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At least 163 records · Page 9Linked to original sources

PubMed1985

Polysomnographic telemetry using Telediagnostic and Oxford Medilog 9000 systems.

Sleep was recorded in 24 normal adult sleepers (21-42 years of age) for 4 consecutive nights (2 nights in the laboratory and 2 nights in the home environment) using one of two commercially available telemetry systems, either the Telediagnostic or the Oxford Medilog 9000. Modifications to each system were necessary to approximate standard laboratory techniques for polysomnography. With comparability in recording techniques between systems, there were no qualitative or quantitative differences in standard electroencephalogram sleep parameters recorded in either the home or laboratory environment.

Adult↗

PubMed2001

Estimation of psychophysical levels using the electrically evoked compound action potential measured with the neural response telemetry capabilities of Cochlear Corporation's CI24M device.

OBJECTIVE: The goal of this study was to estimate psychophysical levels using the electrically evoked compound action potential (EAP), measured with the Neural Response Telemetry capabilities of Cochlear Corporation's Nucleus CI24M cochlear implant system. DESIGN: Twelve postlingually deafened adults with at least 3 mo of implant experience with the CI24M were subjects in this study. EAP growth functions were successfully quantified on each active electrode of every subject. Correlation and regression analyses were performed between EAP measures and cochlear implant fitting psychophysics. Other information including performance, etiology and duration of hearing loss, and individual electrode impedance was considered. RESULTS: EAP thresholds were found to be highly correlated with psychophysical thresholds. The rate of EAP growth with increasing stimulation levels was also found to be correlated with the dynamic range of loudness limits and psychophysical thresholds in some subjects. No relationship was evident between EAP measures and speech perception tests. CONCLUSIONS: Information from EAP growth function measurements may be used to estimate psychophysical information used in cochlear implant fitting but not to predict performance with the device.

Adult↗

PubMed2000

EEG telemetry with closely spaced electrodes in frontal lobe epilepsy.

The use of additional electrodes (other than standard 10-20 electrodes) has proved to be extremely useful in the investigation of patients with temporal lobe epilepsy. The development of 32- and 64-channel EEG machines, along with the reformatting capabilities of digital EEG has greatly increased the possibilities in the number of electrodes and recording montages. The authors wanted to determine whether the use of closely spaced electrodes designed to increase the coverage of frontocentral regions is of benefit in the investigation of patients with frontocentral epilepsy. Patients investigated for frontocentral epilepsy underwent EEG telemetry with closely spaced electrodes based on the 10-10 nomenclature. Twenty-three patients were studied. An additional 30 minutes was required by technicians to create the montage. Unilateral frontal or frontocentral epileptic abnormalities were observed in 10 patients, independent bifrontal in 5 patients, synchronous bifrontal in 4 patients, and no EEG changes in 4 patients. In no patient did the addition of closely spaced electrodes lead to a change in the classification of the EEG. Closely spaced electrodes did not reveal focal abnormalities, which were not already apparent with 10-20 electrodes, nor did they demonstrate evidence of laterality in bilaterally synchronous discharges.

Electrodes↗

PubMed2000

A telemetry system for the study of spontaneous cardiac arrhythmias.

The characteristics of spontaneous cardiac arrhythmias leading to sudden cardiac death are largely unknown. To study arrhythmias in animal models, an eight-channel implantable radio telemetry system has been developed to record continuously cardiac electrograms over a period of weeks to months, with maintenance restricted to changing batteries. The inputs are connected in a unipolar manner. Each channel has a gain of fifty and is AC coupled, band limited to 0.07-260 Hz. The signals are digitized with 12 bits resolution at 1000 samples/s. The amplifiers, analog-to-digital converter, and control logic are packaged in an implantable unit. An umbilical cable is passed through the skin to an external backpack unit for power and data transmission. A custom serial interface card, a PC/104 form factor 25-MHz 80386-based single-board computer with a PCMCIA wireless local area network (WLAN) card, and battery power supply make up the backpack. Data are read into the parallel port of the computer, buffered, then transmitted over the WLAN to the laboratory network where it can be analyzed and archived. Approximately 12 h of 14,000 bytes/s data can be collected with each set of batteries. The system is suitable for continuous monitoring of animal models of spontaneous arrhythmias and sudden cardiac death.

Animals↗

PubMed1997

Microcontroller-based underwater acoustic ECG telemetry system.

This paper presents a microcontroller-based underwater acoustic telemetry system for digital transmission of the electrocardiogram (ECG). The system is designed for the real time, through-water transmission of data representing any parameter, and it was used initially for transmitting in multiplexed format the heart rate, breathing rate and depth of a diver using self-contained underwater breathing apparatus (SCUBA). Here, it is used to monitor cardiovascular reflexes during diving and swimming. The programmable capability of the system provides an effective solution to the problem of transmitting data in the presence of multipath interference. An important feature of the paper is a comparative performance analysis of two encoding methods, Pulse Code Modulation (PCM) and Pulse Position Modulation (PPM).

Acoustics↗

PubMed1977

Urine marking and territoriality in Galago alleni (Waterhouse, 1837--Lorisoidea, Primates)--a field study by radio-telemetry.

A wild population of Galago alleni was controlled by trapping and followed by radio-tracking in the equatorial rainforest of Gaboon during three study periods of 3 months each in 1972, 73 and 75. The disposition of territories and the social organization are described, as well as their evolution through time. A new technique of radio telemetry permitted identification and localization of urine marking in wild galagos. Urine marking took place throughout the territory, with a fourfold increase in frequency in zones where there is a slight overlap with neighbouring territories (female--female or male--male). The function of urine washing (wetting of the soles of the feet with urine) is discussed in relation to five hypotheses proposed by different authors, and th data obtained in the field in Gaboon. We interpret this behaviour as a means of dispersal of urine marks (social signals) in a three-dimensional milieu where displacement by a combination of leaping and running creates numerous pathways.

Animals↗

PubMed1975

Electrical activity of grafted myometrium and its recording by radio-telemetry in unrestrained rabbits.

1. The electrical activity in myometrial grafts in fifty-one female rabbits with ear chambers fitted with pick-up electrodes has been monitored. An FM telemetry system has made long-term studies possible in the freely moving animal. 2. Two distinct patterns of electrical activity were observed either arising spontaneously or provoked by oxytocin. These were the 'long-duration burst' containing about 50-150 spikes, and the 'short-duration burst' containing 1-10 spikes. 3. The spike frequency within the long-duration bursts varied between 0-9 and 1-3 spikes sec-1 and was fairly constant during the first half of the burst. The frequency of the bursts in the long series of short-duration bursts was about 2-3 min-1. 4. When activity from grafts in two chambers in the same animal was monitored for long periods, spontaneous activity occurred at random throughout the day in each graft, indicating that the spontaneous activity was probably myogenic.

Animals↗

PubMed1985

An optical telemetry device to identify which dolphin produces a sound.

A small telemetry device, called a "vocalight," was designed for attachment to a dolphin's head using a suction cup. The vocalight lights up a variable number of light-emitting diodes depending upon the loudness of sounds received at a hydrophone within the suction cup. If vocalights matched for sensitivity are put on each dolphin within a captive group, observers can identify which dolphin produces a vocalization. Use of vocalights indicates that source levels of whistles from captive bottlenosed dolphins, Tursiops truncatus, range from approximately 125 to over 140 dB re: 1 microPa at 1 m.

Animals↗

PubMed1999

Presurgical evaluation of patients with epilepsy and normal MRI: role of scalp video-EEG telemetry.

When considering surgery for intractable partial seizures, even with high resolution MRI, some patients do not show structural abnormalities. The aim was to consider whether these patients were likely to proceed to surgical treatment after scalp video-EEG telemetry. All patients undergoing presurgical evaluation at the National Hospital for Neurology and Neurosurgery between 1995 and 1997 were reviewed and 40 were identified without definite MRI abnormalities. None of 40 disclosed a well localised epileptogenic zone concordant with other tests that would have allowed the patient to proceed directly to surgery. In five of the 40, evaluation led to a hypothesis that could be tested by intracranial studies; three proceeded to surgery. It is suggested that high quality MRI is performed first when surgical evaluation is undertaken and if negative the patient carefully counselled before proceeding with any investigations, as successful resective surgery is an unlikely outcome in such MRI negative cases.

Adolescent↗

PubMed1979

A multichannel telemetry system for recording cardiovascular neural signals.

A multichannel telemetry system was developed for use with chronically instrumented unrestrained cats. This system can simultaneously record efferent and afferent cardiovascular neural signals, bioelectrical noise arising near the electrode recording the neural signals, EEG, ECG, and a standard calibration signal. The miniature (18 cm3), lightweight (24 g), telemeter is a five-channel, time-multiplexed, pulse width modulation (PWM)/FM device employing a high frequency subcarrier (60 kHz) and two sampling frequencies (30 kHz and 6 kHz). The device is powered by two small 120 mA . h silver oxide cells; it has an indoor transmission range of 10 m and can operate for 48 h. One channel transmits a standard signal (a square wave of 100 Hz and 200 mVp-p) used to monitor and regulate the system's performance. When the variation in either the amplitude or frequency of the standard signal is greater than 10% of the control value, the transmitted bioelectrical signals are automatically discarded.

Animals↗

PubMed1980

Elimination of noise in telemetry systems by pulse-width discriminator.

A pulse-width-discriminator circuit (PWD) was developed and applied for noise reduction in an FM pulse-interval-ratio modulation telemetry system. The PWD was incorporated as an intermediary between the tuner and the demodulator. The application of the circuit as a noise filter is a result of its ability to distinguish between pulses of different durations and its ability to eliminate pulses whose durations are less than some predetermined value. Since spikes of radio-frequency interference (RFI) occurring at the tuner output were of significantly shorter duration than the encoding pulses, they were virtually eliminated by the PWD. This prevented false triggering of the demodulator and resulted in a noise-free final demodulated output signal. This system was tested during telemetered blood pressure measurements in an unrestrained dog and proved to be extremely effective in eliminating spurious noise caused by electromagnetic interference in the radio-frequency range.

Blood Pressure Determination↗

PubMed1980

An inexpensive pressure telemetry system.

An inexpensive telemetry system using transducers and recorders commonly available, i.e., Statham and Grass, is described. The direct-current signal of a Statham transducer is applied to a voltage-controlled oscillator, thereby frequency encoding the pressure sensed by the transducer. This encoded signal frequency modulates a Colpitts oscillator, which acts as a radio-frequency oscillator-transmitter in the 88- to 108-MHz band. This transmitter and transducer, along with a rechargeable NiCd battery pack (total wt 0.5 kg), are mounted in a canvas jacket and worn by a dog previously prepared with a chronic indwelling arterial catheter. With a fully charged battery pack, a signal can be transmitted up to 250 ft for 50 h. A frequency-modulation automotive receiver, powered by and interfaced with a Grass 7B recorder, receives the signal and drives a tachometer circuit that reconverts the audio-frequency signal to a voltage proportional to pressure. This voltage is then applied to the driver amplifier of the Grass to produce a charted record. This system introduces no distortion as seen by comparison of direct and telemetered signals and is drift free for intervals exceeding 24 h.

Animals↗

PubMed1983

Crystal-controlled telemetry system for long-term acquisition of physiological data.

A crystal-controlled telemetry system was developed for long-term high-reliability recording of blood pressure in unrestrained animals. The miniaturized transducer-transmitter system is powered by two lithium batteries that allow for more than 200 h of continuous recording of blood pressure before battery replacement. The total system has a flat frequency response of 0-25 Hz and a time stability of +/- 1 mmHg/day. Linearity is better than 0.5%. The high degree of dependability of the system permits us to perform continuous, unattended, around-the-clock recordings of pressure and heart rate in unrestrained animals. Very high dependability is achieved by the use of a novel piezoresistive blood pressure transducer and by the inherent stability of the crystal-controlled radio-frequency oscillator of the transmitter. The receiver is also crystal tuned to the measured transmitter frequency. This transmitter-receiver frequency locking ensures very reliable reception of the telemetered signal.

Animals↗

PubMed1975

A multichannel implantable telemetry system for flow, pressure, and ECG measurements.

The design of telemetry systems for chronic implantation within the body have progressed from simple single-channel devices to complex multichannel systems over the last 15 yr. Although chronic measurements of temperature, ECG, and pressure have been reported with good results, measurements such as dimension and blood flow have been difficult because of heavy power requirements. The design to be described is a multiplex system that will measure up to eight individual parameters simultaneously, including blood flow. Flow is measured using an electromagnetic transducer, and by special design, the normal high power requirements of the electromagnetic technique have been reduced to a few hundred milliwatts. The system is powered by two NiCad, rechargeable batteries which are periodically recharged through the intact skin by induction at 250 kHz to an implanted pickup coil. The presently constructed units have been configured to measure ECG, two pressures, temperature and ascending aortic flow.

Animals↗

PubMed1986

Miniaturized eight-channel telemetry system for long-term EEG registration of humans and laboratory animals.

According to the increasing importance of telemetric EEG registration, a miniaturized telemetry system for AC and DC transmission has been developed. The basic model has been constructed for the demands of experiments with small rodents. The transmitter is 19 X 13 X 5 mm in size and weighs 5 g including two 1.5 V batteries. The transmission of AC or DC potentials can be chosen for each channel separately. In the case of eight-channel transmission, the bandwidth ranges from 0.8 to 100 Hz, and in the case of using only one channel, signals up to a frequency of 17 kHz may be registered. Semimicroelectrodes with an electrode impedance of about 10 M omega, as well as conventional surface electrodes can be applied. In case of long-term EEG registration of humans the total amplification at V = 1,000 has to be enlarged by using an extension module. This module consists of an additional amplification stage, a modified HF oscillator to enlarge the omnidirectional transmission sphere and external batteries to increase the operation time of the transmitter. Small dimensions, light weight and multifunctionality plead for the attractivity of this construction according to various clinical and experimental demands.

Animals↗

PubMed2001

ECG data reduction method for medical telemetry systems.

In current medical practice, all transmitters used for monitoring an ECG send data continuously. If transmission could be limited to only the ECG data that requires the attention of a technician, the likelihood of interference and power consumption would be reduced considerably. In this paper, we propose a new ECG telemetry system. The transmitter has a simple ECG analyzer and it only transmits data when abnormal waveforms are detected. As part of this system, we propose a simple algorithm to detect an abnormal ECG. The algorithm is composed of a baseline drift canceller (utilizing a moving average calculation), a waveform detector (using a modified second order derivative) and an ECG analyzer. In order to test the effectiveness and feasibility of the algorithm, computer simulations (with a MIT-BIH ECG database) and experiments (with microprocessor-based hardware) were performed. The results of the simulations show that the detection performance and data compression performance of the algorithm are adequate. The results of the experiment show that the algorithm even performs adequately when used with microprocessor-based hardware that is of limited size or limited power consumption.

Algorithms↗

PubMed1985

Monitoring heart and breath sounds by telemetry.

A system for FM radiotelemetry of heart and breath sounds is described. Patients' heart and breath sounds are detected by oesophageal or precordial stethoscopes. The anaesthetist, carrying a portable radio receiver, is then free to move around theatre while listening to these sounds through headphones or an ear-piece. The FM telemetry system has also been used to assist patient monitoring in noisy environments such as ambulances.

Anesthesiology↗

PubMedDate not supplied

Indirect assessment of cardiovascular "demands" using telemetry on professional football players.

Aerobic training is not a major component of th conditioning programs of professional football players. We used telemetric ECG monitoring to examine the cardiovascular "demands" of practice and game situations in six athletes who were selected to affect a variety of positions and aerobic capacities. Heart rates commonly considered high enough for an aerobic conditioning effect were rarely attained during a practice sessions. Maximum oxygen consumption testing confirmed that professional football players do not receive a sufficient amount of aerobic conditioning during practice. Telemetrically monitored heart rate response is much greater in a game situation than that experienced during practice. Telemetry results support injury statistics by indicating that aerobic conditioning should have a significant role in the training program of the professional football player.

Adult↗