Parabolic Dish, Long Range Horn and Close Focus Modules. These are names of some accessories offered by some of the ultrasonic instrument manufacturers.
Any of these devices can be used for leak detection, steam traps & leakage, electrical scanning (Radio/TV interference, corona, tracking or arcing), even for mechanical to scan bearings or other devices for anomalies. These are normally either plugged into the ultrasound receiver or connected by a patch cable or other interface.

What is your preception of these devices?

Are you using these devices?

Would you like to know more about these devices?

Jim,

I have used most of these types of sensors. I have measured amplification factor, directivity, and sound Vs distance with several sensors. These sensors improve detection sensitivity (signal to noise ratio) and improve localization. They are essential in many ultrasound measurement applications.

Jim,
What would you use, how, and why to locate radio or tv interference?
Pete

Froto,

The SDT 150 meter can pickup radio signals and interfere with measurements. I have made several ship hatch cover integrity tests, and radio stations (I think AM) came in loud and clear and were higher than the transmitter signals that I was trying to measure. I guess that this does not occur in Europe, because SDT said I was the only one with this problem! The meter is also sensitive to RF inferference around CRT monitors and VFD motor drives. I am skeptical that there is any positive application for detecting radio and TV signals with an ultrasound meter.

Walt

Thanks Walt,
I know the CRT monitors make a squeal as I have heard them with mine. I've never picked up any radio stations, TV or had a need to detect transmitted signals. I thought I was missing something that could be usefull.
Maybe if one of my neighbors had a high powered CB or Ham radio that was interfering with my TV, I could track down the signal to the source and cut his antenna wire! That would be usefull.
Pete

This is where it gets really intresting with todays parabolic reflectors. If the dish is a deep dish and the microphone or receiver is placed close to the rim of the dish the frequencies may be too low (low-frequency)for ultrasound (high frequency). But, when the dish is tuned to a set distance, that is moving the microphone or receiver towards the bottom of dish, certain frequencies are within the TV/Interference range. Anomalies such as corona, tracking and arcing, may be heard by one particular parabolic reflector that another manufacturers will not. I have first hand experience using several different manufactures parabolic reflectors and they all do not pick-up the same signals. Of course this also has to do with the individual make & model receiver. But, I have worked with several utilities to find nuisance or radio/tv interference on everything from 14/4, 13 kv, 230 etc...
I have also found with cable TV that some cable companies will tie into the neutral of say a 14/4 service and steal power to power-up their system. If you have never noticed where ever there is cable tv in an area you will find a box on a shelf either on a power pole or sometimes a vault sitting on the ground near a power pole. This box has a 12 volt battery in it. This splicing into the 14/4 service may help the home owner with cable but can be very annoying to the homeowner who only has an antennae. Radio interference of communications between civil defense workers was another case history I had, where the insulator on a 14/4 pole was bad and it was knocking out the communications for the Civil Defense trucks in north Atlanta during an ice storm the parabolic and Am Receiver enabled me to find this.
If you have a parabolic again know that, not everyones work the same.

quote:

Originally posted by Frotopulper:
Jim,
What would you use, how, and why to locate radio or tv interference?
Pete

Hi Jim,
In the case history of the Civil Defense trucks, was the bad insulator causing arcing or corrona? How does the dish and am reciever work together? I'm no electrician as you know, just trying to understand.
Pete

Typically you can visually see a crack or burned spot on the insulator using binoculars. Corona can be detected using airborne ultrasound on electrical systems of 1 kV or higher. In the case of the insulator it was 14/4. This insulator could no longer insulate. Corona results when the voltage on electrical conductor exceeds the threshold value. Air around the insulator begins to ionize. The ionization creates a disturbance in the air, this disturbance is in the ultrasonic range. Since the discharging ionized air is emitted into the air there is no ground and NO HEAT, so not detectable by Infrared scan (under 240kV). When you hear this nuisance corona, it is typcially heard as you drive down the road and say you have an AM radio station on. The buzzing sound you hear, is typcially the result of corona or ionized gases in the air. This is friction in the air that is ultrasound. Note: If there is a lot of humidity in the air you may have this same condition occurring, but this does not mean you have destructive corona.
If you place your AM reeiver on (radio in car) an off station (no-music or voices) and drive down a road, you all of sudden hear the nuisance corona sound much like a buzzing, frying sound. As you a power pole and the sound disapates or drops off dtamatically stop the vehicle and take the parabolic dish and scan the power pole. Now remeber the parabolic dish is linked to an ultrasonic receiver (SDT, UE, CSi, CTRL, ETC..), when you point the dish in the direction of the power pole you can focus int on the sound. Ultrasound is very directional 1/8 - 5/8" long. Say if you were using just the Am receiver you may hear the sound for miles the highs and lows, using the parabolic dish and receiver however you will only hear the origin of the sound the short=wave signal. An AM Receiver is not needed to find TV Interference it can help. Just point the Airborne ultrasound parabolic receiver at the top of pole or tower, or use one in a substation I am sure you will find an anomaly.

quote:

Originally posted by Frotopulper:
Hi Jim,
In the case history of the Civil Defense trucks, was the bad insulator causing arcing or corrona? How does the dish and am reciever work together? I'm no electrician as you know, just trying to understand.
Pete

This message has been edited. Last edited by: Jim,