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Tech Talk
Hardware News - updates and anomalies
Tips and Tricks - this issue, tips for RPvds and the RP2.1
FAQs - this issue, time slices
News Flash
Customer Support News
This issue's customer support news includes important information about technical support follow-ups, introduces our newest addition to the technical support team, and provides the low down on System IDs.
An Important Note on Technical Support Follow-ups
April, your Customer Support Advocate, works with our support staff to ensure that all technical issues are resolved in a timely manner. If you request technical assistance April will follow up by e-mail or phone to ensure that your technical issue was resolved to your satisfaction. If you prefer not to receive follow up contacts let us know by phone or e-mail (support@tdt.com).
Our goal is to help you use your TDT system to its fullest functionality.
What are System IDs?
As of February 1, 2003, System ID numbers are assigned to each new system shipped. System ID numbers will help us to diagnose problems faster and allow us to provide better customer support. A System ID sticker is placed on the back of each device caddie in the system, and for your convenience, on the front of the System 3 binder.
New Support Staff
In our ongoing efforts to provide the best possible customer support, we've added a new application and hardware support team member. Agustin (BSEE, MSEE) comes to us after several years in DSP engineering in the telecommunications industry.
TDT Goes Mobile 
Experiment anywhere your laptop can take you!
RMx Real-time Mobile Processors Now Available
Our new line of portable processors are self-contained versions of our real-time processors. Powered from the USB port, their power requirements decrease a typical laptop’s running time by only five percent. By combining a signal processor, a power supply, and a computer interface in one small form factor, the mobile processors give you the power of our real-time processors in a portable device.
The RM2 Mobile Processor is an all-in-one system for data acquisition and stimulus presentation. With the RM2’s digital and analog input and output capabilities, you’ll have all the options you need for a wide variety of experimental protocols. Fiber optic connectors also provide a direct connection to our Medusa amplifier and headstage systems. Acquire evoked potentials or explore neurophysiology right on your laptop with the power of TDT’s new RM2.
The RM1 Mini Processor is a low cost version of the mobile processor and is ideal for psychoacoustics and stimulus generation applications.
New System 3 Products
Check out our hot new products for data acquisition and protocol testing.
Experiment Test Module
The ETM1 can be used to feed a simulated physiological signal to the Medusa system, allowing the experimental setup to be tested without using a subject. The ETM1 can be used with either the chronic (RA16CH) or acute (RA16AC) Medusa headstages.
16-Channel Low-Impedance Headstage
This new headstage (RA16LI) for our Medusa Amplifier System is ideal for high-channel count, low-impedance applications like slow wave potentials and EEGs.
Loggerhead Data Acquisition
The Loggerhead (RA8GA) is a new general purpose data acquisition device for use with the RA16 Medusa base station. This eight-channel device allows for variable input voltage ranges from .1V to 10V.
Coming Soon!
OpenExplorer - a powerful data mining tool for the OpenEx software suite. Flexible plotting features allow you to explore the relationship between recorded data, stimulus parameters, and other defined events.
AF15k - a passive analog filter for Medusa systems. With a 15 kHz corner frequency, the AF15 removes large artifacts associated with devices such as eye coils before the Medusa digitizes the signal.
Tech Talk
Hardware News - updates and anomalies
We've recently made several engineering changes to improve the performance of select System 3 hardware modules. If any of the issues listed below affect your system, contact April, our customer support advocate, at (386)462-9622 to request further information or to request an upgrade and receive a return to manufacturer authorization (RMA).
RA16PA and RA4PA, Serial numbers < 3000
Some RA16PAs and RA4PAs generated a 3 kHz noise that masked neural activity.
Update: The voltage regulation on the preamplifiers has been modified to provide better control of voltage variation. The preamplifier has also been modified so that low battery voltage is indicated earlier. This 3 kHz noise artifact is not generated on all headstages with all electrodes. We recommend updating to the new preamplifiers only if your system generates this noise.
Multiple Devices
RA4PA and RA16PA,< 5000
RA8GA, EBOX, and BBOX,< 2000
Some batteries failed to charge or took an inordinately long time to charge after having been completely discharged. This problem is only likely to occur when the battery is allowed to fall to below 10% charge.
Update: All battery-operated devices that might have been affected by this problem have been upgraded to prevent the problem.
RA16AC, Serial numbers < 3000
The wire for the differential was sometimes severed while disengaging electrodes from the headstage. See the tech note #70 on our Website for symptoms.
Update: The differential wire has now been reinforced to reduce the instance of damage when removing electrodes.
FI5, Serial numbers < 3000
When using the Gigabit interface, communication problems sometimes occurred when setting attenuation of a PA5 mounted in the right-hand slot of the zBus device caddie.
Update: The FI5 chip has been upgraded. See the tech note #71 on our Website for a description of symptoms and information on device placement to avoid this problem. An FI5 chip upgrade is also available.
PS20, Serial numbers < 4000
Intermittent failure of hardware devices (especially if a particular rack of hardware is frequently losing communication) may be caused by power supply problems.
Update: We modified the design of our System 3 power supplies to resolve these issues last fall. If you experience the symptoms described above, please call TDT for technical assistance. We will make a quick determination as to whether the power supply is the problem.
Tips and Tricks - this issue, tips for RPvds and the RP2.1
This article includes some tips and tricks for dealing with common issues or anomalies. In this issue we focus on RPvds and the RP2.1. You’ll find more helpful news, anomalies, and tips in the Tech Notes section of our Website.
RP2.1 Tips and Tricks
Increased signal noise at lower sample rates.
At low sample rates (e.g. 6kHz, viewed in an oscilloscope) users may see increased signal noise due to increased noise at frequencies above the nyquist. Most of the noise is above the audible range of humans (>20kHz) and will not affect the signal quality in many cases. However, you can eliminate the noise by sampling at a higher rate or by filtering the signal after it is sent from the RPx device. If the circuit will not run at a higher sample rate you can place components in time slices to increase circuit efficiency and allow a higher sample rate. Note: If a signal is acquired on another device, the acquired signal may have aliasing artifacts associated with the acquisition system.
Channel one delay at 200 kHz.
When running a 200 kHz sample rate, analog input channel two is always delayed by one sample relative to analog input channel one. There is no delay at lower sample rates. Compensate for the delay by using a delay component on RPvds or by shifting the data by one sample.
RPvds Tips and Tricks
Error loading component specification file.
When double-clicking on an .rpd file to open it, RPvds might give the error "Error loading Component specification file: CmpSpec.txt". Instead of double-clicking the file, run RPvds first and then open the .rpd file from within the program.
PulseTrain2 - changing the nPulse value.
When the nPulse of a Pulse Train2 component is set to a lower value than it previously had, the component will pulse forever, because its internal counter keeps counting up from the original value. Set the Enable line of the Pulse Train2 component to 0 before changing nPulse, so that pulsing will be disabled. Trigger the Reset line of the component to reset the internal counter to zero before re-enabling pulsing.
FAQs - this issue, time slices
This article includes just a sample of the information you’ll find in the Frequently Asked Questions section of our Website. Please see the Support page on the TDT Website for links to more FAQs on installation issues, OpenEx, RPvds, ActiveX, SigGenRP, and BioSigRP.
Question: What are time slices and how should I use them?
Answer: Circuit components are executed on the real-time processors on each tick of the sample clock. Time slices allow users to execute a specific component or set of components less frequently then once a sample tick. For example, if the number of time slices is set to 10 and a component, such as a SerStore, runs in time slice 1, (Time Slice = 0 means that it runs in each time slice. Time Slice = -1 means it loads at run time.) data will only be stored to the buffer every tenth tick of the sample clock. If the number was 100 then data would be stored once every 100 ticks. So, one function of a time slices is to reduce the amount data stored to a buffer. If the data rate required is 100 Hz you can use time slices to reduce the number of points to that data rate.
However, you have to be careful using time slices. They should not be used with the DAC inputs, ADC outputs, or filters (you can use them with filter coefficients). In addition, component parameters that take inputs that generate a logical high for a short duration, such as software triggers (TrgIn) may fail to respond to the event. Make sure that the input produces a logical high that equals the number of time slices.
Another function of time slices is to decrease the cycle usage of a system. Components that run in a time slice only use DSP processing power during that time slice. For example, filter coefficients use a large amount of processing power. If several coefficient generators are running at once the cycle usage might exceed 100%. To avoid this you can have each of the coefficient generators running in a separate time slice. This may decrease cycle usage enough that you can run more complex circuits. However, you should always test the circuit to ensure that the cycle usage does not exceed 100% in any time slice.
Question: Can I have multiple OpenScope and OpenController applications running at the same time?
Answer: Yes, you can. Each Instance of OpenScope and OpenController runs as a client application of the TTank and OpenWorkbench server applications. All of your client applications can all be running at the same time. However, be careful when working with multiple instances of OpenController. Changing a parameter in one OpenController will affect that parameter in all other OpenControllers. For that reason, we recommend only using multiple OpenControllers if they access different sets of parameters. Multiple OpenScope instances should not have any problems, because they are used for data visualizations only.
The Master Mode control in OpenController can be used to start and stop the experiment. To avoid confusion, we recommend only using a Master Mode control in one of the OpenController instances.
News Flash: TDT Blues Bash a big hit! TDT Blues Bash a big hit!
Chris Thomas King
live at the ARO TDT Blues Bash!
With over 400 in attendance, a great new venue, and a live performance from Chris Thomas King, this year's annual ARO bash was a big success. We always enjoy putting together this customer appreciation event and we are glad so many of you could join us this year.
Copyright 2006 Tucker-Davis Technologies, Inc. All Rights Reserved.