If you are having trouble calibrating your timer, be sure you have constructed and placed RF shielding correctly.
Each node keeps track of the signal strength (RSSI) on a selected frequency and uses this relative strength to determine whether a transmitter is near the timing gate. The RotorHazard timing system allows you to calibrate each node individually so that you can compensate for the behavior and hardware differences across your system and environment.
A node can be Crossing or Clear. If a node is Clear, the system believes a transmitter is not near the timing gate because the RSSI is low. If it is Crossing, the system believes a transmitter is passing by the timing gate because the RSSI is high. A lap pass will be recorded once the Crossing is finished and the system returns to Clear.
RSSI during a race appears similar to this graph with many visible peaks and valleys. As the transmitter nears the timing gate, the signal rises.
Two parameters that affect the Crossing status: EnterAt and ExitAt.
The system will switch to Crossing when RSSI raises to or above this level. It is indicated by a red line.
The system will switch to Clear once the RSSI value drops below this level. It is indicated by an orange line.
In between EnterAt and ExitAt, the system will remain Crossing or Clear depending on its previous state.
Manual calibration mode will always use the EnterAt and ExitAt values provided by the user.
Adaptive calibration mode uses the user-defined points unless there are saved races. When saved races exist, changing heats will initiate a search of previous race data for the best calibration values to use in the upcoming race. These values are copied and replace the current EnterAt and ExitAt values for all nodes. This mode improves calibration as more races are saved if the race director confirms the incoming lap counts or recalculates them through the Marshal page.
At the beginning of a race there can be many quads going through the start gate at the same time, and this can result in lower RSSI values being detected on some of the nodes (which could result in an initial gate pass being missed). To account for this, the following settings may be configured:
Start of race EnterAt/ExitAt lowering amount (percent): Sets the amount that the EnterAt and ExitAt values for all nodes will be reduced, as a percentage. For instance, if 30 (percent) is configured, the EnterAt value will be lowered to a value that is 30% closer to the ExitAt value. (So if EnterAt=90 and ExitAt=80, the EnterAt value will be lowered to 87.) The ExitAt value will be also be lowered by the same amount.
Start of race EnterAt/ExitAt lowering duration (seconds): Sets the maximum amount of time (in seconds) that the EnterAt and ExitAt values will be lowered. If a gate crossing for a node is detected as completed before this time then the EnterAt and ExitAt values for that node will be restored then.
Suggested values are 30 (percent) and 10 (seconds). If either of these settings are configured as zero then the EnterAt and ExitAt values will not be lowered.
Note that on the Marshal page these settings are taken into consideration, so if they are non-zero then the first lap pass on a node may be detected even though the peak RSSI appears to be lower than the EnterAt level displayed.
Before tuning, power up the timer and keep it running for a few minutes to allow the receiver modules to warm up. The RSSI values tend to increase by a few points as the timer heats up.
You can use the Marshal page to tune values visually. Collect data by running a race with a pilot on each channel, then save it. Open the Marshal page and view the race data, adjusting Enter and Exit points until the number of laps is correct. Save the Enter/Exit points to each node to use as calibration for future races.
- Below the peak of all gate crossings
- Above any peak when the transmitter is not near the gate
- Higher than ExitAt
- Below any valleys that occur during a gate crossing
- Above the lowest value seen during any lap
- Lower than EnterAt
ExitAt values set close to EnterAt allow the timer to announce and display laps quickly, but may not prevent multiple laps from being recorded during a single gate pass.
Two laps are recorded. The signal rises above EnterAt and then falls below ExitAt twice, once at each peak. Within these two crossing windows, the timer finds the strongest signal (after noise filtering) to use as the recorded lap time.
The Capture buttons may be used to store the current RSSI reading as the EnterAt or ExitAt value for each node. The values may also be entered and adjusted manually.
Power up a quad on the correct channel and bring it very close to the timer for a few seconds. This will allow the timer to capture the peak RSSI value for that node. This should be done for each node/channel that is being tuned. The peak value will be displayed.
A good starting point for EnterAt is to capture value with a quad about 1.5–3m (5–10 ft) away from the timer.
A good starting point for ExitAt is to capture the value with a quad about 6–9m (20–30 ft) away from the timer.
- A low ExitAt value can still provide accurate timing, but the system will wait longer before announcing laps. A delay in announcing does not affect the accuracy of the timer.
- The Minimum Lap Time setting can be used to prevent extra passes, but might mask crossings that are triggered too early. It is strongly recommended to set the behavior to Highlight (rather than Discard) and review each incidence.
- If you experience timing issues during a race but the RSSI is responding to the pilot's transmitter, do not stop the race. Save the race after it completes and visit the Marshal page. RSSI history is saved and the race can be accurately recalculated with updated tuning values.
Laps are not recorded if RSSI does not reach EnterAt.
- Lower EnterAt
Laps are merged together if ExitAt is too low, because the first lap crossing never completes.
- Raise ExitAt
Extra crossings occur when EnterAt is too low.
- Raise EnterAt until crossings only begin near the timing gate. (Use the Marshal page after saving a race to determine and save the best values.)
Too many laps occur when ExitAt is too close to EnterAt, because laps exit too quickly.
- Raise EnterAt, if possible
- Lower ExitAt
The Minimum Lap Time setting always keeps the first crossing and disards subsequent laps that occur too soon. In many instances, the second crossing is actually correct, such as when a pilot misses the gate and circles back to complete it. It is recommended to leave the Minimum Lap Time behavior at Highlight rather than Discard so that a race organizer can manually review each case.
Lap recording takes a long time to complete if ExitAt is low. This does not affect the accuracy of the recorded time.
- Raise ExitAt
Laps will not register if RSSI never reaches EnterAt.
- Lower EnterAt
Laps will not complete if RSSI never drops below ExitAt.
- Raise ExitAt