The Halt Tape - Humming Sound - What is that noise?

[Guest]

Hi Mitch/Observer,

How can you fully test concept aircraft only in military airspace?

Think about it. There comes a time when the aircraft will need to go out into the public domain and get its certification.

Unfortunately the UK isnt as vast as the USA, The North Sea would be a good testing ground. Minimum casualties if anything goes wrong the only problem is while its over land. If this is over British airspace would not the Emergency Services/Authorities be informed on a need to know only basis.

The Royal Navy/Airforce did a lot of their testing before and during WW2.

How many UK Airfields were operational and secret enough in East Anglia in 1980?

How many use the public coastal areas for training pilots. This has not been deemed too dangerous!

The article that I saw about the vibration tests seemed to indicate that the tests were not only done on the test rig at Orfordness initially, but then the dummys were put in planes and jettioned into the ness/North Sea and recovered for analysis. I was aware that they didnt have live bombs. What I was refering to was in the event of these planes flying low and releasing the dummy. Did the Authorities have procedures in the event of a crash or a stray dummy landing in the village?

The public doesnt always come first in risk assessment and management. In the above cases would it not have more to do with national security and containment?

Regards

Schooner

[Guest]

Hi Admin,

Sounds plausable, given the witnesses did not seem to pick up on the sound it must have been some kind of interference from equipment.

What we need is someone to confirm the electrical operation of one of these USAF Starscopes and whether it could have interfered with the player.

It could however be interference from another source currently unknown?

I'm reading Skycrash at the moment, its enlightening given that Ive read Georgina Brunis book first. I have assumed too much. Theres alot coming through in this book about the military, previous local ufo reports and Bawdsey!

Regards

Schooner

Regards

Schooner

[Guest]

Were they using the starscope at the time (i beleive they used to it to veiw the tree marks) they buzz, more so when/if an infa red light emitter is turned on, especialy the gen 1 instruments which the starscope will have been.

[Observer]

Hi all
Re the questions raised about the starscope and its capabilities.

Back in the 80's, most night vision binoculars and such like were based round the infra red technology of the day. I some how think that a starscope based on that technology would not be able to read heat signatures.
The Pyrovidicon system developed by GEC in more recent times and often used in the search for bodies after buildings collapse uses a heat signature for detection. The optical version still uses a heat signature but through its software package produces a visible night time picture far superior. The military use a system today based round pyrovidicon technology and some off shoots to this technology is classified.

It would be a good idea to ask GEC (They are always willing to answer technical queries) if a Starscope from the 70's/80's and of US manufacture would emmit a humming noise and could it read a heat signature?

Observer

[Guest]

The starscope probably picked up the infa red reflected by the sap in the tree marks

[winkeech]

Hiya,
... I'm newby here, so I have just been browsing some older posts for a better context ... and came across this topic.

Ok, as my profession is largely techno-geek, I found this interesting - not least because I had an patent application on a closely connected issue ... well, doing the opposite actually - making noises like this one appear in tape recordings etc. with a view to helping copy prevention of cd's.

I have had a look at Halt's tape (mp3) on the spectroscope ... and yes there is a definite narrow band tone there of 1.9khz. This is the strange humming noise and sounds a bit like a helicopter gearbox whine. The spectral response of the audio is consistent with a pocket tape recorder/note taker using microcassette tape at SP record speed.

In my professional opinion, this is a modulated audio signal of around 17.1 to 17.2khz that is heterodyning with the sub harmonic of the tape recorder biasing frequency. This is in effect demodulating the HF audio and producing the 1.9khz tone.
At around 17khz, the human ear cannot hear this frequency - but dogs etc can ... most likely hence the animal disturbance.
Note, that the tape recorder cannot record this tone directly either - it is past the recording roll off filter breakpoint (a control engineering detail to maintain sound quality/prevent anti aliasing) but not that of the microphone and the amplifier/ALC circuitry - hence this signal is effectively strobing against the recording bias frequency mixer. This is one of many audio recording generic limitations/exploits that I had to study and engineer on a daily basis.

What is causing it? Hard to say. It could be the object, possibly even some form of Radio frequency breakthrough within the microphone amplifier. If it is actual audio, it is quite a strong signal - as loud as those ultrasonic teenager repellers, if more than a few feet away.

As a test, I have taken a similar recorder to Col Halt's and used it to record the sound from a gen 1+ starscope. It does make a similar, but lower frequency sound ... but the recorder needs to be within inches of the scope to pick it up. The noise from the scope is due to the switched mode inverter that powers the tube. The scope works by having a vacuum tube that is a cascade photon multiplier - in short, light comes in the front of the tube (focused by the lens on the front) and this knocks some electrons off a special cathode grid. A large voltage (400 to 500 volts) is applied to the tube and this voltage accelerates the electrons down to a phosphor screen (green - as it is the highest contrast ratio colour for the human eye) where it knocks out a load more photons thanks to the energy it has picked up ... about 1000 to 1 usually.
The sound is caused by the switched mode invereter quickly ramping the voltage up and down to a preset, which the tube experiences as a small mechanical shock due to its capacitance and rings like a tiny ultrasonic bell ... this is the sound.
It could be that the scope used at the time had a higher frequency inverter and made more of a din, but that would be a design fault if so, as it could give your position away.
Hope this is of help,
Win.

ps. I would post an mp3 of my test sound, but haven't found a way of posting attachments directly here yet.

[AdrianF]

ST

Thanks for posting that. The quality of the original is pretty remarkable. Pro recorder/mic combinations sounded this good back in 1980, but I'm amazed a recording this good came off a lil'ol dictaphone.

I think the hum in between sentences might be caused by some compression applied at some point, boosting the background noise, at least that's what it sounds like to me.

Adrian

[winkeech]

Hiya Adrian/Silvertop,
I did just post a reply, but gremlins seem to have eaten it, so If this appears twice you'll know why!
Ok, I've just joined photbucket so I can give links to the screengrabs I've just made.
It is over twenty years now since I had a chat with Charles Halt ... and so I can sympathise with contributors that were at the incident being expected to have total recall ... here is what I remember. Col Halt did show a pocket recorder to me for a few second and claimed it was the one he used. I have no reason to doubt him - and since he had taken the trouble to bring a cast of a landing mark with him, I think the odds are good. It seemed to be an early, well made olympus pearlcorder - I didn't take much note at the time other than thinking ' ah it's one of those'.
It is my opinion that the tape was previously recorded and that some of the odd noises that occasionally appear (piano music, footsteps etc) are either as a result of tape misalignment at stop/start points or bleedthrough when not completely over written when re-recorded (partial tape hysterysis).
Ok the spectrogram shows a well defined single tone at 1.9khz and a maximm recording bandwidth of around 6khz. This is what you would expect as top end response for a pocket recorder ... pretty good actually.
http://i481.photobucket.com/albums/rr173/winkeech/tone.jpg
The peripheral sound levels seem remarkably high for a simple omni mic - I don't know the provenance of the tape, but it looks to me as though the audio was run through a compressor and a noise filter prior to mp3 compression. That would make sense.

I then made a recording of the sound made by a gen 1 plus scope - recorded at a distance of half to one inch away from the scope body. I have uploaded it here on youtube:
http://uk.youtube.com/watch?v=10c7BEEG_cA
as you can hear it has a much wider sound spectrum than the single tone on Halt's recording and generaly sounds lower ... but there is a single tone peak at around 3khz, which can be seen on the spectrogram ... which is here at:
http://i481.photobucket.com/albums/rr173/winkeech/experiment.jpg
As we can see, the overall frequency response of this recorder is identical to Halt's original (around 6 khz top end) and so it looks as though he really did record it on his pocket recorder ... or went to a lot of trouble and fine detail in a studio afterwards ... for me, everything points to it being as he described - nothing I see here contradicts his assertation.
Hope that is of some help,
and I hope the reply posts correctly this time!
best wishes, Win.

[Observer]

Can some one tell me in simple terms please [because all this technical jargon is way over my head] what relevance this humming sound is to the alleged Rendlesham Forest Incident.

Obs

[puddlepirate]

Hi Winkeech

Thanks for the info.... am I right in thinking that your technical analysis confirms that the hum was caused by the tape recorder being in close proximity to an active starscope and therefore the tape was almost certainly recorded in the forest using a standard service issue dictaphone loaded with a minature tape cassette and not something knocked up in an office or studio on a reel to reel machine?

If so and if the mike was sensitive enough to pick up sound not audible to the human ear, would spectrum analysis of the tape reveal other background noise from the forest... stuff that might have been some distance away, e.g. persons moving around, forest creatures and possibly also low frequency EM type hum and so forth?

[winkeech]

Hiya PP,
I think my last post hopefully covers that ... but to re-iterate. A starscope could cause that sound, but the recorder would have to be right next to it. It seems something else was most likely making that sound. The people present would not have been able to hear it ... but it may have affected them without knowing. The animals could plainly hear it. This is infact similar to my first ufo sighting back in 1976 ... it was only the dogs in the village suddenly barking in unison that alerted me. The sound was artificial. Halt did use his pocket recorder as he claimed and this was not contrived on a studio reel to reel recorder ... the frequency response and roll off rate are wrong for that. They are correct for a pocket recorder though. Hope of use, Win.

[winkeech]

Sorry Puddlepirate,
I didn't answer one of your questions ... Is there other sound that can be identified/extracted?

well, I haven't found any as yet - elf would be below the mic's bottom response but an overtone may affect the alc response ... haven't seen any evidence of that, so I would say that it isn't present.

Could other sound be brought out ... possibly, using digtal filtering it is theoreticaly possible to reduce the voice level quite a bit and bring up other sound components ... I may give it a spin if I get time, but I would say that I haven't seen any indications that it is there ... and the poor little pocket recorder has done a sterling job as it is - I don't think we can expect much more performance from its recording, best wishes, Win.

[puddlepirate]

Thanks, Win.... that's cool. Hoping to find evidence of anything else, particularly low frequency, was a long shot but worth a try. What I had hoped for was something with a sound signature that could be linked to radar emissions and the fogged photos discussed on a different thread.....

[winkeech]

Hiya Puddlepirate,
I've run a digi filter to see if I can find any LF sound modulating the bottom of the recorder's freq response ... nope - can't find any evidence of this - doesn't neccesarily mean it's not there, just that it would be so far below the bottom response freq of this type of recorder that it hasn't been able to register even a harmonic overtone ... sorry, just can't get a sniff. Righty ho - back to work,
catch you later,
Win.

[puddlepirate]

Hi Win

Many thanks for trying. Much appreciated.

[redsocks]

So what are you guys trying to prove here? that Halt didnt record events later in a studio? The troops were there the lightalls were there,he was there going through the forest with he's tape recorder.Does that mean that they must have been following a UFO? I dont think so.Like I have said in the past, at night start at where BTDT states where the troops were out side of road near east gate go through the forest as Halt etc did,come out at the edge of the farmers field where they did and between A and B is a straight line to the Orford lighthouse,do this I have done it you will see.now between these two points somebody can record what they want,what they think they may be seeing.

Redsocks

[Observer]

Redsocks

Ian Ridpath may still be vindicated with his light house theory.
Sorry Colonel, I've just realised that i was chasing a light house beam, we could never defend that.

Obs

[redsocks]

Redsocks

Ian Ridpath may still be vindicated with his light house theory.
Sorry Colonel, I've just realised that i was chasing a light house beam, we could never defend that.

Obs

Hear what you are saying Lt Col and yes it was pretty stupid........you ever heard of the word "smoke screen" Charles?.... trouble is it may take over your whole life......you know the airmen will have to join in as well to give it some weight........


Redsocks

[Observer]

Redsocks

We could make this into a play, will you write the script, but i want production rites.

Obs

[redsocks]

Redsocks

We could make this into a play, will you write the script, but i want production rites.

Obs

Yeah 50/40 sounds good, any other takers to make a few quid just think of the chat show/docu possibilities!!


Redsocks