This could have several causes and different solutions:

1) Cause:  You are looking at the ‘Short’ (15 second) average in a low radon concentration area. In the 15 second interval, one detected count corresponds to about 350 Bq/m3 or almost 10 pCi/L. So, at low radon concentrations, you can expect the ‘Short’ display to display 0 most of the time, and then jump to 350 or 700 Bq/m3 (10 or 20 pCi/L) when one or 2 alpha particles are detected in the 15 seconds. The ‘Short’ setting is for measuring high levels quickly.

Solution:   At low radon concentrations, the ‘Long’ (5 minute) reading should be used.

2) Cause:  You turned the unit off and back on while you were in the middle of a measurement sequence, after the cell was exposed to radon. The CT007-R should be turned on at the beginning of a measurement sequence and left on until all measurements for the day are complete. If it is not being used, leave it running in a low radon area. As you measure radon, radon decay products accumulate in the detector. These will contribute to the counts and can not be flushed out. Our algorithm tries to account for these in the calculation. Turning the unit off and on, with radon decay products in the cell confuses the calculation.

Solution:  The radon decay products will decay away in a couple of hours after the radon has been flushed out and you can resume your measurement. You can also connect to the Radon Sniffer app and turn off the “Smart” calculation switch. In that mode, the radon concentration values displayed on the app don’t try to compensate for radon decay products. There is no complicated algorithm that can get confused.

This issue can be avoided by not turning off the CT007-R before all measurements are completed.

3) Cause:  The ‘Smart’ algorithm got confused for another reason. This can happen if it registers many spurious counts (for example the black curly hose is detached from the CT007-R and light gets into the unit causing spurious counts). Now, the CT007-R will think there are radon decay products in the cell when there aren’t any.

Solution:  In this case, turn the unit off and back on to reset the algorithm. If there actually are a lot of radon decay products in the cell, this will not solve the problem. See 2) above.

4) Cause:  You exposed the unit to high radon concentrations for a long time and are now trying to measure low radon concentrations. When the CT007-R is exposed to high radon concentrations for a long time, many radon decay products accumulate inside. These contribute to the counts detected. Our ‘Smart’ algorithm accounts for the radon decay products and subtracts their contribution. However, this process is not perfect.

Solution:  Try to measure low radon concentrations first (i.e. living quarters in a house), before you start your diagnostics, where you could measure higher levels (e.g. inside a crawl space, block wall or below a slab). Use the ‘Short’ (15 second) display in high concentrations and only measure for long enough to get a good reading. Leave the sniffer running in low concentrations between measurements. The short lived radon decay products have half lives around 30 minutes and leaving the unit running in clean air for 30 min to an hour will get rid of a good portion of the radon progeny.

We have found that there are issues when connecting to CT007-R detectors using some phones running Android 7. This seems to be caused by an incompatibility between the way Android 7 handles Bluetooth versions and our firmware’s Bluetooth stack, which creates issues during service discovery. The latest release of the Radon Sniffer App (4.4.1) aims to address this issue. To get the full benefit of this update, your CT007-R detector’s firmware should be updated. The procedure to do so is as follows.

If possible, use an Android phone not running Android 7 to perform the firmware update. Android versions 4.3, 5, 6, and 8+ should all work better. If that’s not possible, an Android 7 phone can perform the update as well, but it may take several connection attempts before a successful connection is made.

1. Install the latest release of Radon Sniffer App (4.4.1).
2. Power on the CT007 detector and start Radon Sniffer App.
3. From the main menu (top left icon, or drag in from left of screen), go to ‘Settings’ under ‘External’.
4. When prompted for a password, enter the default ‘1234’.
5. Scroll down to the ‘Automatic Firmware Updates’ setting, and enable it. (Second last setting in the list.)
6. Make sure that the ‘Clear Bluetooth Cache’ setting is DISABLED. (That is the default setting, unless you previously changed it.)
7. Go to ‘External Detector’, and connect to your detector. As noted above, this may take several connection attempts before successfully connecting.
8. Once connected, the firmware update should start automatically.
9. Let the update finish and you will be automatically connected once it is done.

Note that if for any reason the update fails or is interrupted, it can be restarted and resumed as many times as necessary, with no risk of permanently bricking your detector. Even if you need to resume later from another phone. All you will need to do is to enter the serial number from your label.

Once the firmware is updated, connections to Android 7 devices should go better. Once the CT007-R detector has been connected to a particular phone, the connection parameters are cached and subsequent connections are much quicker.

After your Firmware is updated, you may want to disable the ‘Automatic Firmware Updates’ setting again. This also speeds up connection and it prevents GammaGuard from starting Firmware updates at inopportune times.

All our detectors use BotSpine as their firmware platform. During the firmware update process, lines of code are erased, then re-programmed over the air via Bluetooth. If the process gets interrupted due to a bad Bluetooth connection or other reasons, the incomplete firmware will cause the detector to not function properly.

To fix this, you will need to reconnect your detector to the Radon Sniffer App, and complete the firmware update. When connecting this time, the app may not recognise the detector as “CT-R-XX” in the scan list, due to the incomplete firmware. This doesn’t mean the detector is not advertising though. Instead it may appear as “BASIC#XX” or “BOTSP#XX”, which is the name of the firmware platform, then the last two characters of its MAC address. Click and connect to the detector named “BASIC#XX” or “BOTSP#XX” in the scan list. A pop-up window may ask you to select detector number. Type in the number based on the sticker on top of your detector. After this, the firmware update will start. This will take a few minutes to complete. Once the update is completed and successful, your detector will be automatically connected to the app.

If you continue to experience issues, try performing the update using another phone. Some Android phones have inherently unreliable Bluetooth connections, which can make updating difficult or impossible. Note though, that permanently bricking the detector during an update should not be possible, as it can always be attempted again on another phone.

This may happen on Android phones after many connections. When you disconnect your detector, it seems to be disconnected from Radon Sniffer App, but the phone hasn’t properly closed the connection. This leaves the detector in a connected state and not advertising.

If you encounter this situation, try to restart your phone. After a restart, the phone’s Bluetooth should resume working properly, and the problem should be fixed.

Not advertising (appearing in scan list) can also be fixed by turning the detector off and on again. It is still a good idea to restart your phone though, as its Bluetooth not working properly is generally the cause of this state

This may happen when the phone has cached incorrect Bluetooth credentials for the detector, possibly during a firmware update or a failed connection. If this happens, check the “clear Bluetooth Cache” option in the external detector settings. After a successful connection, the proper Bluetooth credentials should be stored. This setting can then be disabled again, as it may unnecessarily increase Bluetooth connection times.