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RX8 Tech Notes

RX8 PCM ADC data inversion

TN0260

Product: RX8
Version: Serial numbers < 8000
Date Added: 2007-08-16

Issue

There is a data inversion issue with the PCM ADCs on the RX8. This ONLY affects the PCM ADC for the RX8.

Workaround

Place a ScaleAdd component with an SF of '-1' to invert the data to your circuit like the example shown below.

Solution

Contact TDT for an RMA to update the firmware on the RX8.

RX8 50/60Hz signal noise

TN0259

Product: RX8
Version: Serial numbers < 8000
Date Added: 2007-08-09

Issue

An impedance mismatch on the RX8 may allow 50/60 Hz noise to bleeding through onto signals acquired via the RX8's Sigma/Delta ADCs.

Solution

Please contact TDT and request an RMA for upgrade to address this problem.

Distortion or noise on RX8 PCM ADC inputs

TN0247

Product: RX8
Version: Serial Numbers < 7000
Date Added: 2007-03-22

Issue

Internal timing conflicts may cause distortion or noise in the form of spikes on the RX8 PCM ADC inputs.

Important

This problem only affects the PCM ADCs and NOT the Sigma Delta ADCs.

Solution

If you experience this problem please contact TDT for an upgrade.

RX8 analog I/O channel 24 is not available when operating the device at 100 kHz

TN0229

Product: RX8
Version: All
Date Added: 2006-10-31

Issue

Because of device timing constraints at higher sampling rates, only the first 23 channels of analog I/O are processed when operating the RX8 at 100 kHz.

For PCM DACs, channel 24 works at up to 94696 Hz sampling rate.

For SD DACs, channel 24 works at up to 78125 Hz sampling rate.

RPvdsEx does not properly block unsupported sample rates on the RX8

TN0228

Product: RX8
Version: All
Date Added: 2006-10-27

Issue

The RX8 allows sample rates up to 100KHz, however RPvdsEx may allow the user to enter arbitrary sampling rates above 100 kHz in the RX8 Device Setup.

Workaround

When entering arbitrary sampling rates in the RPvdsEx Device Setup, enter only sampling rates that are supported by the device, i.e. up to 100 kHz for the RX8.

Noise on RX8 PCM DACs

TN0225

Product: RX8
Version: Serial numbers < 6000
Date Added: 2006-10-27

Issue

Internal timing conflicts could cause noise in the form of spikes to appear at the output of the RX8's PCM DACs.

Solution

If you experience this problem contact TDT to request an upgrade.

Anomalous signal on an analog output of an RX device when the channel is not in use

TN0198

Product: RX5, RX6, RX7, RX8
Version: All
Date Added: 2005-10-06

Issue

The DAC outputs of the RXn processors will continue to generate a signal under the following conditions:

  • Input to the DAC channel is greater than zero immediately before switching the DacOut channel parameter.

  • Input to the DAC channel is greater than zero immediately before halting the processing chain.

  • Input to the DAC channel is greater than zero immediately before loading a new processing chain.

Workaround

Make sure that the inputs to all DAC channels are zero before doing any of the above. This can be done by gating the signal or setting the DAC output to zero before switching channels, halting the processing chain, or loading a new chain.

Note

The anomalous signal can be terminated by cycling power on the zBus rack holding the RXn processor.

Configuration Register for the RX8 device setup is not displayed

TN0165

Product: RX8
Version: TDT Drivers 58 and 57
Date Added: 2005-01-18

Issue

When the RX8 is selected in the RPvdsEx Device Setup (Set Hardware Parameters dialog box), the Device Configuration Registers used to configure the programmable I/O lines are not displayed.

Workaround

To configure the programmable I/O lines on the RX8, first select RX6 and configure the registers as desired, then select RX8. Your configuration will be applied to the RX8.

Solution

Update to latest version of TDT Drivers.