Questions tagged [tdr]

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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 (...
Rocketmagnet's user avatar
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0 answers
14 views

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 ...
Keyan's user avatar
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0 votes
1 answer
89 views

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 ...
cknz's user avatar
  • 19
1 vote
0 answers
60 views

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 ...
gamma_sponge's user avatar
4 votes
2 answers
148 views

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 ...
Anice41's user avatar
  • 95
19 votes
8 answers
4k views

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 ...
Jason's user avatar
  • 301
-1 votes
1 answer
206 views

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 ...
ron398's user avatar
  • 157
0 votes
3 answers
5k views

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 ...
ron398's user avatar
  • 157
0 votes
1 answer
393 views

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=...
ron398's user avatar
  • 157
0 votes
0 answers
108 views

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 ...
ron398's user avatar
  • 157
0 votes
0 answers
506 views

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 ...
chaperone's user avatar
0 votes
1 answer
91 views

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 ...
clubpenguin's user avatar
1 vote
1 answer
130 views

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 ...
John Hassell's user avatar
0 votes
3 answers
133 views

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?
Yoomo's user avatar
  • 363
0 votes
1 answer
94 views

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 ...
Yoomo's user avatar
  • 363
0 votes
3 answers
281 views

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 ...
electrococuk's user avatar
3 votes
4 answers
740 views

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?
Yoomo's user avatar
  • 363
0 votes
1 answer
138 views

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 ...
Yoomo's user avatar
  • 363
0 votes
2 answers
134 views

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 ...
Yoomo's user avatar
  • 363
1 vote
0 answers
60 views

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 ...
Yoomo's user avatar
  • 363
0 votes
1 answer
95 views

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?
electrococuk's user avatar
0 votes
2 answers
98 views

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 ...
EasyOhm's user avatar
  • 4,649
1 vote
0 answers
69 views

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 ...
CentralCee's user avatar
1 vote
1 answer
69 views

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 ...
Ageis's user avatar
  • 3,353
1 vote
0 answers
110 views

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 ...
Noj911's user avatar
  • 21
1 vote
1 answer
101 views

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 ...
user avatar
0 votes
0 answers
417 views

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 ...
aguntuk's user avatar
  • 13
2 votes
2 answers
163 views

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 ...
Estrozix's user avatar
3 votes
1 answer
501 views

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?
Erile's user avatar
  • 31
2 votes
1 answer
187 views

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 ...
bretddog's user avatar
  • 241
4 votes
1 answer
395 views

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 ...
bretddog's user avatar
  • 241
3 votes
1 answer
552 views

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 ...
Xiao Xiang's user avatar
4 votes
3 answers
2k views

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 ...
Landon Tholen's user avatar
1 vote
1 answer
3k views

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 ...
Rayne's user avatar
  • 183
4 votes
1 answer
194 views

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 ...
PlasmaHH's user avatar
  • 6,528
0 votes
2 answers
104 views

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 ...
Tom L.'s user avatar
  • 8,059