Locking onto Radiosonde in Non-Overhead Conditions
Radiosonde position below 60 degrees elevation
After Baseline and Prior to Release
1. Point TRS in the direction the wind is expected to take the balloon in five minutes.
Reminder: The TRS tracking position is 180° out from the wind direction.
2. Leave the TRS in Manual track mode
3. If required, contact air traffic control tower.
Release balloon in accordance with WSOH-10
At the CDU (within five minutes after release)
1. Manually Point or Slew the TRS toward the radiosonde.
2. Engage Auto track mode.
o WATRACK or TRACK = Auto on the CDU
3. Use the Signal Strength and Az./Elev. errors indicated on the CDU to confirm the TRS is tracking.
o Signal strength should increase.
o Az./Elev. errors should decrease.
If the antenna appears not to be tracking the radiosonde or is erratic
If conditions prohibit locking onto the radiosonde using the CDU, the observer may use the RWS GPS Search.
Locking onto the radiosonde in Overhead Conditions
Use when overhead conditions (light winds) is expected.
The TRS can track radiosondes in overhead conditions, once the radiosonde has risen a significant distance from the surface (approximately 5000 ft AGL or 5 minutes), such that minor radiosonde movements (such as the pendulum motion of the radiosonde) do not incur large changes in azimuth (which are likely to produce over-current errors).
If during the time of release, light winds are expected to occur below 5000 ft AGL (overhead conditions) OR the radiosonde is expected to cross directly over the TRS below 5000 ft AGL, the observer should be aware of the potential for TRS over-current errors. The over-current errors (MCU 0x0800 in the RWS Hardware Status Display) indicate the TRS is accelerating too rapidly. These errors most commonly occur during the first five minutes of an overhead flight and only while in WAGS. Once five or more over-current errors occur in rapid succession, the TRS will turn off the affected motor to protect it from damage and suspend tracking in that axis. If less than five over-current errors occur, placing the TRS in Manual for 20 seconds will reduce the likelihood the TRS will lockup due to multiple over-currents.
After Baseline and Prior to Release
1. Point TRS in the direction the wind is expected to take the balloon in five minutes.
Reminder: The TRS tracking position is 180° out from the wind direction.
2. Leave the TRS in Manual track mode
3. If required, contact air traffic control tower.
Release balloon in accordance with WSOH-10
At the CDU (within five minutes after release)
1. Manually Point or Slew the TRS toward the radiosonde.
2. Continue to Point or Slew the TRS until one of the following occurs:
o Radiosonde has risen a significant distance from the surface (at least 5 minutes/5000 ft AGL), such that minor radiosonde movements (i.e. pendulum motion) do not incur large changes in azimuth.
o Radiosonde has been carried downrange and is no longer in overhead conditions.
3. Manually Point or Slew the TRS toward the radiosonde.
4. Engage Auto track mode. WATRACK or TRACK = Auto on the CDU
5. Use the Signal Strength and Az./Elev. errors indicated on the CDU to confirm the TRS is tracking.
o Signal strength should increase.
o Az./Elev. errors should decrease.
If the antenna appears not to be tracking the radiosonde or is erratic
Locking onto the radiosonde using the RWS Software
Use when conditions prohibit locking onto the radiosonde using the CDU.
The RWS Software can be used, when conditions prohibit using the CDU to lock on to the radiosonde. The RWS software can control the TRS in a similar manor as the CDU but doesn’t provide the azimuth and elevation errors for use in verifying tracking. The most useful tracking feature is the RWS Search button. When GPS wind data is available (indicated by a green circle and plus “+” sign in the SPS Status Display) the TRS will be commanded to point to the GPS calculated azimuth and elevation (the az/elev columns in the Processed Data Display) and engage Auto track. When GPS wind data is not available (indicated by a red circle and a minus “-” sign) the feature has the same functionality the Limited Search on the CDU.
After Release
1. At the CDU, manually point or slew the TRS toward the projected radiosonde location.
2. Leaving the TRS in Manual track mode.
3. Return to the RWS workstation
In RWS
4. The “Balloon Release Detected” message appears.
5. Click Continue
6. Update Surface observation, if necessary.
7. Click OK
8. Open up the TRS Display
9. Open up the SPS/GPS Status
Assuming GPS wind data is available
1. Click the Search button in the TRS Display.
2. Once Auto track mode is engaged, use the signal strength, GPS calculated Azimuth and Elevation in the PDS along with the trajectory plot to confirm the TRS is tracking.
If GPS wind data is not available
1. In the TRS Display, point the TRS toward anticipated location of the radiosonde.
2. The signal strength should increase.
3. Click the Search button in the TRS Display to initiate a conical search.
4. The TRS will switch into Auto track mode with AFC on if a strong signal is found.
5. If a strong signal isn’t found and the Limited Search fails place the TRS into Manual track mode, reposition the TRS and reattempt.
6. If the TRS switches to a Full Search, immediately place the TRS into Manual.
Manual Tracking after Auto Tracking Failure
Work-around when the TRS fails to track in Auto
This procedure requires GPS wind data.
After Baseline
1. Verify that the Hardware and GPS/SPS Status have all green icons.
2. Point TRS in the direction the wind will take the balloon.
NOTE: The TRS tracking position is 180° out from wind direction.
3. If required, contact air traffic control tower.
At the CDU
1. Check signal strength, antenna position, and re-checking weather conditions prior to release.
2. Call office to verify that GPS is still being received
3. Release balloon in accordance with WSOH-10
4. Leave in Manual track mode.
In RWS
1. Verify the “Balloon Release Detected” message appears.
2. Click “Continue”
3. Update Surface observation, if necessary.
4. Open up the Processed Tabular Display
5. Scroll to the latest Azimuth and Elevation position.
6. Enter the latest Azimuth and Elevation position into the TRS Display and click “Move Antenna”.
7. Verify the signal strength has increased.
8. Monitor the flight every 5 minutes to ensure proper signal strength and TRS antenna position
a. Repeat steps 5 & 7 as necessary.
Reacquiring the Radiosonde after Resetting the TRS
Use after resetting the TRS after Over-Current lockup (five or more consecutive MCU: 0x0800 errors)
1. Wait until the TRS has completed its “initialization” process.
a. “TRS is Ready” appears in the TRS Display Status.
2. Set the TRS to the radiosonde frequency and turn AFC ON.
3. Open up the Processed Tabular Display.
4. Scroll to the latest Azimuth and Elevation position.
5. Enter the latest Azimuth and Elevation position into the TRS Display and click “Move Antenna”.
6. Verify the signal strength has increased.
7. Once the TRS has moved, select the “Search” track mode in the TRS Display.
8. The TRS should lock on and switch into “AUTO” Track mode with AFC On, after a successful search has been completed.
9. If the TRS doesn’t lock on to the radiosonde, repeat steps 5-8.
10. Continue with normal flight operations.