TY - JOUR

T1 - An improved instantaneous frequency meter for use with a multi-trace CRO

T2 - re-examination of the principles involved

AU - Obara, S.

AU - Nagai, T.

PY - 1983/1

Y1 - 1983/1

N2 - The instantaneous frequency display of single unit discharges provides a useful measure of neuronal activities. Such a device must produce voltage outputs proportional to the reciprocal of each inter-spike interval by on-line computation of the hyperbola of V = a/t. Segment approximation of the required hyperbola can be made by a series of exponential functions which increase in time constants by a factor of m. Numerical analysis of a normalized function indicates possible error maxima of 3.4, 2.4 and 1.1% for m of 2, 1.8 and 1.5, respectively. This prediction is fully confirmed by the actual performance where m of 1.5 is adopted. The test circuit combines only readily available ICs and other components, to give a linear F-V conversion over a dynamic range of 4-600 Hz with error maxima of approximately 1%. The outputs are square pulses of approximately 1.5 ms in duration through the use of a flexible sample-hold circuit. Compared with that of earlier models, this display mode gives better photographic records with the base-line in simultaneous multi-trace display. Simple and systematic methods are described for designing a circuit to one's own specifications, and also for compensating for component variations.

AB - The instantaneous frequency display of single unit discharges provides a useful measure of neuronal activities. Such a device must produce voltage outputs proportional to the reciprocal of each inter-spike interval by on-line computation of the hyperbola of V = a/t. Segment approximation of the required hyperbola can be made by a series of exponential functions which increase in time constants by a factor of m. Numerical analysis of a normalized function indicates possible error maxima of 3.4, 2.4 and 1.1% for m of 2, 1.8 and 1.5, respectively. This prediction is fully confirmed by the actual performance where m of 1.5 is adopted. The test circuit combines only readily available ICs and other components, to give a linear F-V conversion over a dynamic range of 4-600 Hz with error maxima of approximately 1%. The outputs are square pulses of approximately 1.5 ms in duration through the use of a flexible sample-hold circuit. Compared with that of earlier models, this display mode gives better photographic records with the base-line in simultaneous multi-trace display. Simple and systematic methods are described for designing a circuit to one's own specifications, and also for compensating for component variations.

KW - instantaneous frequency

KW - nerve impulse

KW - reciprocal time-interval

KW - sample-hold

KW - segment approximation

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U2 - 10.1016/0165-0270(83)90022-5

DO - 10.1016/0165-0270(83)90022-5

M3 - Article

C2 - 6834889

AN - SCOPUS:0020695597

SN - 0165-0270

VL - 7

SP - 89

EP - 98

JO - Journal of Neuroscience Methods

JF - Journal of Neuroscience Methods

IS - 1

ER -