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	<title>Comments on: TDR circuit modification idea</title>
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	<link>https://www.epanorama.net/blog/2010/04/27/tdr-circuit-modification-idea/</link>
	<description>All about electronics and circuit design</description>
	<lastBuildDate>Wed, 22 Apr 2026 22:06:23 +0000</lastBuildDate>
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	<item>
		<title>By: Tomi Engdahl</title>
		<link>https://www.epanorama.net/blog/2010/04/27/tdr-circuit-modification-idea/comment-page-2/#comment-1846648</link>
		<dc:creator><![CDATA[Tomi Engdahl]]></dc:creator>
		<pubDate>Wed, 19 Feb 2025 09:40:48 +0000</pubDate>
		<guid isPermaLink="false">http://www.epanorama.net/blog/?p=1617#comment-1846648</guid>
		<description><![CDATA[How To Find Where A Wire In A Cable Is Broke. Which End Of The Broken Cable?
https://www.youtube.com/watch?v=FOzEpJogSFg]]></description>
		<content:encoded><![CDATA[<p>How To Find Where A Wire In A Cable Is Broke. Which End Of The Broken Cable?<br />
<a href="https://www.youtube.com/watch?v=FOzEpJogSFg" rel="nofollow">https://www.youtube.com/watch?v=FOzEpJogSFg</a></p>
]]></content:encoded>
	</item>
	<item>
		<title>By: Tomi Engdahl</title>
		<link>https://www.epanorama.net/blog/2010/04/27/tdr-circuit-modification-idea/comment-page-2/#comment-1835326</link>
		<dc:creator><![CDATA[Tomi Engdahl]]></dc:creator>
		<pubDate>Thu, 05 Sep 2024 04:08:22 +0000</pubDate>
		<guid isPermaLink="false">http://www.epanorama.net/blog/?p=1617#comment-1835326</guid>
		<description><![CDATA[50ps rise time using an ultra fast SiGe comparator http://www.starlino.com/build-a-really-fast-pulse-generator-50ps-rise-time-using-an-ultra-fast-sige-comparator.html]]></description>
		<content:encoded><![CDATA[<p>50ps rise time using an ultra fast SiGe comparator <a href="http://www.starlino.com/build-a-really-fast-pulse-generator-50ps-rise-time-using-an-ultra-fast-sige-comparator.html" rel="nofollow">http://www.starlino.com/build-a-really-fast-pulse-generator-50ps-rise-time-using-an-ultra-fast-sige-comparator.html</a></p>
]]></content:encoded>
	</item>
	<item>
		<title>By: Tomi Engdahl</title>
		<link>https://www.epanorama.net/blog/2010/04/27/tdr-circuit-modification-idea/comment-page-2/#comment-1819834</link>
		<dc:creator><![CDATA[Tomi Engdahl]]></dc:creator>
		<pubDate>Sat, 23 Dec 2023 14:03:59 +0000</pubDate>
		<guid isPermaLink="false">http://www.epanorama.net/blog/?p=1617#comment-1819834</guid>
		<description><![CDATA[https://hackaday.com/2021/05/08/calibrating-a-vna-the-proper-way/]]></description>
		<content:encoded><![CDATA[<p><a href="https://hackaday.com/2021/05/08/calibrating-a-vna-the-proper-way/" rel="nofollow">https://hackaday.com/2021/05/08/calibrating-a-vna-the-proper-way/</a></p>
]]></content:encoded>
	</item>
	<item>
		<title>By: Tomi Engdahl</title>
		<link>https://www.epanorama.net/blog/2010/04/27/tdr-circuit-modification-idea/comment-page-2/#comment-1819833</link>
		<dc:creator><![CDATA[Tomi Engdahl]]></dc:creator>
		<pubDate>Sat, 23 Dec 2023 14:03:31 +0000</pubDate>
		<guid isPermaLink="false">http://www.epanorama.net/blog/?p=1617#comment-1819833</guid>
		<description><![CDATA[https://hackaday.com/2023/12/18/simulate-a-better-termination/]]></description>
		<content:encoded><![CDATA[<p><a href="https://hackaday.com/2023/12/18/simulate-a-better-termination/" rel="nofollow">https://hackaday.com/2023/12/18/simulate-a-better-termination/</a></p>
]]></content:encoded>
	</item>
	<item>
		<title>By: Tomi Engdahl</title>
		<link>https://www.epanorama.net/blog/2010/04/27/tdr-circuit-modification-idea/comment-page-2/#comment-1740199</link>
		<dc:creator><![CDATA[Tomi Engdahl]]></dc:creator>
		<pubDate>Thu, 18 Nov 2021 13:20:17 +0000</pubDate>
		<guid isPermaLink="false">http://www.epanorama.net/blog/?p=1617#comment-1740199</guid>
		<description><![CDATA[https://en.wikipedia.org/wiki/Time-domain_reflectometer]]></description>
		<content:encoded><![CDATA[<p><a href="https://en.wikipedia.org/wiki/Time-domain_reflectometer" rel="nofollow">https://en.wikipedia.org/wiki/Time-domain_reflectometer</a></p>
]]></content:encoded>
	</item>
	<item>
		<title>By: Tomi Engdahl</title>
		<link>https://www.epanorama.net/blog/2010/04/27/tdr-circuit-modification-idea/comment-page-2/#comment-1732749</link>
		<dc:creator><![CDATA[Tomi Engdahl]]></dc:creator>
		<pubDate>Thu, 28 Oct 2021 08:45:39 +0000</pubDate>
		<guid isPermaLink="false">http://www.epanorama.net/blog/?p=1617#comment-1732749</guid>
		<description><![CDATA[Time-Domain Techniques for De-embedding and Impedance Peeling
https://teledynelecroy.com/doc/time-domain-de-embedding-and-peeling?utm_source=electronic-design&amp;utm_medium=ai-ads&amp;utm_content=wavepulser&amp;utm_campaign=2021-electronic-design-ai-ads-wavepulser

De-embedding is a common problem in making signal integrity measurements because often, the interconnection between the measurement instrument and the device under test (DUT) requires fixtures, cables, and/or probes. While usually it is not too much of a problem to calibrate the instrument to the end of the cables, which present a coaxial connector as the instrument port, the removal of what is between the instrument port and the desired reference plane of the DUT can prove problematic.

Adapter De-embedding

Many de-embedding applications involve the assumption that there is a two-port device (adapter) connected between one or more ports of the measurement instrument and the ports of the DUT

Time Gating

De-embedding is not a panacea. Usually, when connecting between instrument ports and the DUT, the desire is to have as transparent a connection as possible. This means a characteristic impedance as close to 50Ω as possible, and as little loss as possible. Otherwise, even if the s-parameters of the intervening device are known, it degrades measurement performance, even when employing proper de-embedding algorithms.

Even if the quality of the connection is good, there’s always the element of time. Even a well matched, low-loss adapter will have some amount of electrical length (i.e., it will take some amount of time for the waves to propagate through the adapter). In this situation, a very simple form of de-embedding, called time gating, can be used.

Impedance Peeling

While time gating is a very simple form of de-embedding used mostly to account for time delay (or electrical length), an improvement can be made by measuring and accounting for the actual impedance of the line, even as the impedance changes over time. This can be performed automatically and is called impedance peeling.]]></description>
		<content:encoded><![CDATA[<p>Time-Domain Techniques for De-embedding and Impedance Peeling<br />
<a href="https://teledynelecroy.com/doc/time-domain-de-embedding-and-peeling?utm_source=electronic-design&#038;utm_medium=ai-ads&#038;utm_content=wavepulser&#038;utm_campaign=2021-electronic-design-ai-ads-wavepulser" rel="nofollow">https://teledynelecroy.com/doc/time-domain-de-embedding-and-peeling?utm_source=electronic-design&#038;utm_medium=ai-ads&#038;utm_content=wavepulser&#038;utm_campaign=2021-electronic-design-ai-ads-wavepulser</a></p>
<p>De-embedding is a common problem in making signal integrity measurements because often, the interconnection between the measurement instrument and the device under test (DUT) requires fixtures, cables, and/or probes. While usually it is not too much of a problem to calibrate the instrument to the end of the cables, which present a coaxial connector as the instrument port, the removal of what is between the instrument port and the desired reference plane of the DUT can prove problematic.</p>
<p>Adapter De-embedding</p>
<p>Many de-embedding applications involve the assumption that there is a two-port device (adapter) connected between one or more ports of the measurement instrument and the ports of the DUT</p>
<p>Time Gating</p>
<p>De-embedding is not a panacea. Usually, when connecting between instrument ports and the DUT, the desire is to have as transparent a connection as possible. This means a characteristic impedance as close to 50Ω as possible, and as little loss as possible. Otherwise, even if the s-parameters of the intervening device are known, it degrades measurement performance, even when employing proper de-embedding algorithms.</p>
<p>Even if the quality of the connection is good, there’s always the element of time. Even a well matched, low-loss adapter will have some amount of electrical length (i.e., it will take some amount of time for the waves to propagate through the adapter). In this situation, a very simple form of de-embedding, called time gating, can be used.</p>
<p>Impedance Peeling</p>
<p>While time gating is a very simple form of de-embedding used mostly to account for time delay (or electrical length), an improvement can be made by measuring and accounting for the actual impedance of the line, even as the impedance changes over time. This can be performed automatically and is called impedance peeling.</p>
]]></content:encoded>
	</item>
	<item>
		<title>By: Tomi Engdahl</title>
		<link>https://www.epanorama.net/blog/2010/04/27/tdr-circuit-modification-idea/comment-page-2/#comment-1667799</link>
		<dc:creator><![CDATA[Tomi Engdahl]]></dc:creator>
		<pubDate>Fri, 17 Jan 2020 14:59:17 +0000</pubDate>
		<guid isPermaLink="false">http://www.epanorama.net/blog/?p=1617#comment-1667799</guid>
		<description><![CDATA[This circuit at https://www.epanorama.net/circuits/tdr.html is designed to generate repeating pulses. 
The time between pulses depends on the pulse length. The time between pulses is approximately 200 times the pulse length. 
Thank you for your feedback.

I don&#039;t have ready made plans for triggerable single pulse sending application. 
I think should be doable in way or another...]]></description>
		<content:encoded><![CDATA[<p>This circuit at <a href="https://www.epanorama.net/circuits/tdr.html" rel="nofollow">https://www.epanorama.net/circuits/tdr.html</a> is designed to generate repeating pulses.<br />
The time between pulses depends on the pulse length. The time between pulses is approximately 200 times the pulse length.<br />
Thank you for your feedback.</p>
<p>I don&#8217;t have ready made plans for triggerable single pulse sending application.<br />
I think should be doable in way or another&#8230;</p>
]]></content:encoded>
	</item>
	<item>
		<title>By: Jeff Hurckes</title>
		<link>https://www.epanorama.net/blog/2010/04/27/tdr-circuit-modification-idea/comment-page-2/#comment-1667792</link>
		<dc:creator><![CDATA[Jeff Hurckes]]></dc:creator>
		<pubDate>Fri, 17 Jan 2020 12:38:50 +0000</pubDate>
		<guid isPermaLink="false">http://www.epanorama.net/blog/?p=1617#comment-1667792</guid>
		<description><![CDATA[So, I&#039;ve been looking over this project and have a question.  Is the TDR circuit a single shot, or does it send repeating pulses? If it is repeating, could it be designed to be a triggerable single shot?  I&#039;d like to use this with a Fluke ScopeMeter in testing 75 ohm coax.]]></description>
		<content:encoded><![CDATA[<p>So, I&#8217;ve been looking over this project and have a question.  Is the TDR circuit a single shot, or does it send repeating pulses? If it is repeating, could it be designed to be a triggerable single shot?  I&#8217;d like to use this with a Fluke ScopeMeter in testing 75 ohm coax.</p>
]]></content:encoded>
	</item>
	<item>
		<title>By: Tomi Engdahl</title>
		<link>https://www.epanorama.net/blog/2010/04/27/tdr-circuit-modification-idea/comment-page-2/#comment-1599635</link>
		<dc:creator><![CDATA[Tomi Engdahl]]></dc:creator>
		<pubDate>Fri, 10 Aug 2018 14:40:05 +0000</pubDate>
		<guid isPermaLink="false">http://www.epanorama.net/blog/?p=1617#comment-1599635</guid>
		<description><![CDATA[Pocket-Sized Instrument Packs TDR and Fast-Edge Generator
https://www.mwrf.com/test-measurement/pocket-sized-instrument-packs-tdr-and-fast-edge-generator?NL=MWRF-001&amp;Issue=MWRF-001_20180719_MWRF-001_299&amp;sfvc4enews=42&amp;cl=article_1_b&amp;utm_rid=CPG05000002750211&amp;utm_campaign=18698&amp;utm_medium=email&amp;elq2=b82ebfb2092c41718c5a529859887a62

This low-cost fast-edge pulse generator provides the means to measure PCB dielectric constants and the impedances of cables and interconnections.

PerfectPulse Fast Edge Signal Generator from Picotest Corp. It provides square waves with 32-ps rise and fall times and the pulse edges needed to precisely measure things like cable and printed-circuit-board (PCB) transmission-line lengths and impedances, and even the dielectric constant of PCBs and other materials. For all of its capabilities, the PerfectPulse generator is remarkably compact, small enough to fit in a shirt pocket.

The PerfectPulse signal generator (Fig. 1) generates pulsed output signals at 50 mV and 50 Ω with no overshoot or undershoot—the kind of square waves that are extremely useful for performing time-domain-reflectometry (TDR) and time-domain-transmission (TDT) measurements utilizing a high-speed, real-time oscilloscope with sufficient bandwidth. The signal generator will be shipped with a 10-GHz power splitter so that the dual test signals can be used for high-performance TDR and TDT measurements on PCBs and PCB signal traces, as well as to measure the lengths of cables and signal traces, plus verify the quality of crimps in cables.

The J2151A PerfectPulse signal generator can be used for oscilloscope probe calibration. The compact signal generator is compatible with all 50-Ω probes, for convenient signal injection and noninvasive stability measurements on circuits.

The one-port P2100A test probe (Fig. 2) supports connections to 1.5 GHz with almost no capacitive loading: less than 1-pF capacitance, and typically only 420-fF capacitive loading.]]></description>
		<content:encoded><![CDATA[<p>Pocket-Sized Instrument Packs TDR and Fast-Edge Generator<br />
<a href="https://www.mwrf.com/test-measurement/pocket-sized-instrument-packs-tdr-and-fast-edge-generator?NL=MWRF-001&#038;Issue=MWRF-001_20180719_MWRF-001_299&#038;sfvc4enews=42&#038;cl=article_1_b&#038;utm_rid=CPG05000002750211&#038;utm_campaign=18698&#038;utm_medium=email&#038;elq2=b82ebfb2092c41718c5a529859887a62" rel="nofollow">https://www.mwrf.com/test-measurement/pocket-sized-instrument-packs-tdr-and-fast-edge-generator?NL=MWRF-001&#038;Issue=MWRF-001_20180719_MWRF-001_299&#038;sfvc4enews=42&#038;cl=article_1_b&#038;utm_rid=CPG05000002750211&#038;utm_campaign=18698&#038;utm_medium=email&#038;elq2=b82ebfb2092c41718c5a529859887a62</a></p>
<p>This low-cost fast-edge pulse generator provides the means to measure PCB dielectric constants and the impedances of cables and interconnections.</p>
<p>PerfectPulse Fast Edge Signal Generator from Picotest Corp. It provides square waves with 32-ps rise and fall times and the pulse edges needed to precisely measure things like cable and printed-circuit-board (PCB) transmission-line lengths and impedances, and even the dielectric constant of PCBs and other materials. For all of its capabilities, the PerfectPulse generator is remarkably compact, small enough to fit in a shirt pocket.</p>
<p>The PerfectPulse signal generator (Fig. 1) generates pulsed output signals at 50 mV and 50 Ω with no overshoot or undershoot—the kind of square waves that are extremely useful for performing time-domain-reflectometry (TDR) and time-domain-transmission (TDT) measurements utilizing a high-speed, real-time oscilloscope with sufficient bandwidth. The signal generator will be shipped with a 10-GHz power splitter so that the dual test signals can be used for high-performance TDR and TDT measurements on PCBs and PCB signal traces, as well as to measure the lengths of cables and signal traces, plus verify the quality of crimps in cables.</p>
<p>The J2151A PerfectPulse signal generator can be used for oscilloscope probe calibration. The compact signal generator is compatible with all 50-Ω probes, for convenient signal injection and noninvasive stability measurements on circuits.</p>
<p>The one-port P2100A test probe (Fig. 2) supports connections to 1.5 GHz with almost no capacitive loading: less than 1-pF capacitance, and typically only 420-fF capacitive loading.</p>
]]></content:encoded>
	</item>
	<item>
		<title>By: Tomi Engdahl</title>
		<link>https://www.epanorama.net/blog/2010/04/27/tdr-circuit-modification-idea/comment-page-2/#comment-1595242</link>
		<dc:creator><![CDATA[Tomi Engdahl]]></dc:creator>
		<pubDate>Mon, 25 Jun 2018 13:53:10 +0000</pubDate>
		<guid isPermaLink="false">http://www.epanorama.net/blog/?p=1617#comment-1595242</guid>
		<description><![CDATA[Send known rise-time edges down transmission lines
https://www.edn.com/electronics-products/other/4460757/Send-known-rise-time-edges-down-transmission-lines

High-speed signals such as microwave carriers and digital data streams lose fidelity as they travel. Losses from PCB traces, connectors, and cables need measurements on those losses, the reult of impedance. For $3500, you can use the J2151A PerfectPulse to send a signal with known rise times through a transmission path. From those pulses, you can characterize the path.

USB powered and about the size of a flash drive, PerfectPulse generates a stream of square waves with 32 ps rise times at repetition rates of 1 kHz, 10 kHz, 100 kHz, 1 MHz, and 10 MHz.
The J2151A&#039;s output amplitude is 0 to 500 mV, trimmed to 1% ±2.5 mV.

The PerfectPulse comes with a 10 GHz power splitter for making time-domain reflectometery (TDR) measurements and a demo board that has PCB traces of known impedance.
Using a probe such as the Picotest P2100A 50 Ω power-distribution network (PDN) probe or probes from other manufacturers, you can inject the J2151A&#039;s signal into your DUT.

https://www.picotest.com/products_J2151A.html]]></description>
		<content:encoded><![CDATA[<p>Send known rise-time edges down transmission lines<br />
<a href="https://www.edn.com/electronics-products/other/4460757/Send-known-rise-time-edges-down-transmission-lines" rel="nofollow">https://www.edn.com/electronics-products/other/4460757/Send-known-rise-time-edges-down-transmission-lines</a></p>
<p>High-speed signals such as microwave carriers and digital data streams lose fidelity as they travel. Losses from PCB traces, connectors, and cables need measurements on those losses, the reult of impedance. For $3500, you can use the J2151A PerfectPulse to send a signal with known rise times through a transmission path. From those pulses, you can characterize the path.</p>
<p>USB powered and about the size of a flash drive, PerfectPulse generates a stream of square waves with 32 ps rise times at repetition rates of 1 kHz, 10 kHz, 100 kHz, 1 MHz, and 10 MHz.<br />
The J2151A&#8217;s output amplitude is 0 to 500 mV, trimmed to 1% ±2.5 mV.</p>
<p>The PerfectPulse comes with a 10 GHz power splitter for making time-domain reflectometery (TDR) measurements and a demo board that has PCB traces of known impedance.<br />
Using a probe such as the Picotest P2100A 50 Ω power-distribution network (PDN) probe or probes from other manufacturers, you can inject the J2151A&#8217;s signal into your DUT.</p>
<p><a href="https://www.picotest.com/products_J2151A.html" rel="nofollow">https://www.picotest.com/products_J2151A.html</a></p>
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