HFU HF Underground

Loggings => VHF/UHF Logs, including satellites and radiosondes => Topic started by: R4002 on May 06, 2020, 1352 UTC

Title: 49 MHz Room Monitor / Open Mic With Some Serious Range 49.830 MHz
Post by: R4002 on May 06, 2020, 1352 UTC
49.83 MHz, pretty wide signal (sounded good on 49.825 MHz and 49.835 MHz in addition to 49.830 MHz).  I was using a VHF high band 1/4 wave antenna, which is certainly not the best antenna.  Noted at least part of the signal on 49.840 MHz too. 

https://youtu.be/sJizl4V45sA (https://youtu.be/sJizl4V45sA)

It sounds like somebody has a room monitor just on, you can hear a TV or radio in the background...at 0:59 or 1:00 in you can hear somebody say "oh you ready?".  More chatter around 1:30 and 1:40.  Interestingly enough, my scanner actually decoded too different CTCSS tones - 192.8 Hz and 196.6 Hz, on frequency. 
Title: Re: 49 MHz Room Monitor / Open Mic With Some Serious Range 49.830 MHz
Post by: sat_dxer on May 06, 2020, 1417 UTC
Will never understand why people get indignant about eavesdropping on 46 MHz cordless (or governments on cellular phones for that matter), but feel right at home about leaving a baby monitor bug on 24/7.
Title: Re: 49 MHz Room Monitor / Open Mic With Some Serious Range 49.830 MHz
Post by: R4002 on May 06, 2020, 2300 UTC
This seems to be a baby monitor used for an old folks' home or to monitor an invalid neighbor or elderly family member.  I did some more listening today with a better antenna.  Previously I was using a 1/4 wave VHF antenna tuned for the 140-160 MHz region, today I used a ProComm JBC1500 60" base-loaded CB antenna tuned for just below CB channel 1, 26.6 MHz or 26.7 MHz or so, as a 1/4 wave.  That makes almost a half wave at 49 MHz....and what a difference that made.  I could hear the 49.830 MHz signal nearly full scale for 1500+ feet in all directions, extending out to 3000 feet or so before the signal completely dropped off. 

I also was able to listen to it on a purpose-built 49 MHz FM walkie talkie - specifically a Maxon PC-50 (same thing as a RadioShack / Realistic TRC-512) 5-channel 49MHz handheld, with 49.83 MHz as Channel A.   I got took two more videos:

49.830 MHz FM range testing part 1 - https://youtu.be/BOfuappHakw

49.830 MHz FM range testing part 2 - https://youtu.be/KYPXazfNeMk