The MT8221B BTS Master is available with a built‑in GPS receiver (Option 31) that can provide latitude, longitude, altitude, and UTC timing information. This option also enhances frequency reference oscillator accuracy.
Activating the GPS feature:
1. Attach the GPS antenna to the GPS Antenna connector on the top of the instrument.
Note
The GPS antenna connection on the BTS Master is fitted with an SMA connector. You can use the GPS menu to select + 3.3 VDC or + 5 VDC. The default selection is always + 3.3 VDC.
Caution
Check the voltage setting before connecting your antenna.
2. Press the Shift key then the System (8) key on the numeric keypad to display the System menu.
3. Press the GPS submenu key to display the GPS menu (refer to GPS Menu).
4. Activate GPS by pressing the GPS, On/Off submenu key so that On is underlined. When GPS is first turned On, the GPS icon is displayed in red.
GPS Icon, Red
5. Press the GPS Info submenu key to open the GPS Info window, which displays:
a. Tracked Satellites
b. Latitude
c. Longitude
d. Altitude
e. UTC timing information
f. Fix available
g. Antenna Status
h. Receiver Status
i. Antenna Voltage
j. Current Draw
When the GPS receiver is tracking at least 3 satellites, the GPS icon changes to green.
GPS Icon, Green
Note
As long as 3 minutes may be required for the Ref Freq status to change to GPS High Accuracy in the Status menu, which is displayed on the left side of the measurement display.
To reset the GPS, press the Reset submenu key. The green GPS icon with a red cross appears when GPS satellite tracking is lost (refer to Figure: GPS Icon, Green with Red Cross). This occurs after being active (tracking three or more satellites).
GPS Icon, Green with Red Cross
After GPS location Fix is attained, the internal reference oscillator begins to correct its frequency to match the GPS standard. After the internal frequency is adjusted to match the GPS standard, the status is indicated by “GPS High Accuracy” showing in the Status menu, which is displayed on the left side of the measurement display. When the GPS feature is not enabled, the reference source displays either “Internal Standard Accuracy” or a user-selected external reference frequency in the Status menu.
Within three minutes of satellite acquisition, the reference oscillator will have an accuracy of better than 25 ppb (parts per billion). The OCXO internal standard accuracy is ± 0.3 PPM. The correction factor applied to the internal OCXO allows the instrument to maintain GPS frequency accuracy for three days at better than 50 ppb, even when the instrument is obstructed from receiving signals from the GPS satellites.
In order to acquire data from the GPS satellites, you must have line‑of‑sight to the satellites, or the antenna must be placed outside with no obstructions.
The 2000‑1528‑R GPS Antenna with 5 meter cable is a required accessory (unless you already have a GPS antenna with an SMA connector).
