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FAQs
Tech Notes |
FAQs - HardwareWho should upgrade to the Optibit interface? Is it really necessary to match the impedance of the electrodes to the TDT headstage? Question: Who should upgrade to the Optibit interface? Answer: TDT’s new Optibit (Optical Gigabit) PC interface consists of a PCI card (PO5) that fits into the PC and one or more Optibit-to-zBUS interface modules (FO5) that fit into zBUS racks. Users considering an Optibit upgrade should answer the following questions:
Users that will see the most improvement from an Optibit upgrade are those with RXn systems. RXn users that upgrade will see increased throughput (up to 8x faster than the original gigabit interface) and reduced susceptibility to electromagnetic fields in noisy environments. RP2.1 or RA16 users may also consider the upgrade if their systems are suffering from excessive noise or signal dropout. However, if these issues are not present, the performance increases provided by the Optibit interface with the RP2.1 or RA16 modules may not outweigh the downtime incurred by the interface upgrade. Question: I need to re-program my RXn microcode but can not erase it in the RPProg, Device Programmer. How do I proceed? Answer: The RXn devices are updated using the System 3 Device Programmer, similarly to other processors. However, the devices are erased differently. To update the RXn, follow the steps below.
Question: I am using the Medusa BioAmp and an RA16LI headstage and have grounded my unused electrodes to earth ground on a third party power supply. Yet, all of the unused channels are clipped. Why can't I get a good recording? Answer: The Medusa bioamp is electrically isolated, that is, it floats with no common/chassis/earth GND. This significantly decreases the noise from external devices like lights or electrical equipment. Connecting the electrodes to true or earth GND offsets the signal relative to the floating GND so that the signal clips. For the RA16LI, we recommend that unused pins be left floating (no input). If necessary you can tie them together and then tie them to the RA16LI GND pin. For high impedance headstages we recommend that you tie all unused electrode inputs to the headstage GND pin (do not let them float). Question: Is it really necessary to match the impedance of the electrodes to the TDT headstage? Answer: It is true that the impedance of the electrode should always be much less than the impedance of the headstage in order to have a good signal-to-noise ratio (SNR). However, the TDT low and high impedance headstages both have very high input impedances that are set specifically to record a high SNR only with an electrode whose impedance is in the specified range for that particular headstage. See the technical specifications page for your headstage to find out the acceptable impedance range. Question: Why do I only see signals from channels 1-4 and 17-20 even if I am acquiring data from 32 channels using 2 preamplifiers? Answer: By default, the TDT preamplifier is set to acquire from 4 channels. To operate the preamplifier in 16-channel mode, one needs to connect pins 17 and 18 together. Note: this connection is automatically made when connecting the preamplifier to a TDT 16-channel headstage. Question: Why am I having problems connecting to or passing a transfer test with my TDT rack when using the USB interface? Answer: There are two very common problems when using the USB interface. The first involves a mismatch between the USB version on the PC and the version on the TDT rack. When a TDT rack is using USB2.0 modules, the PC must also have USB2.0. The opposite setup (USB2.0 on the PC and USB1.1 on the TDT rack) should be compatible. Also, racks will not work together if there is some combination of USB1.1 and USB2.0 modules on the TDT racks. If you are not sure what USB ports are on your PC then you can 1) check the PC manual or 2) assume that it is probably 2.0 if the PC was purchased new within the last 3 years.
The other common problem with the USB interface concerns installing the hardware. When first connecting the rack to a PC or even to a new USB port on the PC, a windows message will open saying that the PC has found new hardware. If the TDT Drivers are installed, and ONLY if they are installed, then it is OK to search for the appropriate drivers (usually answer: Yes, only this time). The computer will prompt the user through several windows and then the installation will appear to be complete. A moment later, another Found New Hardware message will appear. It is absolutely necessary to install the hardware as many times as this windows message appears. It may be necessary to install the hardware many different times, depending on the specific hardware setup. |
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