| Date: | 2005-08-23 08:40:00 | |
| Sender: | Francis Pierron & Philip Gibbs <Philip Gibbs <pgib@nerc.ac.uk>> | |
| Subject: | [SLR-Mail] No. 1359: Herstmonceux Workshop Timer session | |
| Author: | Francis Pierron | |
| Content: | ******************************************************************************** SLR Electronic Mail 2005-08-23 08:40:00 UTC Message No. 1359 ******************************************************************************** Author: Francis Pierron & Philip Gibbs Subject: Herstmonceux Workshop Timer session Subject: Request for imput to Timer Session Subject: Request for imput to Timer Session Herstmonceux Workshop * Timers Session Chairs Francis Pierron & Philip Gibbs We would like to encourage as many stations as possible to do some tests using their timers and present their findings however incomplete at the workshop. There are 2 main areas where timing devices can introduce errors in the data. 1) Non-linearities over a short range. Eg the SR620 shows in the manual a non-linearity over 11ns (90Khz). This only adds jitter to the satellite observations but can produce and error in the calibration as you are measuring a constant range. 2) Non-linearities over the full SLR range (0-150ms). Test 1 If possible could you do checks against a movable calibration target. What we would like is for stations to take a calibration, move the target by some small amount (say 10cm) and then do another calibration. This should be repeated as often as is possible * even just 2 or 3 measures would be useful. If your timer is linear you should see a change in calibration equal to the movement of the target. For most of us the calibration range we measure (cables,optics and target distance) is a random timer range and it is important to verify that we get the same calibration value whatever total range we measure. Test 2 Could any stations with access to more than 1 timing device make simultaneous readings at a number of different ranges using all their timers. By splitting the signall to start/stop and taking readings you should get a series of readings which have a constant difference against range if your device is linear. We would also welcome presentations on any other investigations that have been carried out on linearity and accuracy of timing devices as well as any news on new timing devices. From: ”Philip Gibbs” ******************************************************************************** |