Thanks, Jimmy, for this “in depth” Master Class on the geophys work on the Roman Villa at Broughton. It’s great that the new format Time Team provides such opportunities to hear a more detailed story.
Absolutely fascinating. Why couldn't we have had something like this during the time team series!!!.. I'm all for showing how you got the results and why they couldn't have been anything else.
Sorry, I missed the Live Chat but, if there are any questions, post a comment and I'll do my best to answer. I've had a look back through the chat log and, to kick off, I have these: - the reason we can't emulate a CT scan type of result is that they require the ability to image from multiple angles around the target, whereas "typically" we are stuck to shooting top-down. - we do use lidar and the drone collected photogrammetry from Adam (often lidar for wider landscape context and Adam's data for site-centred detail). - a hat indoors is a necessity in my badly planned office where a 4000K spotlight shines directly down on my shiny bonce ;-)
Questions for you Jimmy. In almost every geophys plot I see, there's always something that shows up or sticks out to me, that no one on the show seems to notice or comment on. Off camera, is there a lot of "What on earth is that?". Do the archaeologist ask about more anomalies? Does every feature on a geophys plot get scrutinized? I couldn't help but notice when you were going through the villa plots, at about .7 or .8 meters there was a parallel line to what you termed the western boundary wall. It was faint, but it was there, and about the same distance from the boundary wall as the width of the eastern wing of the villa. Really makes me curious. And thanks for taking the time to share that Jimmy, the technology these days is truly amazing.
@@RobBoudreau yes, lots of discussion between the team and rarely is the final interpretation actually "final". There will be a few iterations as more information comes to light. In general, we see lots of evidence for more recent activity in data plus things like old field boundaries and natural responses which we will discount pretty quickly but they can often be more obvious than the archaeology we are interested in. Also, we 'see' so much with these newer systems that the final interpretation and reporting is a long process. On this site there was lots of ancillary stuff (e.g. the drainage/water management) and multiple phases which made it trickier to analyse; in this video we stick to the discussion points we'd had on site but stuff like those faint linears will end up in the final record of what was found and as investigations continue their significance may change. But at the time, that appeared quite different in the radargrams from the "boundary wall" and the trench that went in over the wall was pretty clean unlike those over the other ranges.
This is one of the best Time Teams ever! I love the science part and imaging is becoming more and more important since it reduces the time spent digging in the wrong places _and_ sets up future digs.
What a great talk through that was... Many thanks for explaining so clearly what is involved and the challenges you were facing , in order to establish the story of the site.
This is GREAT! Many thanks, Jimmy, this really helps me understand how things have progressed over the past few years. What would you, in an ideal world, like to see develop in the next few years?
This is a very interesting video especially because I am Swedish and because you are using the Malå radar. Malå is a town in my country. I have seen Time Team four a lot of years. But I miss the old crew thou like Sir Tony, and all the others.
Yep, that's where our factory is! The MALÅ part of our company can trace its heritage back to 1937 when it was an SGU office in Malå dabbling in electromagnetics.
Thank you…really helpful to have a tech update on what radar can do. In future please could you ensure that any info at the top of screen eg axis info can be seen. Jinx
Typing as a seismic data processor of 40+ years experience, is it worth using any of the data processing techniques, deconvolution for example, to clean up the multiples, simple migration algorithms to collapse diffractions. Or is the possible benefit just not worth the extra processing? Many thanks for the presentation and many thanks to John Gator for his efforts over the years.
We do use a lot of the same processing methods, yes; albeit adapted for EM propagation. Before slicing the data have had gain applied to counter the spreading wave front and exponential signal decay, a bit of bandpass filtering, a running background removal, migration and a hilbert transform. That said, the radargrams you see in the video have only had a gain and bandpass applied. This is a matter of choice but I prefer to look at the minimally processed radargrams most of the time.
Thanks for the detailed explanation of the equipment and data interpretation. Something that is missed from the show as it shows how much the science supports the diggers choices.
A big thank you Jimmy, that was absolutely fascinating and very informative. Well presented too. As a next step it would be great to get the GPR and magnetometry data and air photos all layered together in the same way so we could see what that reveals. Any chance of that? Go on, buy Stewart a pint :-)
Very interesting. Thank you. Do you think that a maser would work for GPR purposes? Given the narrow beam produced, a portable one could be slung under a drone, to permit rapid GPR. That may be optimistic because I am assuming that the reflected signal could be readily detected above the ground. That could true with a maser however, with its precise frequency operation. Lasers could also be used for 'field scanning' purposes, I believe. Much quicker than walking.
How much is the result influenced by moisture? Is it better when it is dry or when the soil is wetter? It looks like, despite the GPS, the terrain is covered in parallel, straight paths. What is the reason for this? Can the result be improved if (especially linear features) are surveyed from different angles? The wheel should be compact, but can the result be improved if (more) receivers record data at a distance from the transmitter? Like with sonar, for example. Is a single frequency used or are there different frequencies depending on the type of bottom and targets? I suppose this would have an impact on penetration depth and resolution.
The moisture question is tricky - it depends so much on the method in use and the target you're going after. For example, resistance survey (with the "electric walkingframe") can struggle if it's very dry or very wet as you lose contrast between the archaeology and surrounding soils; you want 'Goldilocks' weather for that to work at its best. For GPR, generally speaking, wetter is worse as the ground conductivity goes up and the signal is attenuated quicker so you lose penetration. The straight‐path survey mode is really to ensure efficient and even coverage but on arable land it is also a practical consideration: going parallel to dominant plough-direction allows us to minimise the harsh impact of the near-surface agricultural disturbance and going across the plough-lines can be really uncomfortable for the operator and the kit as you bounce over the ridges and ruts. These multichannel systems are designed with antenna centres so close that the improvement gained from also running in another direction doesn't normally warrant the additional time and effort. And you can set-up a system to use a different frequency to improve either resolution or depth but for the majority of archaeology the sweetspot tends to be around the 500MHz mark. There are multifrequency systems available too but there are pros and cons to both approaches. There probably isn't much advantage to shooting different locations as, again, it would require more complex processing to correct for the various offsets (rather than effectively treating send and receive as being at the same location) so may not pass the cost/benefit analysis. But who knows what the future holds for our tech...? 🙂
Are any of the filters (I saw bandpass) or processing you use similar to what is done for seismic processing. I guess you are almost doing seismic recording just at shallow depths with finer detail (I'm from both a Seismic and Archaeology background but never really worked with the acquisition sides of either)
Yes, very similar in principle except of course we are operating in the electromagnetic realm and detecting those contrasts rather than changes in density/elasticity. So the processing steps and filters used are often the same but adapted for that fundamental difference.
Doubt you can mount the magnetometer and the GPR on the same survey equipment. The magnetometer equipment has to have a very low magnetic signature itself, the magnetic field it's measuring is relatively week. The GPR kit has significant amounts of electronic equipment, particularly transmitters, which will have significant magnetic fields. If the results contain sufficiently accurate position data, the two data sets can probably be overlaid accurately post capture though.
There are groups who have attempted this but, as Harry says, you need a good offset between the 2 sets of hardware otherwise the mag data becomes unusable.
@Jimmy Adcock: A question to Jimmy as a *theoretical* ;-) physicist with a PhD and 20 years modelling experience. Would it not help to do the field from left to right and then perpendicular from top to bottom and then merge both sets of scans to get a better noise-signal ratio. It should be possible to precisely match the location of both sets if you put at every 10 meters or so, an object in the ground emmiting a very strong signal which u can use to merge the sets in space? I am just curious... Best wishes from Luxembourg, Tom
These multichannel systems are designed to be truly 3D which means we space the antenna pairs within 1/4 of the dominant wavelength and collect data equally inline and crossline. Then we can construct the radargrams in any orientation we wish. Arguably in an ideal world there maybe some slight improvements to be had by repeating in another orientation (and we can have very accurate absolute positioning available so little need for ground referencing) but the reality is that (when we review what is found and missed in previous datasets) for archaeological targets it's very unlikely to provide huge gains or alter your final interpretation and doesn't justify doubling survey times. Specifically on this site, collecting a dataset across the dominant plough direction would most likely introduce more noise.
@@jimmyadcockABEM thx for the quick reply. That's what I thought, theoretically it should improve noise-signal but empirically could just be minimally plus other issues. OK, u kind of do already both directions because u have a 3D sensoring device. So there is a preferred plowing direction for centuries? I guess the direction is where they can plow the longest in one go so you minimize the turns? I am not a farmer. Can it change? Do some fields have a strong preference for directions and others are either way? I would have thought that the dominant plough direction would generate certain types of correlated signals that can be filtered out? Also, if you had a method to quantitatively distinguish between plough direction and the other, you could find out how deep the plough affected the ground and which is virgin ground by doing both directions? wld this help archeologists? sorry just brainstorming...
@@tweidig I'm no expert on arable (probably more of a Stewart question) but it's a combination of slope and space. You'd want to do the longest runs possible most of the time but you also want to avoid ploughing across steeper slopes. Generally on sloping sites the agriculture is in the same direction from evidence of medieval ridge and furrow through to modern mechanical ploughing. On flatter sites you might see different directions. But the problem with attempting to define a filtering algorithm is that, over the years, the ploughing doesn't quite line up both in terms of spacing and orientation. And the 'noise' we record from the agriculture is not just derived from the present regime but also historic ploughing which has caused changes to the structure and composition of soils. All part of the 'fun' 😀
Hi, have ALWAYS loved Time Team, Messrs Gator and Ainsworth were always seen as USEFUL by Phil Harding but, I "Side" with Phil... "Just dig a bloody hole" lol !!!!
If we wanted someone giving a lecture on blah blah blah we would have gone to Uni but we want to see what you found on the dig, eg; pottery bones trinkets etc etc.
I'm sure you must realise that you are under no compulsion to watch if you have no interest in what is being said. (And a glance at most of the other comments should show you that you cannot really claim to speak for what "we" want.)
Personally I found this presentation one of the most interesting and informative so far. It speaks to the real archaeologists who are interested in the depth of information and findings rather than the superficialities.
Great to have a technical presentation of equipment used
Thanks, Jimmy, for this “in depth” Master Class on the geophys work on the Roman Villa at Broughton. It’s great that the new format Time Team provides such opportunities to hear a more detailed story.
Absolutely fascinating. Why couldn't we have had something like this during the time team series!!!.. I'm all for showing how you got the results and why they couldn't have been anything else.
Thanks, Jimmy. That was really fun and informative. Someone, please put in a test pit on that ambiguous part and report back!
Great to have the extra detail and thought processes behind things, More masterclasses please
Sorry, I missed the Live Chat but, if there are any questions, post a comment and I'll do my best to answer. I've had a look back through the chat log and, to kick off, I have these:
- the reason we can't emulate a CT scan type of result is that they require the ability to image from multiple angles around the target, whereas "typically" we are stuck to shooting top-down.
- we do use lidar and the drone collected photogrammetry from Adam (often lidar for wider landscape context and Adam's data for site-centred detail).
- a hat indoors is a necessity in my badly planned office where a 4000K spotlight shines directly down on my shiny bonce ;-)
Questions for you Jimmy. In almost every geophys plot I see, there's always something that shows up or sticks out to me, that no one on the show seems to notice or comment on. Off camera, is there a lot of "What on earth is that?". Do the archaeologist ask about more anomalies? Does every feature on a geophys plot get scrutinized?
I couldn't help but notice when you were going through the villa plots, at about .7 or .8 meters there was a parallel line to what you termed the western boundary wall. It was faint, but it was there, and about the same distance from the boundary wall as the width of the eastern wing of the villa. Really makes me curious.
And thanks for taking the time to share that Jimmy, the technology these days is truly amazing.
@@RobBoudreau yes, lots of discussion between the team and rarely is the final interpretation actually "final". There will be a few iterations as more information comes to light. In general, we see lots of evidence for more recent activity in data plus things like old field boundaries and natural responses which we will discount pretty quickly but they can often be more obvious than the archaeology we are interested in. Also, we 'see' so much with these newer systems that the final interpretation and reporting is a long process. On this site there was lots of ancillary stuff (e.g. the drainage/water management) and multiple phases which made it trickier to analyse; in this video we stick to the discussion points we'd had on site but stuff like those faint linears will end up in the final record of what was found and as investigations continue their significance may change. But at the time, that appeared quite different in the radargrams from the "boundary wall" and the trench that went in over the wall was pretty clean unlike those over the other ranges.
@@jimmyadcockABEM Thanks for the great answer. Really looking forward to what you found in the new sites! Cheers!
Thank you for sharing! Geophys is fascinating and I really enjoyed the deep dive into how the technology works.
Thank you for going into the images like that.
This is one of the best Time Teams ever! I love the science part and imaging is becoming more and more important since it reduces the time spent digging in the wrong places _and_ sets up future digs.
What a great talk through that was... Many thanks for explaining so clearly what is involved and the challenges you were facing , in order to establish the story of the site.
Thank you, TT! That was very interesting - I think whether you've seen the episode or not.
I love this feature. So well presented by Jimmy. Thank you.
Thank you, that was very informative
Great job as always
Great information and explanation here.
great presentation jimmy
i have been a bit busy past few weeks so i am catching up, love these time team exclusives. thanks time team. ;-)
Very interesting. Thanks for the post
thanks Jimmy. very interesting and a clear explanation
Absolutely fascinating, thank you for sharing this with us. 👍
So MANY questions answered. Thank you very much.
This is great!
Very informative thank you
Any time Mister Jimmy wants to talk, I'll be happy listen!
This is GREAT! Many thanks, Jimmy, this really helps me understand how things have progressed over the past few years. What would you, in an ideal world, like to see develop in the next few years?
LOVE the in depth content we wouldn't get on the telly
This is a very interesting video especially because I am Swedish and because you are using the Malå radar. Malå is a town in my country. I have seen Time Team four a lot of years. But I miss the old crew thou like Sir Tony, and all the others.
Yep, that's where our factory is! The MALÅ part of our company can trace its heritage back to 1937 when it was an SGU office in Malå dabbling in electromagnetics.
One more comment. I have to say Phil was always too hard on the GeoPhys team. You are awesome!
Thanks.
Thank you…really helpful to have a tech update on what radar can do. In future please could you ensure that any info at the top of screen eg axis info can be seen. Jinx
Typing as a seismic data processor of 40+ years experience, is it worth using any of the data processing techniques, deconvolution for example, to clean up the multiples, simple migration algorithms to collapse diffractions. Or is the possible benefit just not worth the extra processing?
Many thanks for the presentation and many thanks to John Gator for his efforts over the years.
We do use a lot of the same processing methods, yes; albeit adapted for EM propagation. Before slicing the data have had gain applied to counter the spreading wave front and exponential signal decay, a bit of bandpass filtering, a running background removal, migration and a hilbert transform.
That said, the radargrams you see in the video have only had a gain and bandpass applied. This is a matter of choice but I prefer to look at the minimally processed radargrams most of the time.
Thanks for this masterclass. More of this on other techniques please!
Thanks for the detailed explanation of the equipment and data interpretation. Something that is missed from the show as it shows how much the science supports the diggers choices.
A big thank you Jimmy, that was absolutely fascinating and very informative. Well presented too. As a next step it would be great to get the GPR and magnetometry data and air photos all layered together in the same way so we could see what that reveals. Any chance of that? Go on, buy Stewart a pint :-)
Very interesting. Thank you.
Do you think that a maser would work for GPR purposes? Given the narrow beam produced, a portable one could be slung under a drone, to permit rapid GPR.
That may be optimistic because I am assuming that the reflected signal could be readily detected above the ground. That could true with a maser however, with its precise frequency operation.
Lasers could also be used for 'field scanning' purposes, I believe. Much quicker than walking.
How much is the result influenced by moisture? Is it better when it is dry or when the soil is wetter?
It looks like, despite the GPS, the terrain is covered in parallel, straight paths. What is the reason for this? Can the result be improved if (especially linear features) are surveyed from different angles?
The wheel should be compact, but can the result be improved if (more) receivers record data at a distance from the transmitter? Like with sonar, for example.
Is a single frequency used or are there different frequencies depending on the type of bottom and targets? I suppose this would have an impact on penetration depth and resolution.
The moisture question is tricky - it depends so much on the method in use and the target you're going after. For example, resistance survey (with the "electric walkingframe") can struggle if it's very dry or very wet as you lose contrast between the archaeology and surrounding soils; you want 'Goldilocks' weather for that to work at its best. For GPR, generally speaking, wetter is worse as the ground conductivity goes up and the signal is attenuated quicker so you lose penetration. The straight‐path survey mode is really to ensure efficient and even coverage but on arable land it is also a practical consideration: going parallel to dominant plough-direction allows us to minimise the harsh impact of the near-surface agricultural disturbance and going across the plough-lines can be really uncomfortable for the operator and the kit as you bounce over the ridges and ruts. These multichannel systems are designed with antenna centres so close that the improvement gained from also running in another direction doesn't normally warrant the additional time and effort. And you can set-up a system to use a different frequency to improve either resolution or depth but for the majority of archaeology the sweetspot tends to be around the 500MHz mark. There are multifrequency systems available too but there are pros and cons to both approaches. There probably isn't much advantage to shooting different locations as, again, it would require more complex processing to correct for the various offsets (rather than effectively treating send and receive as being at the same location) so may not pass the cost/benefit analysis. But who knows what the future holds for our tech...? 🙂
Are any of the filters (I saw bandpass) or processing you use similar to what is done for seismic processing. I guess you are almost doing seismic recording just at shallow depths with finer detail (I'm from both a Seismic and Archaeology background but never really worked with the acquisition sides of either)
Yes, very similar in principle except of course we are operating in the electromagnetic realm and detecting those contrasts rather than changes in density/elasticity. So the processing steps and filters used are often the same but adapted for that fundamental difference.
I would love to see a NEW AND IMPROVED geophys of King Alfred's Atheleny Abbey (the first episode of Time Team).
How do you now that it's demolition rubble (before digging) rather than walls? Is it because of the "fuzzy borders" on the north and east walls?
Can you put the GPR and the magnatomitor in the same kit or does the mag. interfere with the GPR?
Doubt you can mount the magnetometer and the GPR on the same survey equipment. The magnetometer equipment has to have a very low magnetic signature itself, the magnetic field it's measuring is relatively week. The GPR kit has significant amounts of electronic equipment, particularly transmitters, which will have significant magnetic fields. If the results contain sufficiently accurate position data, the two data sets can probably be overlaid accurately post capture though.
There are groups who have attempted this but, as Harry says, you need a good offset between the 2 sets of hardware otherwise the mag data becomes unusable.
@Jimmy Adcock: A question to Jimmy as a *theoretical* ;-) physicist with a PhD and 20 years modelling experience. Would it not help to do the field from left to right and then perpendicular from top to bottom and then merge both sets of scans to get a better noise-signal ratio. It should be possible to precisely match the location of both sets if you put at every 10 meters or so, an object in the ground emmiting a very strong signal which u can use to merge the sets in space? I am just curious... Best wishes from Luxembourg, Tom
These multichannel systems are designed to be truly 3D which means we space the antenna pairs within 1/4 of the dominant wavelength and collect data equally inline and crossline. Then we can construct the radargrams in any orientation we wish. Arguably in an ideal world there maybe some slight improvements to be had by repeating in another orientation (and we can have very accurate absolute positioning available so little need for ground referencing) but the reality is that (when we review what is found and missed in previous datasets) for archaeological targets it's very unlikely to provide huge gains or alter your final interpretation and doesn't justify doubling survey times. Specifically on this site, collecting a dataset across the dominant plough direction would most likely introduce more noise.
@@jimmyadcockABEM thx for the quick reply. That's what I thought, theoretically it should improve noise-signal but empirically could just be minimally plus other issues. OK, u kind of do already both directions because u have a 3D sensoring device. So there is a preferred plowing direction for centuries? I guess the direction is where they can plow the longest in one go so you minimize the turns? I am not a farmer. Can it change? Do some fields have a strong preference for directions and others are either way? I would have thought that the dominant plough direction would generate certain types of correlated signals that can be filtered out? Also, if you had a method to quantitatively distinguish between plough direction and the other, you could find out how deep the plough affected the ground and which is virgin ground by doing both directions? wld this help archeologists? sorry just brainstorming...
@@tweidig I'm no expert on arable (probably more of a Stewart question) but it's a combination of slope and space. You'd want to do the longest runs possible most of the time but you also want to avoid ploughing across steeper slopes. Generally on sloping sites the agriculture is in the same direction from evidence of medieval ridge and furrow through to modern mechanical ploughing. On flatter sites you might see different directions. But the problem with attempting to define a filtering algorithm is that, over the years, the ploughing doesn't quite line up both in terms of spacing and orientation. And the 'noise' we record from the agriculture is not just derived from the present regime but also historic ploughing which has caused changes to the structure and composition of soils. All part of the 'fun' 😀
Hi, have ALWAYS loved Time Team, Messrs Gator and Ainsworth were always seen as USEFUL by Phil Harding but, I "Side" with Phil... "Just dig a bloody hole" lol !!!!
looks like a landslide happpend in the one lower area at some point
Nice 'cleaned up' images compared to the original episodes. A terribly botched excavation but good geophys work that was misinterpreted at the time.
👍
❤
✌️
Informative, but stop waving your hands around in front of the camera because it's affecting the focus and lighting
Is "orientate" a word? I know "orientated" isn't.
If we wanted someone giving a lecture on blah blah blah we would have gone to Uni but we want to see what you found on the dig, eg; pottery bones trinkets etc etc.
I'm sure you must realise that you are under no compulsion to watch if you have no interest in what is being said. (And a glance at most of the other comments should show you that you cannot really claim to speak for what "we" want.)
Personally I found this presentation one of the most interesting and informative so far. It speaks to the real archaeologists who are interested in the depth of information and findings rather than the superficialities.
Thanks
Thanks
Thanks for the support, Lesley!