Record & Play

Record

Acoustics only

Multi-channel

This method is the same for both PC and Mac.

To check the levels of the channels, start the scope window by Record/Play->Scope Mode menu, which opens a screen with all the selected channels showing along with their signals. To change the settings for the hardware, open Record/Play Options to change settings as needed. Once you have all the proper settings, then close the scope view and do the actual recording. Upon saving the recorded file, all the proper settings, are stored along with the file and can no longer be changed. The Record/Play Options window can stay open throughout the recording process. 

The recording cannot be interrupted and will continue until the end of the requested recording time. You may want to save a copy of this file, File->Save a Copy As..., as a different name, hence preventing the save as message from appearing. This way you can record many subjects quickly.

You will notice a wide range of sample rates available for various channels. These sample rates are all based on the acoustics channel sample rate and will change accordingly. The filter rates are also change with the channel sample rate. The audio filter is a 10 pole and the rest of filters are, 8 pole ,all low pass butterworth. The filter frequency sets the corner frequency of the filter. They default to the about 40% of the sample rate maximum and can be lowered to a desire value. All these values are calculated according to the sample rate selected.

The acoustics channel (channel 0) is an AC coupled channel and the rest are all DC coupled. Therefore care must be taken when recording any DC varying data, as the reference value may or may not be the ground (zero). In general it is always some definite value. This reference value plays an important role in all the subsequent value measurement and calibration procedure. All the measured values are referred to the reference value. Therefore after each DC data acquisition, you MUST set a proper reference value for each data channel. You can do this either automatically for all channels at once by placing the marker on the proper location for the reference , then use Channels->Set Reference menu, or enter them manually in the Options->Display.

All the channels have +/- 2.5 volt input level with 10K input impedance. If you have the transducer interface connected to the channels 1-4 for two flows and two pressures, then outputs of the unit is matched to all the inputs. However, if you choose to input any other source to any of the channels, then make sure the signals are within the proper range.

The audio channel along with first 4 channels are all routed through front panel mini-din connector and mini jacks. The signals from the mini-din connector, is routed through the mini jacks. If any plug inserted into these jacks, it will interrupt the mini-din signal without shorting them out. For systems with more than 5 channels, the extra channels are available through the 15 pin VGA connector. These signals are all connected directly to the internal buffers and filters.

There are eight filters that control the channels in the following way:

Filter 0 1 2 3 4 5 6 7
channels acoustics channel#1 channel#2 channel#3 channel#4 channels#

5 & 6

 channels#

7-10

 channels#

11-15

 

Play

Playing is the same for both platforms. The play applies only to the acoustics channel (channel 0)

If the programs the presence of the external hardware, then you will have a choice to direct the output to the hardware or to the computer sound system. The external hardware will give the added advantage for a line output, in case you wish to output your acoustics data into a tape recorder.

The play menu will provide three ways of playing the audio.