515 meters/sec. (1,000 knots) max.
Jerk Limit : 20 m/sec**3
Operating : -40°~ 80°C
Storage : -40°~ 85°C
Humidity : Up to 95% non-condensing
Voltage : 5V ±5%
Current : 60mA typical
Dimension : 2.32" x 1.65" x 0.82" (59mm x 47mm x 21mm)
USB Cable Length : 60" (152 cm)
Low Noise Amp
Amplifier Gain w/out cable : 27 dB Typical
Filtering : -25dB (+100 MHz)
Output VSWR : 2.0 Max.
Voltage : DC 3 ~ 5.0V
Current : 15mA max @ 5VDC
Several users of the new S4 version of this unit have commented on the faster start up time. This may be due to the following new implementation:
With the SiRF CGEE (Client Generated Extended Ephemeris) technology, has the capability of predicting satellite positions for up to 3 days in advance, and will deliver a CGEE-start time of less than 15 seconds under most conditions without any network assistance. The BU-353-S4's MicroPower mode allows the receiver to stay in a hot start-like condition almost continuously while consuming very little power.