Questions tagged [tdr]
The tdr tag has no usage guidance.
36
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2
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Can I measure the internal termination resistance of a MIPI receiver?
This question is further to: How accurate are internal terminators on chips with high speed differential inputs?.
I would like to measure the actual termination resistance inside one of these chips (...
0
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0
answers
15
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Origin (t=0) of the time axis shifted after TDR on two sets of different S11 data
I have two sets of S11 data (S1P format) which are measured on an open co-axial cable (~ 20 cm long) and open-end as reference (see the hand-draw figures below) correspondingly. I used the Python skrf ...
0
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1
answer
92
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How to read a TDR report?
This is the report generated from Keysight ADS. I can see the reflections from the vias and layer change (impedance swing) but I couldn't figure out the impedance of the actual traces. Also, why are ...
1
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0
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60
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Time domain reflectometer (TDR) to check health of voice coil
I have some large voice coils in which the insulation is failing. We first notice this when the amplifier trips off on over current (short to ground.)
I'm wondering if before the catastrophic fault ...
4
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2
answers
148
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Time domain reflectometry and resolution
Regarding the temporal (and consequently spatial) resolution of a TDR system, I've read from different sources that the maximum resolution achievable is half of the rising time of the input step ...
19
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8
answers
4k
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Electricity only flows in a complete circuit, so how does TDR (time domain reflectometery) work?
In high school we were all taught that electricity only flows in a loop. But it seems that one can send a "pulse" down an open conductor. This is used in a time-domain reflectometer. How is ...
-1
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1
answer
206
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what is the alternative method for time domain reflectometry
I have read that TDR is problematic because if we have many transmission lines in series which cause discontinuity to the source resistance ,then the closer TL's will mask the reading of the far TL ...
0
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3
answers
5k
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Frequency domain S11 conversion to time domain TDR
Below we see the S11 plot of a transmission line, the Wikipedia definition of the reflection coefficient as a function of S-params.
As I see it, the S-param frequency domain plot comes from the time ...
0
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1
answer
396
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How can I convert from voltage TDR into impedance TDR
Based on the circuit below I have built the voltage based TDR diagram.
Then I went to the ADS TDR simulation and constructed by the manual the circuit below.
In the ADS circuit they say that IMPEDANCE=...
0
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0
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108
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time domain reflectometry interpretation of a simple circuit
I have constructed the following circuit in HSPICE,and it gives me the following waveform
I know that we have the first wave hit node 3 then it goes back and again to node 3.
But how we construct the ...
0
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0
answers
507
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Op- amp comparators and temperature dependent resistor
The circuit in Fig 1 consists of a temperature dependent resistor (TDR). Compute the:
temperature at which the comparator will change state.
2)supply voltage required for a 40°C trip point in Figure ...
0
votes
1
answer
91
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Three wire parallel transmission line (TDR)
I have a three wire parallel transmission line with a length of around 1000m. The wires are really close to each other. I want to sample the response of the transmission line for two different pulse ...
1
vote
1
answer
130
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Could a time-domain reflectometer, with no access to earth-ground, indicate if a long-wire is attached to the end of a long steel beam?
Without using any other wiring, optics, RF, sound, or vibration, I need to know if a 100 meter length of electrical wire is attached to the end of a 50 meter long steel beam.
I only have physical ...
0
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3
answers
133
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time domain reflectometry on long cables
Is it possible to use time domain reflectometry on cables with a length of more than 100km?
What kind of problems do time domain reflectometers on that long cables face?
0
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1
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94
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TDR unexpected results
I am using a signal generator to generate a long square pulse that is fed into a long transmission line consisting of two parallel wires. The transmission line is approximately 1km long. The near end ...
0
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3
answers
281
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Measuring length of two wires inside copper with a TDR
I have a cable as in the drawing.
The black parts are insulators and the brown parts are copper, so there is a big copper cable and inside are two smaller copper cables.
When the big copper cable is ...
3
votes
4
answers
744
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Determining conductance / capacitance and inductance per unit length
How do you determine conductance / capacitance and inductance per unit for a cable experimentally?
Is there a way to determine them with only a oscilloscope and a pulse generator?
0
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1
answer
138
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time domain reflectometer determining impedance
Lets say I have a 1km long transmission line with a characteristic impedance of 50ohm. With a pulse generator I inject a really long pulse (30µs) the pulse generators termination is also 50 ohm. The ...
0
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2
answers
134
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Time domain reflectometer looking for faults
I have a TDR with a sampling frequency of 200MHz that equals 1 sample very 5 ns. When I use a really long square wave the response will look like the left plot. Where delta t is the time of ...
1
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0
answers
60
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time domain reflectometry pulse
Today I investigated a cable which is around 900m long. I used a TDR that injects a needle pulse into the system with a width of around 40ns. The needle pulse had an amplitude of around 2V. A ...
0
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1
answer
95
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time domain reflectometry pulse shape
Alot of TDRs use square waves or needle like pulses for length determination. Why are not other pulse shapes like sine or triangle used?
0
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2
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98
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TDR to detect broken LED
I have a string of 10 LEDs in series. Occasionally some LEDs area breaking and the entire string stops working. Can a TDR (Time Domain Reflectometry ) or other measurement be used to determine which ...
1
vote
0
answers
69
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Detecting an electrical connection without a complete circuit
Wired Fencing
In a regular (wired) fencing system (for sabre and foil,) contact is determined simply by applying a current to the weapon through a wire and forming a circuit between a conductive ...
1
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1
answer
69
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using sig generator and scope as TDR for troubleshooting ethernet
I had some problems with a new run of cat5e. I have already established it's definitely a damaged cable using a cheap network continuity tester and double checking my wiring and crimps.
I saw on ...
1
vote
0
answers
111
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Simulating cable length during TDR testing
I am trying to create a circuit that can be used as part of a TDR simulator.
What I need to know is if it is possible for the pulse that is sent out by the TDR equipment to be delayed by a piece of ...
1
vote
1
answer
101
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Different types of reflection/TDR casic
I am trying to understand the theory of operation of a time domain reflectometer (TDR).
TDR is a time domain instrument with measurement the impedance versus the distance. If with a VNA one can ...
0
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0
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417
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How to setup and simulate differential TDR (Time Domain Reflectometry) in Cadence
I want to do differential TDR simulation in cadence virtuoso. I have a differential channel, made of Tlines and interconnects (passive componenets). How to setup the TDR simulation to get impedance ...
2
votes
2
answers
164
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High-Speed electronics - Reflections in T-intersection
I'm currently attending a course on "experimental problem solving" and we just started talking about TDR (time domain reflectometry). I do understand that reflections occur whenever there is a change ...
3
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1
answer
501
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frequency and type of pulse for time domain reflectometer (TDR) [closed]
I would like to apply the time domain reflectometry method in an fpga. However, I could not find information about the frequency and type of pulse used by reflectometer.
Can anyone give me a guide?
2
votes
1
answer
187
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Time domain reflectometry (TDR), initial pulse slope
A ~100kHz square wave through a 100m open end coax (RG-58) produces a slightly sloped shoulder during the time from initial pulse until reflected pulse (A-B), and from initial pulse drops until ...
4
votes
1
answer
395
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Time domain reflectometry (TDR), pulse shape
Considering this coax cable open end reflection. What are the correct explanations for the flatter rise time, the rounding of the first reflection, and the much smaller what I assume to be secondary ...
3
votes
1
answer
553
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How can I use the TDR result to evaluate the effect of impedance discontinuity?
Only the left half is relevant.
Like mentioned before,I want to check out if reflection is one of the reason that deteriorates the signal integrity of high-speed signal.One way that has been come up ...
4
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3
answers
2k
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Is it possible to measure TDR without a specialized device?
I've seen dedicated devices for measuring TDR and even layer 2&3 network switches with the TDR capability.
My question is what would prevent a standard home router from being programmed to measure ...
1
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1
answer
3k
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Simulation of TDR using LTSpice
I'm trying to simulate a TDR based on the figure below, and one of the scenarios is a short circuit. The simulation should last for 140ns.
The parameters are
\$Z_A = 50 \Omega \$
\$T_A = 5ns\$
\$Z_B ...
4
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1
answer
194
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What level of a square wave signal should be safe for TV receivers?
I am experimenting a bit with TDR (time domain reflectometry) and for it I am generating a square wave with up to 10kHz and a rise time of about 1-2ns.
Now I would like to put that thing to use and ...
0
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2
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104
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TDR Device parameters [closed]
We are currently intending to purchase a TDR device (or maybe 2) to measure the impedances of various traces on PCBs but we are just at the beginning. Can you recommend some good devices or devices ...