Patent No. 3886314 No hands voice instruction for EEG telemetering system
Patent No. 3886314 No hands voice instruction for EEG telemetering system (Pori, May 27, 1975)
Abstract
A no hands voice instruction system for specific use in an EEG telemetering system in which the EEG signal is FM modulated on several carrier frequencies and where a voice instruction signal is transmitted from the receiving end to a loudspeaker at the transmitting end of the system. The frequency modulated data information is prevented from being reproduced by the loudspeaker by means of a nulling arrangement in which the FM data channel signal is applied to both inverting and noninverting inputs of an operational amplifier one side of which is coupled to a telephone line pair over which the voice instructions are transmitted from the receiving end of the system. The loudspeaker is connected to the output of the operational amplifier.
Notes :
No
hands voice instruction for EEG telemetering system. Filed September 1973, granted
May 1975. States that the EEG data from 8 (or as many as used) different electrodes
could be modulated separately onto different carrier waves and sent through
a phone line to be recombined (or even left as is) in a computer for analysis.
Another form of remote neural monitoring. Also refers to inverting and non-inverting
signals nullifying each other.
BACKGROUND
OF THE INVENTION
The present invention is directed to a telemetering system for transmitting
multi-channel data over a voice quality transmission medium such as a telephone
line pair and more particularly to a system in which the receiving portion of
the system has the capability of giving "no hands" voice instruction to the
transmitting portion of the telemetering system.
In copending application Ser. No. 211,221 filed Dec. 23, 1971, in the name of
John R. Pori, entitled "Telemetering System for Multi-Channel Data" and now
U.S. Pat. 3,786,190 there is disclosed a telemetering system where EEG data
of eight channels is frequency modulated by eight different carrier frequencies
and transmitted over a telephone line pair. Such EEG or electroencephalographic
data is then studied at the remote or receiving end of the line pair by specialists
in that field and the evaluation is then communicated to the transmitting facility.
Such transmitting facility as explained in the above copending application will
generally be located in an outlying area where the patient resides but where
no specialist is resident.
In order to insure that the multi-channel data is being received and is of adequate
quality for interpretation and evaluation, it is necessary to communicate with
or give instructions to the resident doctor who is, for example, applying electrodes
from an EEG unit to the patient's head. It is, of course, most convenient to
use the same telephone line pair for this instruction as is being used for the
transmission of the EEG data.
In the past, telephone type hybrid systems have been used but they are costly,
are of excessive weight in the system which should be portable, and provide
for limited isolation of the multi-channel data being transmitted over the system.
Another technique has been proposed in Tygart U.S. Pat. No. 3,426,150 in which
a telephone hand set is used to couple the EEG device, for example, to the telephone
lines and where as stated by the patent the apparatus is designed to allow the
user to position his ear with respect to the telephone such that an incoming
conversation on the telephone may be heard. In order to block out the data being
transmitted a muting switch is provided which must be actuated. This shunts
the information to ground. Such a system as disclosed in the Tygart patent is
obviously inconvenient and cumbersome in use.
In yet another Tygart U.S. Pat. No. 3,426,151, the use of a band elimination
filter to filter out the data channel from the voice instruction channel is
suggested. This has the defect in reducing fidelity of sound and also providing
for poor isolation from the data channel. In addition, the '151 Tygart patent
is used for EKG information at a single carrier frequency whereas EEG information
requires multiple carriers as discussed in the Pori patent.
OBJECTS AND SUMMARY OF THE INVENTION
It is, therefore, a general object of the present invention to provide an improved
no hands voice instruction system for use in a telemetering system.
It is a more specific object of the invention to provide a system as above especially
useful for multi-channel data.
In accordance with the above objects there is provided a telemetering system
for transmitting multi-channel data over a transmission medium which is a single
voice quality communications channel. The multi-channel data frequency modulates
a unique carrier frequency for each data channel for providing a frequency modulated
signal for transmission over the communications channel. The system includes
receiving means coupled to the voice channel for demodulating the frequency
modulated signal and displaying such multi-channel data for interpretation.
Transmitter means couple the frequency modulated (FM) signal to the voice channel.
First amplifier means couple the FM signal to the voice channel and has a gain
for amplifying the signal to a predetermined level suitable for transmission
over the voice channel. Operational amplifier means are provided which have
an inverting input and a noninverting input. Voice instruction signals transmitted
from the receiving means over the voice channel are coupled to one of the inputs.
Second amplifier means couple the FM signal to the other input of the operational
amplifier means and has substantially the same gain as the first amplifier means
for matching the predetermined level. Loudspeaker means are coupled to the output
of the operational amplifier for receiving the voice instruction signals. The
inverting and noninverting inputs null out the FM signal.
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