Frequently Asked Questions

1. How to program the logger

   From time to time we issue new versions for the firmware. Consequently, you will be able to reprogram the logger using the file that we will be able to send you. Make sure the logger is turned off and attach it to the PC via the download cradle. Now press the ON button on the logger repeatedly in quick succession (at least once a second). After about 10 pushes, it will come on in programming mode, indicated by the display glowing on and off. Go to the PowerLine software, and select Tools->Options->External tools->Reprogram Logger...  Select the correct serial port, select the file that you have sent you and select BURN.  After it has finished (30 seconds or so), turn off the logger in the usual way and it should be reprogrammed. 

2. What cameras are compatible with Peach video sync?

   PowerLine video synchronisation requires a Sony camera with the following features:

   • miniDV tape
   • LANC port
   • DV port (otherwise known as Firewire & IEEE1394)

   There are no longer any consumer-grade models available from new, but cameras can be readily purchased from eBay.

   The following Sonys will work: DCR-HC14, 15, 17, 19, 21, 22, 30, 32, 33, 39, 40, 42, 43, 85, 94, 96.

   The following will not: DCR-HC23, 24, 35, 36, 44, 46.

   There are many others that will work (e.g. from the Sony DCR-TRV range) - user manuals are generally available on Sony technical support websites: search for the three required features to check for compatibility & if in doubt, ask us.

   The following cameras are HD (high definition) units that ought to work with the system when running in SD mode (standard definition). This has not been tested: HDR-HC1, 3, 5, 7, 9.

   All camera models have an "E" suffix (e.g. DCR-HC40E) when configured for European PAL format

3. How do we calculate power?

   The power calculation is based on the integral of handle speed multiplied by force on the handle. Both terms are reduced to their components in the X-direction (i.e. the handle speed is produced by multiplying inboard, angular velocity and cosine(angle)), and the force on the handle is estimated by the product of oarlock_force and the quotient of outboard and oar-length (i.e. using the geometry entered into the logger). Note that obviously the oarlock force is already resolved to the X direction. Handle speed is taken simply as the difference between adjacent angle measurements at 50Hz. The integral is only aggregated when handle speed is positive, and the work done is normalised to a power value using the duration of each stroke.

   The start of a stroke for these purposes is what we call "drive start" - i.e. the moment that the force value goes above the threshold set in the logger. This tends to show less variability in timing than any other feature of the stroke (e.g. crossing of zero degrees on the recovery), so whilst it happens a little way into the drive, what power it loses from "its" stroke it tends to pick up from the start of the next stroke. The fairly crude calculation of handle velocity benefits from the same notion - i.e. sample jitter in adjacent samples complement each other and only start to cause inaccuracy in the integral where the force is changing rapidly. Whilst it would be possible to pick holes in this, or in fact any calculation of rower power, we have modelled quite a lot of data through spreadsheets and this seemed to provide fairly consistent results. Furthermore, it needs to be remembered that we have designed the system to provide real-time feedback within the boat - i.e. there are limitiations on the processing power and the type of algorithm that can be employed (i.e. forward-looking filters are a bit tricky!).

4. How do we create the chain between junction boxes and which sockets should we use?

   Remeber you will need as many junction boxes as seats in your boat, so for example eight junction boxes in an 8+. The first junction box in the chain, the one at the stroke seat, will have a cable coming out from the socket marked "STERN" towards the socket marked "BOW" in the junction box in position 7. Now repeat the process again. Get another cable and connect the socket market as "STERN" in position 7 to the socket marked as "BOW" in the junction box in position 6. So the direction to remember is: from "STERN" to "BOW". The same should be done in any sculling boat.

   Now that the chain is created, you will be able to install the rest of the sensors. The oarlocks will be connected to the corresponding side sockets. So for example, if the stroke seat is rigged as portside, we will connect the cable coming from the oarlock in position 8 to the socket marked "PORT" in the first junction box. The rest of the sensors can be connected to any of the free sockets. So normally, you will have the logger and the boat motion sensors attached to the first junction box. See the pictures below.

   

   Sweep junction box chain

   

   Scull junction box chain

Are you looking for any advice on how to spot the cause of specific problems with the sensors and software? Click here.