Nortek Vector Comprehensive Manual

Also see for Vector: Quick start guide

Contents

Nortek Vector Comprehensive Manual Manual pdf 27 page image

Using a Velocimeter 27© 2018 Nortek AScapacity is crucial. We recommend starting new deployments with an empty memory.9. For stand alone systems, it is vital to remember to connect the dummy plug to protect theconnectors.2.1.4 Configuring a VectorThe Deployment Planning dialog contains all parameters required to specify the operation of theinstrument. The Deployment Planning frame on the right hand of the dialog displays performanceparameters that are automatically updated as you change the parameter settings.The deployment Planning dialog allows you to specify the instrument operation at two levels. Use theStandard tab to configure the system with default settings for various environments and mountingarrangements. Use the Advanced tab to fine tune the operation parameters. It is recommended touse the Help file that is available within the instrument software for a complete overview of each of thesetup parameters, what they mean and what effects tuning them has.For general recommendations for sampling in specific environments, check out these sections:Things to Consider, Applications and Common Configuration Scenarios.Sampling StrategiesA general rule when selecting an appropriate sampling strategy is to consider how often you needdata and what type of variations you want to resolve.Continuous sampling: the instrument is actively collecting data at all times until it is stopped.Burst sampling: the instrument will sample rapidly for a set period of time. A general rule to figureout the maximum sampling rate for a certain configuration is to consider what information you wantto resolve.Figure: Sam pling sequence w hen an instrum ent is configured for Burst sam pling, w ith 600 sec burstinterval, 300 sam ples at 1 HzSampling RateWhen it comes to sampling rate, the general recommendation is that you will need to sample atleast twice as fast as the signal of interest in order to unambiguously resolve it (i.e. the Nyquistsampling criteria). You will need to make a few estimates of what time scales and processes are ofinterest and select a sample rate appropriate for those. For autonomous deployments: You need tobalance memory and power limitations also.For example, when measuring waves, the sampling should be set up such that the wave record is“well sampled.” This generally means the burst is greater than 15 minutes in duration. This caneasily be achieved if the instrument is set to 1 Hz and 1024 samples, or 2 Hz and 2048 samples.This provides over 17 minutes of data and both examples are encouraged setups.Internal Sampling RateThe higher the velocity data output rate (for example by selecting 64 Hz in the configuration dialog)the less internal averaging is occurring. This is related to the ping rate. Here are some relevantterminology:Ping rate: How often the instrument transmits pings.Internal Sampling Rate: The internal sampling rate is fixed within each velocimeter according to itsacoustic frequency and velocity range. From a data quality perspective, the interesting parameteris the internal sample rateSampling Rate: Parameter set in the software. It sets the output rate of the data. It also sets thedate at which data are recorded internally or to disk.