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Add voltage conversion equations to Neuropixels DataFrame docs #367

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Add voltage conversion equations to Neuropixels DataFrame docs #367

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16 changes: 12 additions & 4 deletions OpenEphys.Onix1/NeuropixelsV1DataFrame.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -37,17 +37,25 @@ public NeuropixelsV1DataFrame(ulong[] clock, ulong[] hubClock, int[] frameCount,
/// Gets the spike-band data as a <see cref="Mat"/> object.
/// </summary>
/// <remarks>
/// Spike-band data has 384 rows (channels) with columns representing the samples acquired at 30 kHz. Each sample is a
/// 10-bit, offset binary value encoded as a <see cref="ushort"/>.
/// Spike-band data has 384 electrodes (rows) with columns representing the samples acquired at 30 kHz.
/// Each sample is a 10-bit, offset binary value encoded as a <see cref="ushort"/>. To convert to
/// microvolts, the following equation can be used:
/// <code>
/// V_electrode (uV) = 1171.875 uV / AP Gain × (ADC result – 512)
/// </code>
/// </remarks>
public Mat SpikeData { get; }

/// <summary>
/// Gets the LFP band data as a <see cref="Mat"/> object.
/// </summary>
/// <remarks>
/// LFP data has 32 rows (channels) with columns representing the samples acquired at 2.5 kHz. Each sample is a
/// 10-bit, offset binary value encoded as a <see cref="ushort"/>.
/// LFP-band data has 384 electrodes (rows) with columns representing the samples acquired at 2.5 kHz.
/// Each sample is a 10-bit, offset binary value encoded as a <see cref="ushort"/>. To convert to
/// microvolts, the following equation can be used:
/// <code>
/// V_electrode (uV) = 1171.875 uV / LFP Gain × (ADC result – 512)
/// </code>
/// </remarks>
public Mat LfpData { get; }
}
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8 changes: 8 additions & 0 deletions OpenEphys.Onix1/NeuropixelsV2eBetaDataFrame.cs
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Expand Up @@ -25,6 +25,14 @@ public NeuropixelsV2eBetaDataFrame(ulong[] clock, ulong[] hubClock, Mat amplifie
/// <summary>
/// Gets the amplifier data array.
/// </summary>
/// <remarks>
/// Wide band (0.5 Hz - 10 kHz) electophysiology data array. Each element is a amplified sample from
/// 384 electrodes (rows) acquired at 30 kHz (columns). Each sample is a 14-bit, offset binary value
/// encoded as a <see cref="ushort"/>. To convert to microvolts, the following equation can be used:
/// <code>
/// V_electrode (uV) = 0.91553 uV × (ADC result – 8192)
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The equation I've been using is 1/80/pow(2,14)*1e6 = 0.7629 uV

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That makes sense, not sure where I got my number from tbh.

/// </code>
/// </remarks>
public Mat AmplifierData { get; }

/// <summary>
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8 changes: 8 additions & 0 deletions OpenEphys.Onix1/NeuropixelsV2eDataFrame.cs
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Expand Up @@ -23,6 +23,14 @@ public NeuropixelsV2eDataFrame(ulong[] clock, ulong[] hubClock, Mat amplifierDat
/// <summary>
/// Gets the amplifier data array.
/// </summary>
/// <remarks>
/// Wide band (0.5 Hz - 10 kHz) electophysiology data array. Each element is a amplified sample from
/// 384 electrodes (rows) acquired at 30 kHz (columns). Each sample is a 12-bit, offset binary value
/// encoded as a <see cref="ushort"/>. To convert to microvolts, the following equation can be used:
/// <code>
/// V_electrode (uV) = 2.44141 uV × (ADC result – 2048)
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See above...

1/80/pow(2,12)*1e6 = 3.05176 uV

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Volts per bit should be exactly 4x higher than for the beta probes

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I get the 4x thing (14->12 bit) but I see this on the data sheet:

image

is it 80 or 100 for the public version?

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This on latest brochure as well

https://www.neuropixels.org/_files/ugd/328966_2b39661f072d405b8d284c3c73588bc6.pdf

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I was confused about that as well – but I confirmed that there is exactly a 4x difference by putting beta and commercial probes in the same saline bath

/// </code>
/// </remarks>
public Mat AmplifierData { get; }

internal static unsafe ushort GetProbeIndex(oni.Frame frame)
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