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iD2 Digital Headstage Interface

The iD2 is an interface to Intan-based digital headstages. It has two input connectors that can read up to 128 channels each, for a total of 256 channels. All raw data is streamed via USB 3 back to the computer running Synapse and recorded straight to disk. A compressed signal of all 256 channels is returned to Synapse for visualization. Up to 16 selectable channels of the raw data are also available on the DSP for real-time processing and visualization.

  • The iD2 includes impedance testing functionality for each headstage

  • Onboard LEDs provide live feedback of the headstage connection and activity

See the Hardware Manual for information on iD2 technical specifications.

Important

The iD2 USB Streaming capability is not compatible with the iPac and SynCon software.

iD2 Options

iD2 Interface

Recording Channels

Select the total Channel Count to return from the iD2. This is the sum of all headstages that are connected to the iD2 that you want to read.

There are selectable Sample Rate options of ~750 Hz, ~1.5 kHz, ~3 kHz, ~6 kHz, ~12 kHz, ~25 kHz, or system rate (maximum ~25 kHz). The lowest practical rate improves noise performance.

Enable Plot Decimated Data to return a highly compressed version of the raw signal to the processor and Synapse for visualization of all headstage channels. The plot decimated data consists of the max and min values of a short chunks of points. The rest of the chunk is thrown away. The data rate depends on the System rate and number of channels, but is usually ~300-1500 Hz. This is fine for monitoring the signal for activity and requires very low bandwidth, but is not useful for data analysis.

The plot decimated data can optionally be filtered on the iD2 itself. If the iD2 is running at ~6 kHz or above, you can enable a 100 Hz, 300 Hz, or 500 Hz filter on the device. At lower sampling rates, there is no filter available.

At runtime, you can use the Plot Decimated Filter cutoff frequency as a highpass, as a lowpass, or disable it. See Runtime Interface below.

Set a Channel Map to rearrange the channels on the iD2 before they are returned to the processor. The format of the CSV file for specifying the channel map is:

{Synapse Channel},{Headstage Channel}
{Synapse Channel},{Headstage Channel}

You do not have to map all the channels, and you can list the map in any order/

Focus Channels

Up to 16 user-selectable Focus Channels are returned to the processor and Synapse at the full data rate for real-time processing and visualization.

Optionally create Single Channel Outputs to link to other gizmos, depending on the number of focus channels you have.

Use the Plot / Save option to visualize and/or store the raw signal from the focus channels at runtime.

USB Streaming

The front panel of the iD2 has a separate USB3 connection back to the computer that is running Synapse. This connection is stream all channels at full bandwidth straight to disk without going through the processor interface bottleneck.

By default, the iD2 uses the Sample Rate defined in the Recording Channels section. You can select the data format and any scaling. If the Sample Rate is set to System, then the Integer-16 format (with Scaling set to 1e6) is preferred. If Sample Rate is lower than the RZ processor clock, you can get higher fidelity with the Float-32 data format.

Segment Files Every lets you split up the data files automatically at the specified interval. The new file will begin exactly one sample after the previous file. This is useful for long recordings where the user wants access to the raw data for parallel processing before the recording is over.

Run-time Monitor adds a runtime interface that warns you of data errors and USB connection issues. It shows the internal buffer status, data saved, and space remaining.

By default the data is stored in the same block folder as the rest of the recording. Use the Store Location option to save the iD2 data files to a different folder.

Impedance Checking

The Impedance Check option adds a run-time interface for enabling the impedance checking built into the Intan headstage.

Define the Low Target and High Target impedance thresholds for controlling the color of each channel LED in the runtime interface. This is used to intelligently control the impedance checking circuit on the headstage based on your target impedance.

Save to CSV logs impedance values into a CSV file stored within the block folder, whenever an impedance check runs.

Runtime Interface

iD2 Runtime Interface

Set the state of the plot decimated filter to lowpass (LFP), highpass (SU), or disabled (Off).

USB Streaming Status

The runtime interface shows the current status of the USB connection. Any errors will turn the LED red and display a message in this box.

The progress bar indicates how much of the iD2 buffer is full of data that hasn't been transferred yet. This will typically be at 0% during runtime, but may spike at the beginning of the recording when the storage files are being generated, or if there are any data transfer issues to the PC.

The runtime interface also shows how much data has been recorded from the iD2, and an estimate of the recording time available on the hard drive.

Note

See the iD2 section of the System 3 Manual for more information about Data Streamer operations.

Focus Channel Control

iD2 Focus Channel Interface

Use the table to create a custom column of channel numbers to include in the focus channel set. You can create multiple columns and double click the column header to choose the "Active" set of channels to return to the focus channel stream. Click the lock icon to lock the currently active column.

Impedance Checking

Click the Impedance button to switch the iD2 into impedance checking mode.

iD2 Impedance Check Interface

Users can select a Probe Frequency of 24 Hz, 48 Hz, 95 Hz, 191 Hz, 381 Hz, 763 Hz, 1526 Hz, or 3052 Hz for the impedance check. Take care that you do not choose a frequency that is beyond the Nyquist frequency (~½ the sampling rate defined during designtime).

The iD2 loops through the banks of channels and updates the impedance values for each channel, coloring the LED depending on its impedance relative to the high and low target impedances. The Group LEDs display the highest value for each set of 32 channels. Double-click on a Group LED to actively display that set of 32 channels.

Click the Save button to log the current impedance values to the CSV file.