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    "Empty barrels make the most noise."
    "God as my witness" - Jeremy Dewitte - Felon


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    Quote Originally Posted by com501 View Post
    Jesus H. Christ. Did anyone think to see how this one guy holds (or doesn't) the microphone? Talk about a rabbit hole...
    Bahahahhahahahahaahhahahahahahahah

    Oh god.... The memories....

    Car came in, deputy complains dispatch is saying they can't hear him, and he has to yell to be heard..... OK.... 'low audio on transmit'.....

    First thing, audio check. Literally pull mic off the clip, key it up, clear as day..

    I call the deputy into the shop and ask him if there were any other issues, trying to get clues.... Usually there's something else that clues you in, like 'radio turns off by itself sometimes' or something like that.


    So, I tell him it sounds great, I can bench it but it'll be about 30 mins, and I pull the mic off the clip about to detach it to take the radio out of the console......


    The deputy looks at me like I have 3 heads, and asked me how I got the microphone off so quick.

    *me, confused*

    Me: 'It just unplugs from the control head'

    Him : 'No, the other end'?


    Me: The mic? The end you talk into? It just slides out of the clip.

    Him : '........'

    Merealizing why his audio is low)

    Me: So, you pull the mic off the clip when you talk, right?

    Him : Well, I tried, but it didn't come off and I didn't wanna break it....

    Me: (oh god) (explains how mic goes on/off clip)




    I had just updated radios a couple months prior, and the microphone moved from the right side of the console to the left side of the console. He was trying to pull it back, not up, and didn't wanna break the new radio, and thought it was there PERMANENTLY, so he just keyed the mic, and was talking from 3 ft away...

    I had a similar issue of an officer talking into the back of a microphone, but that was more of an annoyance, hard to educate the old school idiots that slung the mic over the rear view.. It was concealed in the center console/cupholder in their unmarked cars. Completely low profile install with 1/4 wave mounted on INTERIOR rear deck behind heavy tint... and these guys would stretch the mic all the way out of the center console to the mirror... Ugh.
    Lets have a snack now, we'll get friendly later. You got a cat?

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    Is there an easy way to clean coffee off my screen? TW lmao

    I see this every day. Love the arms lengthers.
    Officer Ogletree Officer Ogletree Officer Ogletree SIR Officer Ogletree Officer Ogletree PLEASE!

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    Surely their time would be better spent going out on shift with the West End guy and take a photo of the microphone he has hanging from the interior mirror?

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    I have similar microphone stories, and I wrote them up as training issues. That made everybody happy.

    But, for Officer Mumbles and Officer Bellows, the guys that know they are doing it wrong and don't give two skips, I'd put a dynamic compressor in line with the repeat audio if it was possible.
    Bow wow wow yippie yo yippie yay

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    Hams around Mexico City got a new fashion: add mic a preamplifier to VHF and UHF radios, so they can boost their volume and so improve their coverage. Now distortion is everywhere.
    Juan Carlos
    KM4NNO

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    Really Wodie Everyone knows the further away you are from the other guy the louder you have to talk.

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    Quote Originally Posted by Notarola View Post
    The repair guys are the local contractor for maintaining several local(municipal) systems.

    I did not argue anything I just let them explain the complexity of the issue to me. My general opinion of the technical explanation supplied is this. BS baffles brains and technobable sounds impressive but is pure garbage. EM36 they believe that they have a handle on the situation and the mush they supplied is really what they believe is wrong.

    I have my own theory on the issue and strangely enough it matches Com501s conclusion, specifically this is a operator error and not a system one.

    Ill be following this as it progresses and will update on anything new.
    Have they actually duplicated this problem or are they trying to work with the theory?

    Usually multi path is highly variable. Exceptions are when you have a fixed reflecting object like a metal garage door or a nearby water tank.

    But I cannot recall a case where the modulation was entirely sucked out. It would seem the incident and reflected signals are going to track in frequency but not phase. If it is digital, yes the waveform will distort and BER will rise. But FM, should be audible because the phase "notch" will be fixed at a specific range of audio frequency.

    I don't buy that spinning an antenna element is going to make a measurable difference in recovered audio. The phase delay will be minuscule. Maybe they have an HDTV broadcast engineer looking at this.

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    Quote Originally Posted by Wodie View Post
    Hams around Mexico City got a new fashion: add mic a preamplifier to VHF and UHF radios, so they can boost their volume and so improve their coverage. Now distortion is everywhere.
    In the late 70's when low band was still in heavy commercial use, I experimented with deviation on a school bus system. Back then, as now, everybody complained about coverage, but they either didn't have the money, or didn't want to spend the money, to improve their coverage. I was just supposed to wave my hands, tighten a few screws, do some very precise alignments, and magically coverage would suddenly explode to magnificent distances with perfect clarity. Except it never did.

    We were allowed +/-5kc, but I noticed these Mocom 10 mobiles accepted almost double that without distortion from my service monitor. Motracs and Mocom 70s would only go to about 8kc, and since those were in this system as well, that set the high water mark for deviation. On their next PM, I proceeded to bump up the deviation on every radio to about six and a half knowing that dull mic elements, and user mic techniques, would ultimately keep most radios well within the legal limits.

    But OMG, what a wonderful change it made for the customer. It got me huge accolades. Their supv called my boss to tell him how great I was blah blah blah, the system never sounded better blah blah blah thank you thank you thank you blah blah blah. Okay. I kept that one under my hat, but quietly started bumping up all the cop shops, taxi cabs, and every simplex low bander I had, and got similar results.

    I settled on 6.5kc as my limit knowing that (A) we were out in the country with no adjacent channel users, (B) back then most systems used auto-puke, not PL, so they were essentially CSQ with no cochannel users, and (C) they were all low to the ground systems surrounded by the forests of the Michigan UP and the Great Lakes. If I'm not hearing anybody else out there, nobody is hearing them. Let these people get that extra couple miles out of their radios.

    When I moved south to Detroit where systems were moving to UHF repeaters in dense RF environments with multiple cochannel and adjacent channel users, I had to tame my game, and come up with another plan. That's when I started making my own RC time constant compressor circuits to flatten out the dynamic range and get it to its legal max. Motorola was going in the same direction with their IDC circuits in the Micor and the Maxar which were just coming out. OTOH, GE was staying au natural, and many many Mastr, Mastr II, Mastr II Pro mobiles became hosts to my mods. Fun times.
    Bow wow wow yippie yo yippie yay

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    RFI: They appear to be trying to fix a symptom rather than the root cause. I believe they have convinced themselves that this is a major technical issue and not something simple. Any differing opinions are not met with enthusiasm as I found out.

    The possibility of the multipath argument fails as the unit is mobile thus the mobile to site path would be constantly changing. Add to this other units occasionally in the same area dont have the issue. On a technical note looking at the RF spectrum and the incoming signal would show the level drop or even the cyclic phase cancellation if that was the issue. For it to affect just the detected audio would require a set of circumstances that become mathematically impossible as you pointed out.

    There is nothing locally that could be a cause of RFI. I did do a drive by with my test hardware and the input to the repeater range is clean with the nearest in use freq being 945Khz and about 7 miles (a farm) away.

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    SIGH..........

    IMG_1576.jpg
    Officer Ogletree Officer Ogletree Officer Ogletree SIR Officer Ogletree Officer Ogletree PLEASE!

    Sarjint I'm asking...no I'm DEMANDING a Lieutenant....Or a supervisor that outranks him....J Dewitte.


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    Oh I posted too soon. this was the speaker wiring off the accessory connector. Took off the tape gobs. NIIIIIICE! Extra 2' of speaker wiring went to nowhere and was just cut off.
    Speaker could have shorted to ground at any time!
    IMG_1577.jpg
    Officer Ogletree Officer Ogletree Officer Ogletree SIR Officer Ogletree Officer Ogletree PLEASE!

    Sarjint I'm asking...no I'm DEMANDING a Lieutenant....Or a supervisor that outranks him....J Dewitte.


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    It appears that these guys don't have basic install tools or supplies. A roll of electrical tape and a screwgun? That's it? I'll donate a bag of butt connectors and a crimp too.
    "God as my witness" - Jeremy Dewitte - Felon

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    Improper tools does not justify that mess. Most of us would acknowledge an attempt to do the job professionally even without the correct tools. The 2' of extra wire is the sloppiness we are seeing over and over. IF the excess wires had been trimmed back and the connections properly/neatly done I might have given the installer the benefit of the doubt but this stuff is totally unacceptable.

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    Is not happening anymore. It is going to take 10 years to clean this stuff up!
    Officer Ogletree Officer Ogletree Officer Ogletree SIR Officer Ogletree Officer Ogletree PLEASE!

    Sarjint I'm asking...no I'm DEMANDING a Lieutenant....Or a supervisor that outranks him....J Dewitte.


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    Quote Originally Posted by Bill_G View Post
    In the late 70's when low band was still in heavy commercial use, I experimented with deviation on a school bus system. Back then, as now, everybody complained about coverage, but they either didn't have the money, or didn't want to spend the money, to improve their coverage. I was just supposed to wave my hands, tighten a few screws, do some very precise alignments, and magically coverage would suddenly explode to magnificent distances with perfect clarity. Except it never did.

    We were allowed +/-5kc, but I noticed these Mocom 10 mobiles accepted almost double that without distortion from my service monitor. Motracs and Mocom 70s would only go to about 8kc, and since those were in this system as well, that set the high water mark for deviation. On their next PM, I proceeded to bump up the deviation on every radio to about six and a half knowing that dull mic elements, and user mic techniques, would ultimately keep most radios well within the legal limits.

    But OMG, what a wonderful change it made for the customer. It got me huge accolades. Their supv called my boss to tell him how great I was blah blah blah, the system never sounded better blah blah blah thank you thank you thank you blah blah blah. Okay. I kept that one under my hat, but quietly started bumping up all the cop shops, taxi cabs, and every simplex low bander I had, and got similar results.

    I settled on 6.5kc as my limit knowing that (A) we were out in the country with no adjacent channel users, (B) back then most systems used auto-puke, not PL, so they were essentially CSQ with no cochannel users, and (C) they were all low to the ground systems surrounded by the forests of the Michigan UP and the Great Lakes. If I'm not hearing anybody else out there, nobody is hearing them. Let these people get that extra couple miles out of their radios.

    When I moved south to Detroit where systems were moving to UHF repeaters in dense RF environments with multiple cochannel and adjacent channel users, I had to tame my game, and come up with another plan. That's when I started making my own RC time constant compressor circuits to flatten out the dynamic range and get it to its legal max. Motorola was going in the same direction with their IDC circuits in the Micor and the Maxar which were just coming out. OTOH, GE was staying au natural, and many many Mastr, Mastr II, Mastr II Pro mobiles became hosts to my mods. Fun times.
    Undoubtedly the statute of limitations have run out!

    Major Edwin Howard Armstrong would applaud your efforts in making FM work the way he intended it to be!

    You can never have enough FM with FM.

    Actually I did something similar to my narrow band ICOM IC-4008A FRS radios. I found there was a sweet spot in the OAB bandwidth and exploited it by bumping them up closer to 4 KHz so they would work spiffy with my Saber GMRS radios.

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    Quote Originally Posted by Notarola View Post
    RFI: They appear to be trying to fix a symptom rather than the root cause. I believe they have convinced themselves that this is a major technical issue and not something simple. Any differing opinions are not met with enthusiasm as I found out.

    The possibility of the multipath argument fails as the unit is mobile thus the mobile to site path would be constantly changing. Add to this other units occasionally in the same area dont have the issue. On a technical note looking at the RF spectrum and the incoming signal would show the level drop or even the cyclic phase cancellation if that was the issue. For it to affect just the detected audio would require a set of circumstances that become mathematically impossible as you pointed out.

    There is nothing locally that could be a cause of RFI. I did do a drive by with my test hardware and the input to the repeater range is clean with the nearest in use freq being 945Khz and about 7 miles (a farm) away.
    There is another possibility. Someone does not like the guy who is having the audio problem and they are "mashing the button" when he talks.

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    Quote Originally Posted by Wodie View Post
    Hams around Mexico City got a new fashion: add mic a preamplifier to VHF and UHF radios, so they can boost their volume and so improve their coverage. Now distortion is everywhere.
    They are trying to get that fancy P25 Vocoder performance.

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    Quote Originally Posted by RFI-EMI-GUY View Post
    Undoubtedly the statute of limitations have run out!

    Major Edwin Howard Armstrong would applaud your efforts in making FM work the way he intended it to be!

    You can never have enough FM with FM.

    Actually I did something similar to my narrow band ICOM IC-4008A FRS radios. I found there was a sweet spot in the OAB bandwidth and exploited it by bumping them up closer to 4 KHz so they would work spiffy with my Saber GMRS radios.
    I learned a lot about FM performance from those experiments. Over-deviation was also the quick way to earball align the IF chain in the field. It was banging the BW limits causing distortion in the recovered audio that in turn affected the squelch sensitivity. During the more recent narrowbanding effort, I was quick to learn how to maximize the dev in many models of radios. Most guys just clicked the box, wrote to the radio, and walked away. I aligned every radio concentrating on their base stations and repeaters first. My customers did not experience the widely predicted coverage loss. But, I wasn't charging just $8 a radio like our competition. I got to play janitor on lots of systems since those days. Just like the school bus, the amazing miraculous difference of good deviation continues to draw customer appreciation. It's kinda like being a highly regarded restaurant because I wash the dishes.
    Bow wow wow yippie yo yippie yay

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