Long Delay Echos (LDE) TiVo, etc - Page 1
Forum section: electronics / projects

author: cncjerry
author_rank: Unknown
timestamp: October 30, 2017, 06:37:22 pm
content: Years ago (late 90's, early 2000's) there was discussion on the ham forums about Long Delay Echos (LDE). These are echos that are heard on transmissions that are greater than let's say one second.For quite a while I was hearing an LDE on the 80M band. I would transmit CQ and it would bounce right back to me, slightly modulated, 2.3 seconds later, at 40 over S9. I remember talking and demonstrating this on the phone with the author of the Radio Handbook, can't remember his name now, he since died and was in his 90's back then. he was living in Santa Rosa not far from me in Sausalito, CA. The strangest LDE was one that happened over an hour after I had a QSO (again on 80M) where I could hear my side of my entire QSO with a local operator. Let me tell you, that freaked me out, hearing my voice, S9+ coming through my receiver. I thought someone was recording me and playing it back. I had been talking to a freiend, he signed, and I had the receiver sitting on the same frequency, and all of a sudden I could hear my voice and it continued for an hour. It turned out my wife had recorded something on TiVo and had played it back. My QSO was recorded with her TV show.I later figured out that it was coming from TiVo. My coax ran up to the roof bundled with my Directv receiver cables. I guess this was helping to couple it into the TiVo and the 2.3 second delay was what helped us figure it out as it was approximately the same delay introduced when TiVo recorded live TV. Once I figured all this out I sent a note to CQ magazine explaining how the LDEs where being created. Every few years I still see someone talking about some LDE coming from a solar system Ionized shockwave etc.The reason I bring this up as I was getting ready to pitch my TiVo and was wondering if someone hearing this story would want to hack a TiVo to record live RF. I guess you would have to translate the signal either into the TV channels or into the TiVo baseband which must be around the color burst 3.8Mhz frequency. Years ago there was a VCR system that was used to record a wide swath of RF and like my LDE from the TiVo, you were able to tune over something like 500Khz, definitely wider bandwidth that is available with a sound card.I think I have two TiVos that had the hard drives stripped and if someone wanted one, they are welcome to pick them up or I would ship them.Let me tell you, I struggled with the original CW LDE for quite a while. It made 80M CW almost impossible during certain times of the day though I didn't know it was only when the Tivo was powered on.Jerry

author: StillTrying
author_rank: Super Contributor
timestamp: October 30, 2017, 09:28:09 pm
content: Was the "recorded" echo visible on the picture, I can't see how it wouldn't be.Long Delayed Echoes have been heard since 1927, the TiVo came out in 1999.

author: cncjerry
author_rank: Unknown
timestamp: October 30, 2017, 11:48:39 pm
content: I never heard any complaints from my wife about picture interference. Also, the newer DVRs from Directv don't do it.