Need help to identify anomaly in GPR radargram. Void or not!....

[ThomasJ]

Hello. I would like to know the forum opinion on the below radargram, if it shows a void or not. The numbers above are distance in meters, and the vertical scale is 0 to 30 meters. The profile was created with a MALÅ GX 160 Mhz (range about 16 meters max, before noise). My guess for the soil is packed earth mixed with small rocks. Or pure bedrock.

We scanned as we are looking for archaeological anomalies. We did not just scan at random but information have lead us to this place. We are looking for a "back filled" cavity. I'm not a pro radargram reader, but does it not look like "settled" earth have left a cavity at the roof section of a back filled larger cavity? Maybe water filled? This "cavity" is located at about 10 to 12 meters depth?

I would really appreciate input from people with experience reading radargrams. If not a void, then what is it?

 

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[Doubter in MD]

I'm not your guy. It looks like a picture of a pond to me.

 

[ThomasJ]

ok.. do you mean that the black and white striped area in the middle is a water filled cavity? Or what do you mean with pond?

 

[Doubter in MD]

Sorry. I meant it looks like a pond. Ripples on the top of water. I was trying to be funny. I am sure someone with some expertise will weigh in.

 

[Seden]

Sorry, I can only interpret Seismic. Good luck!

 

[jwatkins]

What part of the country was this in? GPR can really on see down 5 feet or so....There is no way it can see 30 meters!

 

[gmradar]

Is your antenna shielded or not? This may be something from above if your antenna is un-shielded.

 

[Red James Cash]

[/QUOTE] What part of the country was this in? GPR can really on see down 5 feet or so....There is no way it can see 30 meters[/QUOTE]

Seems to me that it would depend on the material your signal is going through.Ive read heavy clay with salt present is a tough one,sandy soil is the best for signal penetration.Up to 30 feet for pipes laying in sandy soil.depending on your equipment.


looks like you might have a cave,chamber.comparing yours to other read outs.

 

[AUVnav]

Do you have the entire image, not cutoff?

 

[gmradar]

I still believe this is data from unshielded antenna so what you see is mainly something just above you.

 

[jwatkins]

What part of the country was this in? GPR can really on see down 5 feet or so....There is no way it can see 30 meters[/QUOTE]

Seems to me that it would depend on the material your signal is going through.Ive read heavy clay with salt present is a tough one,sandy soil is the best for signal penetration.Up to 30 feet for pipes laying in sandy soil.depending on your equipment.


looks like you might have a cave,chamber.comparing yours to other read outs.[/QUOTE]

Yes you are correct Red James. Meant to say something more like the subsurface material can effect how far the signal will move. I am down in the clay and we can't see far at all through it with the gpr

 

[gollum]

jwatkins,

Also frequency of antenna will determine depth of readings and clarity of readings. Just like in metal detector 101, a lower frequency will punch deeper at the expense of clarity of the reading. A higher frequency antenna will show better clarity, but won't punch down as deep.

A smaller (read: Hand held) GPR that is actually very good on shallower targets, and very portable is the GSSI Profiler:



Only good to about 8 feet, but do you really want to dig a hole deeper than eight feet deep? HAHAHA

Mike