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tube tech

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Posts posted by tube tech

  1. Posted

    check your local laws. in NM you can record a conversation if either party is aware of the recording, but if it is some random weirdo shouting at the world, you can't use it in court unless you shout something back at the random weirdo, turning a rant into a conversation.

    where all of this started: back in the 1960s recording devices were so noisy, and test equipment was so noisy, that you could cut and splice an audio tape and alter the content with little chance of being discovered. now they can measure tiny abrupt changes in noise reliably, but vacuum tube era laws live on.

  2. Posted

    a thing to know about IR illuminators: the ones shown above have large LEDs. this is a good thing. you can get an illuminator the size of the first one shown, with 96 tiny LEDs. the problem is, one of them gets hot and burns out, leaving 95 LEDs to suck up the same power source. the voltage across the remaining LEDs ratchets up a notch. the extra voltage burns out another LED, . the voltage across the remaining LEDs ratchets up another notch... pretty soon, you have a dozen surviving LEDs, which all burn up at once.

    big LEDs can handle more heat. the big LED illuminators operate for years. the ones with 4 vast LEDs in a 4 inch circle outlast the 48 LEDs in a 4 inch circle like a Chevy outlasts a Yugo.

    • Like 1

  3. Posted

    I find systems and packages to be unworkable. 8 identical cameras, 8 identical lenses - one size fits all in some world, but not mine

    Cameras do not gather information. lenses do that. bigger lenses have a better chance of getting more detail with less light than smaller lenses. bigger lenses are inherently harder to conceal. bigger lenses inherently require bigger cameras

    I prefer the small black square cameras that take 12mm X .5 thread lenses. unfortunately, they made a change a few years back and the newer cameras are less useful than the older cameras. they took the IR cut filters off the face of the sensor and moved it to the lens. if you pop the filter off the lens you get an excellent low light camera, and white trees on blue grass in the daytime.lrg_pinhole.jpg

    but not this camera. the cameras to get have a longer lens mount. you can't put a wide angle lens on this camera

    I have 24 of these in use, and 6 spares. some of them have been in use since 1996.

    https://i.ebayimg.com/images/g/jlEAAOSw5JhcyJ0K/s-l1600.jpg

    ( the system will not let me post that as an image )

    note the threaded area looks like a top hat or stovepipe. that gives you enough thread for a wide angle lens. put them up under the eaves, they are almost invisible.

    for detecting the presence of but not the identity of intruders: wide angle. for determining identity: long lenses at eye level. no distortion.

    with these 12mm x .5 lenses the focal length is essentially 1/10th of a 35 mm lens. 1.7 or 1.8 is a fisheye lens, 2.1 is wide angle, 2.8 is wider than usual, 6 mm is human eye like, anything higher is a telescope.

    DVRs: I prefer more 4 channel DVRs to one 16 channel monstrosity that puts postage stamp pictures on the monitor. I use Annke DVRs, which have NTP protocol, but it does not work. You need accurate time to make the evidence useful in court. NTP protocol is meant to do that.

  7. Posted

    maybe - search for peephole camera on ebay?

    I prefer Sony Super HAD CCD sensors. color in the daytime, B&W at night.

    note that funky junk CMOS cameras can be found in the same housing as 1080P CCD WiFi cameras. the higher end cameras all have CMOS sensors, and make claims about night vision and resolution not in keeping with past performance of CMOS sensors

    are you in the US, or elsewhere?

  9. Posted

    unlikely. IMHO the only cameras worth owning owning use Sony Super HAD CCD sensors. these produce a sharper, clearer, and and more color saturated image than older chips. if you watch a camera with a Sony Super HAD CCD sensor at twilight, looking at a truck with a red tripe and red lettering, the stripe and letters fade away. the black tires take on a faint green tinge, like dark woodland camouflage.

    if you want color at night you need to light it up like a football stadium.

  10. Posted

    1) video evidence must have a time stamp to be admissible in court

    2) if the clock is not accurate within a minute or so, the evidence will be inadmissible in court

    3) if the time on the video disagrees with the time on the camera,the evidence will be inadmissible in court

    IR wavelengths: almost any CCD camera will see in 850 nm light. very few cameras see 940 mm light. CMOS is useless with IR illumination.

    mount an 850 NM light on the building, pointed at your truck. do not buy the kind with 48 or 96 small LEDs. those small LEDs burn out fast if they get too much voltage. this reduces current draw, which raises voltage to the remaining LEDs, which burn out one by one. get the kind with 4, 6, or 8 LEDs the size of a fingertip. those large LEDs can dissipate extra heat.

    I would use an IP camera, a router in the truck with DD-WRT software that lets me use it as a bridge, a separate "solar battery" ( the battery is not solar; it attaches to a solar system ). I would connect the bridge to a wifi network in the building, and configure the camera to get NTP time. I would record with an NVR in the building.

    I tend to go berserk with this. all of my cameras are set up in a crossfire arrangement with other cameras. you are never on A camera, you are never on less than 2 and sometimes on 5.

  14. Posted

    I get solicitations to review equipment. The formula is, you buy the equipment from Amazon and review it. if you write a sufficiently glowing review, they refund your money. if you are not impressed just ship it back to Amazon for a refund.

    I sincerely doubt that this is an homage to my polysyllabic pettifoggery. more like, get sleazy people to write up things they would not buy without an incentive.

  15. Posted

    I'm looking for a different thing. Not a system. parts pieced together. I am an old school electronics tech, ergo a scrounger and cheapskate. my system is massive but inexpensive.

    most of my cameras are visible only if you look hard. my cheap camera of choice:

    https://www.ebay.com/itm/700TVL-CMOS-Wired-Mini-Micro-CCTV-Security-Camera-Wide-Angle-3-6MM-Lens/174344059684

    I use these lenses:

    https://www.ebay.com/itm/CCTV-1-8mm-Camera-Security-Lens-170-Degree-Wide-Angle-CCTV-IRCUSN-sh/313260112768

    https://www.ebay.com/itm/1-3inch-1-8mm-170-Degree-Wide-Angle-Black-CCTV-Lens-for-CCD-Security-Box-Camera/272594964981

    https://www.ebay.com/itm/2-5mm-MTV-CCTV-FPV-Camera-Lens-CL-1180/114168086394

    wide angle lenses are far more useful than narrower lenses.

    DVR: you absolutely must have NTP: the system sets its own time. if multiple DVRs show noticeably different times, the defense attorney can supress the evidence.

    I use 4 channel DVRs. even a small tv works with 4 images displayed, and you don't have to decipher location from 16 images on the screen.

    Bummer: DVR network interfaces don't work with any of my browsers in Linux. I can change settings but not view video.

  16. Posted

    my problem with those cameras is that you can't change the lens.

    if you are as old as I am, this is the best description I can provide: think of CCTV lenses as 1/10 the focal length of 35mm SLR lenses. these cameras appear to come with 4mm lenses, very similar to a 35mm focal length SLR lens.

     

    • in my experience the most useful lens is a 2.1mm. a 2.1 gives you area coverage, with a chance at recognizing the person in the image.
    • a 1.8 gives you vast area coverage, but it's "whodaheckizzat?" even if you know the person.
    • a 6mm gives you face recognition, if the guy stands in a certain spot for a while. you have to give them a reason to linger

    this system, like all canned systems, is one size fits all.

  17. Posted

    Quote

    Are there any system(s) currently available which have the capacity for:

    Frame rate to be adjusted

    Exposure times to be manually adjusted

    Image compression to be adjusted

    The footage to be recorded / downloaded in a number of formats.

    pro cameras. every camera at the price of a good used car. if you are not in the habit of saying "my other Learjet" - no.

    Secondly, Is anyone aware of any NVR systems which allow the user to set up the recording schedule.

    Quote

    Secondly, Is anyone aware of any NVR systems which allow the user to set up the recording schedule.

    the least expensive eBay DVR worth having can do this. it is unlikely that NVRs did not keep the ability.

  22. Posted

    Start with a proof of concept demonstration

    I would start with an IP camera that displays the focal length. temporarily mount it where you think you might want surveillance cameras, adjust zoom to suit and document for replay. determine needs before committing cash, sell management on more.

    if you get the coverage you need, and you don't need to PTZ all cameras, get cheap wired cameras, wire them to a DVR in the barn, and feed that to a wireless bridge. they come with either 6mm lenses or 2.1s.  I have a pile of unused 6mms. use the focal length determined with the zoom lens above to order lenses off ebay.

    here in the states you must have the DVR time and date accurate or the opposing lawyer gets the evidence banned from court. this means you need NTP capability. all cameras sync themselves to your national time standard. disable the clocks on the IP cameras if you have them and use DVR NTP as the sole time source.

  23. Posted

    waves in monitor is typically a ground loop. one ground loop can affect many cameras. take all off line but one, then add them back one at a time until the ground loop shows up. try the camera that ground loops by itself

     

    ground loops are typically fixed with a video isolation transformer.

     

    I have a ground loop from a camera with a broken ground connection inside the camera. when it ground loops it takes out a second healthy camera on the same DVR.

     

    this is not a straightforward troubleshoot and fix situation.

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