AMSTRAD PPC 640S User manual

AMSTRAD PPC 640S User manual
Geophysical Instrumentation in Bradford
- Past and Present
by Roger Walker
© Copyright Geoscan Research 2006
Structure of Talk
• This talk is a whirlwind tour of the wide range of geophysical instrumentation used and developed
“In Bradford”, with a special emphasis towards those that Arnold has been involved with
• Includes the six PhDs in geophysical instrumentation admirably overseen by Arnold Aspinall
• References to papers that Arnold has been involved with are given at the bottom of some slides
• By “In Bradford” we mean :
The University Department
Geoscan Research
GSB Prospection
………………….and areas of collaboration between them
• Essentially a good excuse to show as many interesting (and embarrassing ?) photos as possible !
• A time-line is shown of the right hand side as a guide to where we are in our time travelling
1968
1970
1980
1990
GSB Prospection
University
2000
N
2006
Geoscan Research
1 mile
Geophysical Instrumentation in Bradford - Past and Present
2
Early Days
• “Geophysical prospection methods in archaeology” starts in c1968
• Located in the Physics Department, Main Building then moved to Horton Building c 1975
1968
1970
1980
1990
Censored !
2000
2006
Geophysical Instrumentation in Bradford - Past and Present
3
Induced Polarization and Resistance Methods 1968 - 1970
John Lynam, “Techniques of geophysical prospection as
applied to near surface structure determination” 1970
1968
1970
• Four probe system – two current probes, two potential probes
• Examined Induced Polarisation in the time domain
• Non-polarizing probes made from Tufnol and conducting gel
• Measured IP and electrical resistance
• Slow measurement technique
1980
1990
2000
Block diagram
Tufnol probe
Typical results
2006
A.Aspinall, J.T.Lynam “Induced polarization as a technique for archaeological surveying “ 1968
Geophysical Instrumentation in Bradford - Past and Present
4
Resistance Methods and the Two Electrode Configuration
• Many different arrangements of four probes possible for
electrical resistance measurements
• Prior to this time electrical resistance arrays typically used were :
Wenner, Double Dipole and Square array
• John Lynam developed the idea, application and theory of
the Twin Electrode Array in his thesis
• Four probes but only two probes move
• Independent of probe orientation
• Independent of probe insertion depth
• Single peaks only over typical targets
1968
1970
1980
1990
2000
2006
A.Aspinall, J,T.Lynam “An induced polarization instrument for the detection of near surface
features“ 1970
Geophysical Instrumentation in Bradford - Past and Present
5
“Bradphys” Resistance Meter 1970
1968
1970
1980
• Based on instrumentation from John Lynam’s thesis
• Meter weight 4.8 Kg plus frame
• Range 1000 ohms to 0.01 ohms
• Constant current 0-10 mA RMS at 200V
• Frequency 128 Hz
• Maximum contact resistance 40 Kohm
• High Input impedance synchronous voltmeter
• Back-off facility to speed up readings
• Digital version followed known as the “DigiPhys”
• Electric shock common in wet weather !
1990
2000
2006
A.Aspinall, K.Pickard “A direct reading resistance meter”, 1971
Geophysical Instrumentation in Bradford - Past and Present
6
Survey Methods
• Area surveys typically used sampling intervals of 1m
• A mesh of 100 x 1m grids was laid out as a guide
• Mesh made from linked washing lines – tangling was a curse !
• No data loggers – all readings written down on gridded sheets of paper
• Other probe arrays were explored for special applications eg 3 probe
1968
1970
1980
Three probe array at York
1990
2000
2006
John Samuels at Barnetby Top
Jenny Pearson and Jim Pocok
Geophysical Instrumentation in Bradford - Past and Present
Dave Brinklow with “Dalek” cable drum
7
Early Data Presentation Methods
• Polaroid picture of light box with >100 individual bulbs adjustable for brightness to very plotting levels
• Hand contouring
• Numbers highlight above threshold with colour – good for gradiometers (red positive, blue negative)
• Hand dot-density plots – effective for gradiometer data but very time consuming for resistance data
• eg illustration on the right took two evenings to plot – must get plotting levels right first time !
1968
1970
1980
1990
2000
2006
Geophysical Instrumentation in Bradford - Past and Present
8
Cogges Manor Garden Survey
• An early example of garden archaeology and geophysics – one of Arnold’s current pet persuits
• Garden paths show clearly plus some evidence of earlier building phases
• Overwhelming memory of Pavlov type electric shock therapy in the wet long grass !
• Not surprising when you look at what 10 mA RMS current can do……..
1968
1970
1980
1990
2000
2006
Geophysical Instrumentation in Bradford - Past and Present
9
Plessey Gradiometer c 1971
• Fluxgate Gradiometer
• 1m sensor separation
• Analogue meter display
• No data logger
• Very heavy – 6 Kg
1968
1970
1980
1990
Arnold Aspinall
Gill Bussell and Dave
Philpot, F.V., 1973 “An improved fluxgate magnetometer for archaeological prospecting”
Pros. Arch., 7-8, 99-106
Geophysical Instrumentation in Bradford - Past and Present
2000
2006
10
Littlemoor Gradiometer c1972
• Fluxgate Gradiometer
• 1m sensor separation
• Bar graph meter display
• No data logger
• Heavy – 4.5 Kg
1968
1970
1980
1990
Jim Pocock and student
2000
2006
Arnold Aspinall
Geophysical Instrumentation in Bradford - Past and Present
11
Philpot AM01, DM01, DM02 c1973-c1986
• Fluxgate Gradiometer
• 0.5m sensor separation
• Introduced with analogue display version as AM01
• Department acquired digital display version DM01
in about 1977
• Lightweight – 1.6 Kg
• No data logger
• Computerised plotting system producing traces
1968
1970
1980
Note the obligatory well cut smart suit for field survey !
1990
2000
Heathcote, C, Aspinall, A. 1981 “Some
aspects of the use of fluxgate
magnetometers (gradiometers) in
geophysical prospection in archaeology”,
Revue D’Archeometrie, No.5, Volume II
Geophysical Instrumentation in Bradford - Past and Present
2006
12
Paddock Hill Survey 1972-1982 +
1968
1970
1980
1990
2000
• Surveyed using a combination of Littlemoor and Philpot DM02 fluxgate gradiometers
• Start of large landscape surveys
• Data recorded on paper then hand dot-density plots produced
• Jim was so keen he was even known to have spent some holidays there !
• Arnold and Jim accompanied by Priscilla and Gaye as data recorders…….
• Competitions to see who recorded the most 20m grids in a day !
Geophysical Instrumentation in Bradford - Past and Present
2006
13
Brough of Birsay Survey, Orkney 1975
• Survey of Ancient Monuments ecclesiastical site with Plessey fluxgate gradiometer
• First met John Gater here – though the stampeding cows made it touch and go if we ever left Orkney alive !
• Igneous nature of Orkney posed problems though not as much as the causeway !
• We left the island via a flooding causeway each evening at the last possible moment, water up to our thighs,
carrying a very expensive departmental gradiometer. I had nightmare visions of slipping and the wooden
case the gradiometer was in floating off to sea !
The director of operations was a
certain John Hunter……..
1968
1970
1980
1990
2000
2006
Geophysical Instrumentation in Bradford - Past and Present
14
Bartington Magnetic Susceptibility Meter and Glenluce
• The department also had a Bartington magnetic susceptibility meter
• Seen here taking measurements at Glenluce sand dunes in the Scottish Borders
• An hospitable site : desert like, adders and unexploded ordnance on a military firing range !
• But very memorable as I am sure Arnold would agree. Desert sickness obviously got to some of us ……
1968
1970
1980
1990
2000
2006
Arnold, Rob Poulton, Dennis Mott
Geophysical Instrumentation in Bradford - Past and Present
15
Electromagnetic Methods 1973-1976
Roger Walker, “An investigation into the application of
electromagnetic methods of geophysical surveying to
shallow depths” 1980
1968
1970
• In-phase and quadrature measurements for magnetic and
conductive responses at 12.5 KHz
• Horizontal co-planar coils, 3rd coil to null coupling
1980
1990
2000
EM Real and Gradiometer, Thwing
2006
Geophysical Instrumentation in Bradford - Past and Present
16
Magnetic Susceptibility Bridge 1973-1976
• Department had a bridge that measured just In-phase only
• New bridge design conceived as a pilot study towards an
improved EM instrument
• In-phase and quadrature measurements for magnetic susceptibility
and magnetic viscosity parameters of soil samples
1968
1970
1980
1990
2000
2006
Geophysical Instrumentation in Bradford - Past and Present
17
In-situ Measurement of Magnetic Susceptibility 1973-1976
• Profiles of soil section magnetic susceptibility
• Coil system moved down soil section at 2cm intervals
• Existing EM electronics used with new coil design
• Over-lapping coils for zero coupling, 12.5 KHz
1968
1970
1980
1990
Field tests at York Archaeological Trust site
2000
2006
Geophysical Instrumentation in Bradford - Past and Present
18
Program “Dotty” – forerunner to Geoplot 1975
• Computer processing well established (Linnington 1968)
• Only main frame computers generally available at this time
• Dot-density plots described by Scollar in 1966
• Program “Dotty” written on Hewlett Packard HP2116B :
• 16K memory, 16 bit processor, paper tape reader
• Tektronix thermal hard copy
• Data punched in on paper tapes at a teletype terminal
• Plotting parameters : Minimum, Maximum, Contrast
• Histogram output
1968
1970
1980
1990
2000
2006
Geophysical Instrumentation in Bradford - Past and Present
19
Pulse Induction and Magnetic Methods 1977-1980
Colin Heathcote, “Applications of magnetic and pulsed induction
methods to geophysical prospection at shallow depths” 1983
1968
1970
• Pulse Induction methods provided a measure of the magnetic
viscosity component of soils
• Fluxgate sensor design explored
• A comprehensive library of magnetometer response curves derived
1980
1990
Magnetic response curves
2000
2006
Colin and Littlemoor Gradiometer
PIM system MK II and Arnold Aspinall
Geophysical Instrumentation in Bradford - Past and Present
20
Proton Magnetometer 1977
• Two sensors in vertical gradiometer configuration
• Developed by Geoff Spinks
• Tests performed at Scorton, Catterick, May-June 1977
• Sample interval 1m
1968
1970
1980
1990
Data entry form for submitting data to the computing centre
2000
Date entry form for use in the field
Geophysical Instrumentation in Bradford - Past and Present
2006
21
Technical Staff – Past and Present
Geophysics and instrumentation development at Bradford was only made
possible with the support and enthusiasm of the Universities technical staff :
Keith Pickard
Dennis Mott
Dennis Ives
Jim Pocock
John Crummett
Geoff Spinks
Peter Dale
Stuart Fox
1968
1970
1980
1990
2000
2006
Geophysical Instrumentation in Bradford - Past and Present
22
Some familiar faces from the past……
Geophysical Instrumentation in Bradford - Past and Present
23
RM4 Resistance Meter and PA1 Probe Array 1984
1968
1970
1980
1990
• Very light and compact – 0.9 Kg, 160 x 85 x 85 mm
• Range 2000 ohms to 0.01 ohms
• Constant current 1mA peak-peak at 40V
• Maximum contact resistance 40Kohm
• Current chosen to avoid electric shocks
• PA1 0.5m Twin Electrode Array
• Corny first advert !
Geophysical Instrumentation in Bradford - Past and Present
2000
2006
24
DL10 Data Logger for RM4 1985
1968
1970
1980
1990
• 1000 reading data logger
• Elimination of paper recording allowed one person surveys
• Auto-logging when Twin probes inserted into the ground
• Logging commands : Dummy, Finish Line, Image Line
• No LCD display – survey tracking with audible sounds :
“beeps”, “chirps” and “warbles” !
• Analogue input for use with other instruments
• Needed a portable computer in the field, ie Epson HX20
• Download every two 20m square grids
• Weight 0.7 Kg
Geophysical Instrumentation in Bradford - Past and Present
2000
2006
25
Geoplot for Epson HX20 portable 1985
Mike Kelly – 1st use of HX20
Geoplot Output
1968
1970
1980
1990
Epson HX20 Computer :
• 16K memory and battery operated
• Built-in micro-cassette audio tape drive for data storage
• Built-in dot-matrix “till-roll” printer for hardcopy output
Mike Kelly and John Haigh made first use of the HX20 in 1984
Geoplot for HX20 followed in 1985
• Data input manually or downloaded from the DL10 logger
• Dot-density plots, trace plots, editing of data (no processing)
• Auto-plots after input from the DL10
Geophysical Instrumentation in Bradford - Past and Present
2000
2006
26
Soutra Medieval Hospital – RM4/DL10 survey 1986
1968
1970
1980
1990
• 84 x 20m x 20m square grids surveyed
• 1m sample interval
• Duration 4.5 days
• Two people surveyed (one pregnant !)
• Blizzard conditions part way
• Geoplot HX20 for on site presentation
• Subsequent processing and presentation
performed with a BBC B computer
Geophysical Instrumentation in Bradford - Past and Present
2000
2006
27
Schlumberger Array 1986
Chris Gaffney, “The Schlumberger array in geophysical
prospection for archaeology” 1990
1968
1970
• Investigation of directional properties of the Schlumberger
array over linear features of width comparable with the
potential probe separation
• Instrumentation, including current booster for the RM4
developed by Peter Dale
1980
1990
Schlumberger response at Tickhill
2000
2006
Chris and Steve Manifold at that
Well known test site, Manor Vale
(Arnold’s back garden !)
Sue Gaffney with RM4, P1 and
current booster on metal plate
Schlumberger probe configuration
Chris from his Dyno-Rod days...
Geophysical Instrumentation in Bradford - Past and Present
28
CB1 Current Booster for RM4 1989
1968
1970
1980
• Increased RM4 output to 10 mA peak to peak, 100 V
• Provided 10 times increase in sensitivity for RM4 when used with
arrays such as the Schlumberger
• Developed as a result of Chris Gaffney’s and Peter Dale work
• RM4+CB1 combination a pre-cursor to the RM15 resistance meter
1990
2000
2006
Geophysical Instrumentation in Bradford - Past and Present
29
FM9, FM18, FM36 Fluxgate Gradiometer Series 1987
• Fluxgate Gradiometer
• 0.5m sensor separation
• Digital display plus bar graph display
• FM9 : no data logger
• FM18 : built-in data logger 4000 readings
• FM36 : built-in data logger 16000 readings
• Hand-held trigger device for logging readings
• Survey tracking and commands like DL10 but displayed
• Lightweight – 2.35 Kg
1968
1970
1980
1990
2000
2006
Alan Walker demonstrating the FM36
Geophysical Instrumentation in Bradford - Past and Present
30
ST1 Sample Trigger for FM series 1987
• Generates trigger pulses for FM18 and FM36
• Enabled rapid collection of detailed data sets at :
1, 2, 4, 8 or 16 sample per metre
• Variable speed metronome to guide walking position
• Powered by FM18 or FM36
1968
1970
1980
1990
2000
2006
Geophysical Instrumentation in Bradford - Past and Present
31
Grove Cottage Survey (with John Gater of GSB) 1986
• First survey with an FM series gradiometer
• Right hand half surveyed with an FM9 and DL10 data logger
• Left hand half surveyed with a Philpot AM01 and DL10 data logger
• RM4 / DL10 complimentary resistance survey done at the same time
1968
1970
1980
1990
2000
Resistance data
2006
Gradiometer data
Geophysical Instrumentation in Bradford - Past and Present
32
Examples of FM18/36 in use
Shetland ?
Adel 1994
Case customisation by Tomek Herbich !
Geophysical Instrumentation in Bradford - Past and Present
33
Geoplot 1.0 for IBM Compatible DOS computers 1989
1968
1970
1980
1990
Amstrad PPC portable computer
Portable IBM Compatible DOS computers introduced :
• 640K memory and battery operated
• Built-in floppy disks for data storage
• More pixels on the screen – but only 4 shades of grey
• Large size dot-density and trace plot printouts possible
2000
2006
Geophysical Instrumentation in Bradford - Past and Present
34
Induced Polarization Methods Revisited c1986 - 1989
Sue Ovenden, “Frequency mode induced polarization studies
for geophysical exploration in archaeology” 1990
1968
1970
• Examined Induced Polarisation in the frequency domain
• Probe polarization problems avoided in the frequency domain
• Instrumentation developed by Peter Dale
1980
1990
2000
Model studies
Geophysical Instrumentation in Bradford - Past and Present
Manor Vale test results
2006
35
Pulse Induction Methods Revisited c 1986 - 1989
John Skinner. Sadly I could not gather information on John’s PhD
work so I’ll use this as a good excuse to sneak in yet another of Arnold
(and John Skinner with Sue Gaffney) !
1968
1970
1980
1990
2000
2006
Geophysical Instrumentation in Bradford - Past and Present
36
RM15 Resistance Meter 1991
1968
1970
1980
RM15 in use at Adel 1994
1990
• Built-in data logger : 3600, 15000 or 30000 readings
• Expansion facilities via external multiplexer
• Very light and compact – 1.5 Kg
• Range 20000 ohms to 0.005 ohms
• Constant current 0.1mA, 1mA or 10 mA peak-peak
• Output Voltage 40V or 100V
• Maximum contact resistance 1 Mohm
• Currents chosen to avoid electric shocks
Geophysical Instrumentation in Bradford - Past and Present
2000
2006
37
PA5 Multi-Probe Array and MPX4 Multiplexer 1991
PA5 Multi-Probe Array
• A “universal” probe array system for the RM4 and RM15
• Standard 0.5m Twin with additional wings and probes
• Twin: 0.25m, 0.5m, 0.75m, 1m, 1.25m, 1.5m, 2m
• Pole-pole
• Gradient
• Wenner
• Double-Dipole
• Square 0.75m
1968
1970
1980
MPX4 Multiplexer
• Switch for manual multiplexing of up to 4 Twin spacings
• Configure Twin, Wenner, Double-Dipole, Square arrays
1990
2000
2006
MPX4 Multiplexer
Geophysical Instrumentation in Bradford - Past and Present
38
Things don’t always go right………
Arnold and Jim hang their heads in despair as John vainly looks for a reading……
Geophysical Instrumentation in Bradford - Past and Present
39
TRM Measurements in the Field, Shetland c1992
Device built by Peter Dale, used by John Crummet and Arnold for TRM measurements
Part of Steve Dockrill’s excavations at Trowie Loch, Shetland
Aim was to determine if stones in burnt mounds were “fired” in situ or heated individually
Device clamped to the end of a Littlemoor gradiometer and stone rotated in 2 directions
Results inconclusive since most rocks in Shetland were igneous !
1968
1970
However I’m told Arnold will remember the trip not for the physics but for Mrs Blanches MEGA meals.
1980
1990
2000
2006
John Crummett surveying old croft dwellings, South Nesting, Shetland
Geophysical Instrumentation in Bradford - Past and Present
40
Geoplot 2.0 for DOS 1992
• Colour and full range grey scale plots introduced
• Large range of processing and analysis functions
• Improved print out quality
1968
1970
1980
1990
2000
2006
Geophysical Instrumentation in Bradford - Past and Present
41
Birth of Archaeological Prospection Journal 1994
• 1994 sees the landmark launch of “Archaeological Prospection”
• With Arnold Aspinall and Mark Pollard as joint editors
1968
1970
1980
1990
2000
2006
Geophysical Instrumentation in Bradford - Past and Present
42
MPX15 Multiplexer for RM15 1995
• Automated multiplexing with the PA5 probe array
• Offers a wide range of configurations eg:
Parallel Twin for greater speed or more detail
Multiple Twin for depth investigations eg pseudosections
Simultaneous configurations eg Wenner alpha and beta
• User programmable
• Up to 8 user defined programs
• Up to 8 sequences per program
• Auto-Logs up to 4 readings per second
1968
1970
1980
1990
2000
2006
Geophysical Instrumentation in Bradford - Past and Present
43
Wroxeter Survey June 1996
• Multiplexed Twin 0.25m to 1.5m
• Also Wenner and Double-Dipole
• Stacked pseudo-sections generated
• Enables broader understanding
• Narrower Twin spacing: near surface
cellular structures, internal partitions
• Wider Twin spacing : substantial
underlying features and colonade
1968
1970
1980
1990
2000
2006
40 m
Geophysical Instrumentation in Bradford - Past and Present
44
Geoplot 3.0 for Windows 2000
1968
1970
1980
1990
2000
2006
Geophysical Instrumentation in Bradford - Past and Present
45
FM256 Fluxgate Gradiometer System 2002
FM256 Single Instrument
• Integral data logger, 256000 readings, 15 min. full download
• Integral sample trigger
• Independent sample and traverse intervals : 1 to 16 samples/m
• LCD backlight and contrast adjustment for poor light conditions
• NiMH battery, 21 hour operation, 4hr fast charge (LED status)
Survey over Romano-British site, Towton
1968
1970
Dual Gradiometer System
• Use two instruments for double speed / increased density surveys
• Master/slave system accepts FM18/36 or FM256 slave
• Interleaving gives 0.5m or 0.25m traverse intervals
• Open frame gives rapid operator turn-around for zig-zag surveys
• Integral master start/stop controls on frame
1980
1990
2000
2006
Geophysical Instrumentation in Bradford - Past and Present
N
20 m
46
Moresby Roman Fort 2002 / 2004
• Dual FM256 fluxgate gradiometer survey, 4 samples / m
• Area 3.1 h, consisting of 78 20mx20m grids
• East side is heavily disturbed by a Victorian cemetery and churchyard
• A considerable wealth of features survive including rampart, outer
ditches, internal buildings or barracks, entrance or gatehouse to the
south, possible bath-house outside the fort also to the south
1968
1970
1980
1990
N
2000
-5 nT
+5 nT
2006
40 m
Geophysical Instrumentation in Bradford - Past and Present
47
North Acres in Saxton, Towton Battlefield 2002
1968
Comparison of FM256 fluxgate gradiometer survey with
previous metal detector survey over arrow head spread.
The absence of targets with +/- 2.5 nT thresholds
compares well with the greatest concentration of metal
detector finds but indicates a few remaining possible
arrows on the perimeter.
1970
N
Grey scale –2.5 nT to + 2.5 nT
Significant +ve @ -ve targets
1980
Metal detector finds and location
1990
Threshold +/- 1.5 nT
Threshold +/- 2.0 nT
Threshold +/- 2.5 nT
2000
2006
Taking a well earned rest !
Geophysical Instrumentation in Bradford - Past and Present
48
Taking a well earned rest, Towton Battlefield 2002
1968
1970
1980
1990
2000
2006
4 sandwiches
Geophysical Instrumentation in Bradford - Past and Present
49
Start of development of Wheeled Square Array 2003
• 0.75m Square array
• Four spiked wheels
• 12 connected spikes per wheel
• Alpha configuration only
• Time based sample triggering
• Speed 1 –2 seconds / m
• Sample interval 0.25m
Early results over
a repeated 10m line
Wheeled Square Array in use over a
very stubbly field at Towton Battlefield
1968
1970
1980
1990
Tim Sutherland wishing he had
never suggested the idea !
2000
Alpha:
A
2006
B
M
N
Geophysical Instrumentation in Bradford - Past and Present
20 m
Leonardo Da Vinci !
50
High Resolution Surveys, Jarlshof, Shetland 2003
• Comparative high resolution wheeled resistance and gradiometer surveys
• Prehistoric, norse and medieval settlement at Jarlshof, Shetland.
• Dual FM256 fluxgate gradiometer with sample interval = 0.125m and traverse interval = 0.25m
• Prototype Square array in Alpha mode with sample interval = 0.25m and traverse interval = 0.5m
• The survey area was only 13m x 8m but reveals considerable detail
1968
1970
1980
1990
2000
All went well for Kath and myself though
Steve Dockrill had trouble with the natives……
Geophysical Instrumentation in Bradford - Past and Present
2006
51
Square array investigations at the University c2002 - 2004
Whilst Geoscan worked on the Square array, MA students at the University were also doing
their own investigations…..
1968
1970
1980
1990
2000
Tom Sparrow using the Square array at Adel
Mary Saunders using the Square array on a
Time Team programme
2006
A.Aspinall, M.K.Saunders “Experiments with the Square Array”, 2005. AP 12, 115-129
Geophysical Instrumentation in Bradford - Past and Present
52
Drumlanrig Castle (with GSB and Time Team) 2004
Square Array Alpha data
A suspected Roman fort in
the grounds of Drumlanrig
Castle was surveyed with a
production prototype 0.75m
wheeled square array
system and comparative
0.5m Twin array. Alpha
data was collected at 4
samples/m whilst Twin was
collected at 1 sample / m.
Alpha survey speed was
approximately 7.5 minutes
per grid.
1970
1980
1990
Internal roadways of the fort
are clearly visible, along
with other fine detail which
is not visible in the Twin
data.
Alpha:
A
B
M
1968
0.5m Twin Array Data
N
2000
2006
N
40 m
Geophysical Instrumentation in Bradford - Past and Present
53
Littlemoor Castle Multiplexed Alpha/Beta Survey 2004
• New enclosed wheel design with distance encoder for triggering
• Multiplexed Alpha and Beta measurements
• 4 samples / m at a speed of 1 second / m
• Survey over filled in ornamental Victorian pond below Castle
• Complimentary FM256 gradiometer survey
• Alpha and Beta data is directional and complimentary (eg field drains)
Alpha Data (20m x 40m)
Beta Data (20m x 40m)
1968
1970
1980
N
1990
Alpha+Beta Data
HPF Alpha+Beta Data
Gradiometer Data
Alpha: A
M
B
N
2000
Beta:
B
A
20 m
N
M
2006
• A big thank you to Lew Somers seen here in action at Littlemoor !
Geophysical Instrumentation in Bradford - Past and Present
54
Dunkirt Barn Survey (with English Heritage) 2004
• Late Iron Age site with associated Roman villa in Hampshire
• Chalk, recent ploughing, straw stubble, very large flints
• 0.75m Square array, 2 samples / m, multiplexed alpha and beta
• 0.5m Twin array, 1 sample / m
• Very wet conditions built up “wattle + daub” on the wheels !
• Despite this foundations of part of villa complex were revealed
• Excellent correspondence between Square and Twin data sets
1968
1970
1980
Square Array Data
Twin Array Data
1990
2000
N
A slight problem with mud !
30 m
Geophysical Instrumentation in Bradford - Past and Present
2006
(since resolved)
55
PA20 Probe Array 2004
• The PA5 gets a makeover in 2004
• Quick release system for rapid interchange of glass fibre beams
• Lighter in weight than the PA5
1968
1970
1980
1990
2000
2006
Geophysical Instrumentation in Bradford - Past and Present
56
Duncombe Park Garden Survey 2005
• Fluxgate gradiometer is added to wheeled square array
• Simultaneous resistance and magnetic surveys possible
• System becomes the MSP40 – becomes Mobile Sensor Platform
• Survey below reveals probable formal borders of 18 Century gardens
• Strong iron features probably posts for tennis court nets !
Resistance (alpha and beta)
1968
1970
Gradiometer
1980
1990
-15 Ohm
+15 Ohm
-2 nT
+2 nT
2000
N
2006
20 m
Geophysical Instrumentation in Bradford - Past and Present
57
A finally a really big thanks to Arnold Aspinall……..
……..and not forgetting his Manor Vale test site !
John Crummett, Tim Sutherland and Arnold Aspinall at Towton
Geophysical Instrumentation in Bradford - Past and Present
58
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