Troubleshooting AltaCom2

Weather Readings and Calibration

(AC2)Crazy Date

Paging Problems

Computer and Software

Weather Readings and Calibration

Help! My weather readings are off!

The problem is usually NOT a calibration problem. First off determine which sensor or sensors are not reporting correctly. If a calculated value such as Adjusted Altitude or Grains is off, the cause will be found by looking at the Temperature, Relative Humidity or Barometric Pressure readings.

The barometric pressure sensor is located in the console, if it is reading low the most likely cause is insufficient power to the console caused by:

  1. weak battery in your 12 volt supply
  2. broken 110v power supply
  3. using the wrong power supply (correct is 15v 2.65 A)
  4. mis-calibration

If both Temp and RH are off, or one is slightly off, or if  Temp or RH is pegged (Temp at or near 125 degrees and RH at 100%)  the most likely problem is in the remote sensor cable or cable connections:

  1. Bent, damaged, or missing pins in the male connectors, metal debris in the male or female cable ends
  2. Moisture wicking into the remote sensor cable ends or corrosion
  3. a short or damage to the remote sensor cable ends (inspect the pins)
  4. missing/detached cable ground (readings will be elevated and fluctuate)
  5. using the wrong cable (one not purchased from us or a dealer)
  6. Remote Sensor fan not running

If you have 2 cables in series, with or without a connector panel, try using just one cable and then the other, or borrow a cable to see if that isolates where the problem is. These may help:

We have seen customers substitute a store bought serial cable for the remote sensor cable we sell. Even if it claims to be shielded and grounded, it will not have adequate ground for your needs.

Over time, (years) the RH sensor will tend to read high and not read fully down to the low end of its range. It should be replaced.

My weatherstation doesn’t match the other guy’s.

There are many reasons your weatherstation may not match someone else’s. Different weatherstation manufacturers use different formulas to calculate values. A digital instrument may have a different range than analog gauges. Some weatherstations are designed for racing while others are desktop instruments. There are micro climates in any environment, so a weatherstation near the finish line may not read the same as one located differently

You should expect accuracy in your weatherstation, and if you suspect mis-calibration get it corrected. Keep in mind that some important aspects of weatherstation performance such as repeatability, cannot be determined through comparison. The final test of any racing weatherstation is whether or not it is working for you, allowing accurate predictions and reliable tuning. The most important aspect for racers is repeatability, and minor differences between stations can be acceptable.

When comparing your instrument to someone else’s be sure to let the weather stations settle in the same location for 10 minutes or so before checking the readings. If a friend’s weatherstation has been in the in the sun for 5 minutes, and you try to compare it to a weatherstation that’s been in the shade there will be a difference caused by those different conditions.

Be specific about what readings are different. Let’s look first at the measured readings.

A difference in barometer reading could be caused by:

  1. One is absolute and one is sea level.
  2. Some companies scale their digital barometers light by 25% over full scale range. We don’t. You would see more of a difference at higher altitudes.
  3. Some digital barometers may not have adequate temperature compensation, so if you are comparing them at high or low temperatures the uncompensated barometer will read higher.
  4. Note that an analog barometer may have drifted due to vibration or being bumped, but it will still show the same amount of change even it an incorrect setting.

A difference in temperature could be caused by:

  1. The gauges have not settled together long enough. The larger and heavier the instrument, the longer it will take to settle.
  2. Comparing at too extreme a temperature (less than 30 degrees or more than 90). A desktop model will not be accurate at the highs and lows.
  3. Some digital temperature sensors are less linear than other types.

A difference in relative humidity could be caused by:

  1. One point versus multi-point calibration. Altalab provides multi-point calibration to keep the RH sensor accurate full scale, some other instruments are calibrated at only one point. Think of this as trying to keep a long heavy board level. It’s much more reliable to use multiple supports than one.
  2. Difference in sensor accuracy.
  3. Sensor age differences (older sensors will tend to read higher)

If the measured readings are different then it is likely the calculated values will also be different, after all, the measured values are the starting point. The biggest difference us usually between weatherstations that provide Adjusted Altitude and those which provide Density Altitude.

How do I calibrate my weatherstation?

Call us. Mis-calibration is not usually the cause of bad readings, and trying calibration to fix a hardware problem will make things worse. But if you must, use ACLive in the Merlin program to adjust calibration.

How can I check barometer calibration?

You can call a local airport and ask for Station Pressure which is the same as absolute. There may be a slight elevation difference between the track and the airport (roughly 1″ Hg per 1000′ of elevation).

Will it hurt the remote to get rained on?

No, but it is not ideal. The worst that can happen is the RH sensor will become saturated and take time to dry out. Turn off the weatherstation if it rains, to prevent the fan from pulling moisture inside. If the RH sensor does get saturated, put the remote inside a dry warm place and let AltaCom II run until the sensor reads normally.

Should I build a roof or sunshade for the remote?

Not necessary, the remote comes with an aluminum shield. You would not want to add anything that would trap air, such as a four-sided enclosure.

Crazy Date

Crazy Date is a serious weatherstation condition that can be managed in the field until the you can return your Alta or AltaCom II for backup clock battery replacement. Here’s what you should know to best manage Crazy Date until you can send your station in for repair.

What Crazy Date look like:
Date and time are wrong, often impossibly wrong (9/01/00 255:000 for example). The consequences of Crazy Date may include:
“locking up” when the console transmits once on startup, but then doesn’t update the weather or transmit on schedule after that.
Even after resetting, time and date revert or stop advancing when the station is turned off.

You may see that the station locks up and you have to turn it off and back on to get a page. You may notice that the weather readings are wrong, not updating, or old.

Permanent fix – Send in your console in for backup battery replacement, (it cannot be done in the field).

Temporary fix – After starting the weatherstation, use Merlin to set the time and date.

Slightly better Temporary fix – install the latest Merlin (Merlin currently available on our website). Connect to the weatherstation, Launch Merlin > Click Tools > Preferences and choose Yes in the Set Time dropdown. Then click Export. This tells Merlin to AUTOMATICALLY set the time and date on launch, a time and keystroke saver for a racer who cannot spare the time to send in the weatherstation.


Help, I am only getting pages close to the trailer, or transmissions are garbled.

Paging draws the most power of any weatherstation function. Check these potential causes:

  1. weak battery in your 12 volt supply
  2. broken 110v power supply
  3. using the wrong power supply (correct is 15v 2.65 A)
  4. transmitter (in console) is weak and needs repair or replacement
  5. pager needs repair
  6. antenna is damaged or broken
  7. antenna not connected (will damage the transmitter)

Help, I am not getting any pages.

If your paging worked in the past, any of the causes of weak paging above could be the culprit. In addition:

  1. Transmitter needs repair or replacement
  2. Carrier Detect is continuously ON (red light on console) because of local interference
  3. Carrier Detect is continuously ON (red light on console)because internal radio cable has become detached from the board

If your station is brand new and has never paged we could also look at these possibilities:

  1. pager and console mis-matched (can be fixed over the phone)
  2. internal radio cable disconnected from the board
  3. automatic paging turned OFF in Merlin

I receive regular pages from the weatherstation but not from Crew-Chief or Alta Weather (or any other third party software vendor).

Call us, we can help you determine if this is a hardware problem or a problem with another vendor’s software. Hardware problems include:

  1. USB to Serial Adapter not installed with the correct driver (look for it to be listed under Ports in the device manager)
  2. faulty serial or USB to serial adapter cable
  3. connecting to the wrong port on the AltaCom II console (should be serial 25 pin to 9 pin attaching to USB to Serial 9 pin to usb)

(AC2 only) I am getting pages from the weatherstation and from Crew-Chief or Alta Weather (or any other third party software vendor). Can I turn off the regular weatherstation pages?

Yes. In Merlin Preferences, uncheck all weather variables except wind and ambient light and click Export.

Computer and Software

Help! I can’t connect to Merlin

Merlin 8 is compatible with Windows XP, 7, 8, 10 and 11. We do not support Windows Vista. Make sure you have a compatible operating system and the latest version of Merlin. Registered Users can Download Merlin here.

  • What Racers Say:

    "Your weatherstation has been very reliable and made life a lot simpler." Debbie Rothermel and Chuck Rothermel S/G NHRA Division 1