EXAMPLE OF A DIGITAL ANALYZER: Stealth digital analyzer and sweep system
The SDA-5000 is used for HFC network testing and deployment of digital video, data, and traditional analog services. It is part of a system sweep solution.

Highlights:

- Qualifies the network for today's high-growth subscriber services.
- Reduces technician time for the most labor intensive maintenance and troubleshooting.
- Advanced QAM analysis for 64, 128, and 256 QAM (optional).
- Spectrum display from 5 to 1,000 MHz with cable modem analysis (Zero Span mode).
- Totally non-interfering sweep, specifically for 64, 128, and 256 QAM digital channels.

Applications:

- Non-interfering, continuously referenced sweep.
- Cable modem analysis using Zero Span mode.
- Full in-service, proof-of-performance analyzer.
- QAM View option provides complete analysis of digital TV and forward cable modem signals.
- Find ingress fast with Field View option. Cable technicians working in the field can see the reverse path at the headend.

Key Features:

- Forward and reverse sweep in one handheld instrument.
- QAM View includes BER, MER, and constellation.
- Equalizer stress and microreflections.
- QAM ingress (noise-under-carrier).
- New graphical test point compensation for easier setup.


Includes:
- Acterna Wavetek JDSU SDA-5000
-- Option: Forward Sweep
- Battery Pack
- AC Charger
- Power Cord
- Soft Case with Carrying Strap
- Manual on CD-ROM
- Getting Started Guide On CD-ROM

ANOTHER EXAMPLE: A digital analyzer for determining the liquidus temperature of metals and alloys, comprising

a converter for converting the actual temperature of metals and alloys to a digital pulse code, having an input, whereto there is applied a signal carrying information on the actual temperature of a metal or alloy being analyzed in the process of cooling, a first output for code pulses corresponding to a positive increment of temperature, and a second output for code pulses corresponding to a negative increment of temperature;

a clock pulse generator having an output;

a synchronization unit for distributing clock and code pulses in time, having

first, second and third inputs, a first output for synchronized code pulses corresponding to a positive increment of temperature, a second output for synchronized code pulses corresponding to a negative increment of temperature, and a third output for synchronized clock pulses;

a reversible counter for generating a parallel code of the actual temperature, having an add input, a subtract input, and an information output;

a discriminator of local temperature increments, having

first and second inputs, a first output whereto a signal is applied with a predetermined positive increment of temperature, and a second output whereto a signal is applied with a predetermined negative increment of temperature;

a first time interval discriminator for selecting time intervals during which the predetermined increment of temperature occurs, having

a count input, a first reset input, a second reset input, an intermediate output and an output;

a second time interval discriminator for selecting time intervals during which the predetermined increment of temperature occurs within a period of time exceeding said predetermined value, having

a count input, a first reset input, a second reset input, a disable input for blocking said second reset input, an intermediate output, and an output;

a register for storing the result of the analysis, having

an information input, a control input, and an information output;

an OR gate, having

a first input, a second input and an output;

a digital display unit for displaying the result of the analysis in a digital form, having

an information input, and a control input;

said first input of said synchronization unit, connected to said first output of said converter for converting the actual temperature of metals and alloys to a digital pulse code;

said second input of said synchronization unit, connected to said second output of said converter for converting the actual temperature of metals and alloys to a digital pulse code;

said third input of said synchronization unit, connected to said output of said clock pulse generator;

said first output of said synchronization unit, connected to said add input of said reversible counter and to said first input of said discriminator of local temperature increments;

said second output of said synchronization unit, connected to said subtract input of said reversible counter and to said second input of said discriminator of local temperature increments;

said third output of said synchronization unit, connected to said count input of said first time interval discriminator, and to said count input of said second time interval discriminator;

said first output of said discriminator of local temperature increments, connected to said first reset input of said first time interval discriminator and to said first reset input of said second time interval discriminator;

said second output of said discriminator of local temperature increments, connected to said second reset input of said first time interval discriminator and to said second reset input of said second time interval discriminator;

said intermediate output of said first time interval discriminator, connected to said disable input of said second time interval discriminator;

said output of said first time interval discriminator connected to said first input of said OR gate;

said output of said second time interval discriminator connected to said second input of said OR gate;

said intermediate output of said second time interval discriminator, connected to said control input of said register;

said information input of said register, connected to said information output of said reversible counter;

said information input of said digital display unit, connected to said information output of said register;

said output of said OR gate, connected to said control input of said digital display unit.

2. A digital analyzer as claimed in claim 1, wherein said second time interval discriminator comprises

a controlled time counter, having

a count input which is said count input of said second time interval discriminator, a first reset input which is said first reset input of said second time interval discriminator, a second reset input, an intermediate output which is said intermediate output of said second time interval discriminator, and an information output which is said output of said second time interval discriminator; a gate for blocking said second reset output of said controlled time counter, having a control, input, an input and an output;

a flip-flop for controlling blocking of said second reset input of said controlled time counter, having

a reset input which is said disable input of said second time interval discriminator, a set input and a set output;

said set input of said flip-flop, combined with said input of said gate and serving as said second reset input of said second time interval discriminator;

said set output of said flip-flop, connected to said control input of said gate;

said output of said gate, connected to said second reset input of said controlled time counter.

FIELD OF THE INVENTION

The present invention relates to digital measuring devices for checking parameters of molten metals and alloys and, in particular, to digital analyzers for determining the liquidus temperature of metals and alloys.

The invention can be employed in automatic systems for checking and controlling steel melting processes.

DESCRIPTION OF THE PRIOR ART

Known in the art is a digital device for automatic checking of the carbon content in metal with reference to thermal arrests of the cooling curve (cf. UK Pat. No. 1,477,564), comprising a converter for converting the actual temperature of metals and alloys to a digital pulse code, to whose input there is applied a signal carrying information on the actual temperature of metals and alloys in the process of their cooling, whereas at its outputs there are formed code pulses corresponding to positive and negative temperature increments. The device also includes a clock pulse generator. Through a synchronization unit for distributing code and clock pulses in time, outputs of said converter are connected to add and subtract inputs of a reversible counter, and to inputs of a discriminator of local temperature increments. The reversible counter produces a parallel actual temperature code. The discriminator of local temperature increments is adjusted so that at one of its outputs there is formed a pulse whenever a certain positive or negative value ε ₀ is set therein. The output of the generator is coupled via the synchronization unit to a count input of a time interval discriminator intended for selecting time intervals during which predetermined temperature increments ±ε ₀ occur. Reset inputs of the time interval discriminator are connected to outputs of the discriminator of local temperature. The time interval discriminator is designed so that at its output there is formed a signal only if the selected time interval exceeds a predetermined threshold τ ₀ . An output of the time interval discriminator is connected to a control input of a register which, in turn, is connected with its information input to an information output of the reversible counter, and with its information output to an information input of a digital display unit. A control unit of the digital display unit is connected to an output of an OR gate to one of whose inputs a signal is applied at a moment when a decision is made to terminate the analysis.

The above device operates as follows. Code pulses from the converter for converting the actual temperature of metals and alloys to a digital pulse code are fed through the synchronization unit to the inputs of the discriminator of local temperature increments and to the add and subtract inputs of the reversible counter which in response generates a parallel code of the actual temperature. Each time the temperature increment is equal to ±ε ₀ , at a respective output of the discriminator of local temperature increments there is formed a pulse which is applied to the reset inputs of the time interval discriminator.

The count input of the time interval discriminator is fed with synchronized clock pulses. After each resetting, the time interval discriminator again starts counting synchronized clock pulses. At the end of a predetermined time interval τ ₀ after the last resetting of the time interval discriminator, there appears a pulse at the output thereof, which occurs only if the next pulse does not arrive at the reset inputs of the time interval discriminator within the time interval τ ₀ . From the output of the latter, the pulse is applied to the control input of the register. The content of the reversible counter is entered into the register. As soon as the signal is applied from the output of the OR gate to the digital display unit, the latter produces a digital display of the result of the analysis.

Thus the device under review automatically determines the liquidus temperature only when on the cooling curve there occur such anomalous horizontal or sloping portions, whereat the metal temperature change during the time equal to τ ₀ does not exceed the value ±τ ₀ .

When an anomalous sloping portion occurs on the cooling curve, the liquidus temperature is determined by the temperature at the break point of the cooling curve, i.e. at the starting point of the anomalous portion. In this case, as follows from the foregoing description of the device, the result of analysis, entered into the register may differ from the liquidus temperature by ε ₀ . Therefore the ε ₀ threshold is set with due regard for accuracy requirements determining of the liquidus temperature.

In practice, on the cooling curves there also may be such anomalous sloping portions caused by the thermal effect of phase transformation of metals and alloys, whereat the temperature change during the time ε ₀ exceeds the ε ₀ threshold.

As pointed out above, an increase in the ε ₀ threshold is impermissible because it leads to a greater error in determining the liquidus temperature. Decreasing the ε ₀ threshold for the purpose of detection of the anomalous sloping portion having a steep droop is also impermissble in so far as in this case there may be detected an anomalous sloping portion of a short duration, caused by the pseudothermic effect, whereat the metal temperature at the break point of the cooling curve may be mistaken for the liquidus temperature.

Thus the known device does not provide for a sufficient confidence of detecting anomalous sloping portions caused by the thermal effect of phase transformation of metals and alloys.

Taken in combination with any known measuring devices for checking the carbon content in metal with reference to the liquidus temperature, the proposed device may perform the function of a digital sensor of carbon concentration in a closed control system for controlling steel melting processes with the use of a computer.