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Thread: what am i hearing?

  1. #1

    Default what am i hearing?

    Hey, so i am brand new to amature radio. i dont have a license to operate (and i havnt been), and i find alot of this stuff very confusing. i've picked up a cheap leixen vv898 chineese mobile and have just been using it to play around and hear what i can hear- eves dropping on the fire dept frequencies, cab frequencies, delivery driver disbatch frequencies, repeater frequencies, ect. my radio is UHF/VHF capable.

    on the VHF frequencies i often get channels that are always transmitting, but all i hear is static, just constant, unbroken static. howcome? why would there be channels that are always open, but nothing is ever said?

    also on VHF frequencies, i often pick up very loud, constant transmissions of what i can only describe as what sounds like a transport engine, or a very low pitched machinegun fire- constant, very rapid 'boh boh boh boh boh boh' sounds. it never realy changes. what is this? im assuming its some sort of digital signal?

    then today on the UHF frequencies (which i rarly ever receive anything on) i picked up this (sounds in question start at the 0:50 mark): https://youtu.be/rp4mo9FdZ4c
    what exactly is that?

  2. #2
    GTGallop's Avatar
    Join Date
    Jul 2014
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    Question - On your radio, what does pushing the # button do? Is that advancing the frequency? Also it sounds like you have your squelch turned way down / off. And lastly, generally speaking, what region of the world are you in?
    KG7NDC

  3. #3

    Default

    The motorboat sound is characteristic of one of the digital modes - often the Motorola system one, and digital buzz saw noises are other digital or data modes. A constant empty carrier could be just that, but more likely to be an internal spurious birdie - produced inside your radio. Test this by removing the antenna. If it goes, it's real carrier, and if it remains, it comes from inside. Blank carriers are reasonably common, and the real receivers get opened and closed by sub audible or tone signals - but if you never hear anything, they're phantom images and can be skipped. Digital is becoming common wherever in the world you are. My friend is in the Gambia, they still live in corrugated tin houses, have little to eat - but have digital radio and the internet.

  4. #4

    Join Date
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    Hello fojaxx,

    What you haven't mentioned is the time of day or night that you're hearing these signals. If it's night time using the 433 MHz frequency, it could be the JT-65 Digital Signaling used for Amateur Radio Moon Bounce operations and since your transceiver is set up for Analog ONLY these signals cannot be decoded by your receiver section.

    As GT has pointed out, it sounds like your Squelch Control is set at OFF which would drive most people nuts hearing the constant rushing noise. This is why the Squelch circuit was designed to eliminate the constant rushing noise coming through the audio stage and speaker. Setting the Squelch Level Up to cut off the noise till a Bona Fide Analog Signal is heard through the speaker. One thing you must remember, the UHF Ham Band 420 to 450 MHz uses multi-modes such as AM, FM, SSB, CW, RTTY, Digital FM Voice FDMA & TDMA and Digital Signaling PSK-31, JT65A, JT9, FT8, Olivia, Hellscriber and many more.

    Generally the 420 through 430 MHz portion is used for RF Linking Repeaters together, 430 to 440 MHz becomes a little bit more tricky since 432 MHz has been used by the Moon Bounce and SSB / CW crowd for decades but you should refer to the ARRL Band Plan for 70 cm which is more accurate. http://www.arrl.org/band-plan The 440 to 450 MHz is used for both Analog FM and Digital FM Voice Repeaters. And Oh BTW, here in the United States the Amateur Radio Community shares the 70 cm Band with the USAF so we have RF Power Limits of 50 W any where near our Coast Lines.

    Dan
    WA9WVX

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