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  • FIRST POST
    • Robin9
    • By Robin9 24th May 19, 8:46 AM
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    Robin9
    Wireless Radio Installation CH70 Issues
    • #1
    • 24th May 19, 8:46 AM
    Wireless Radio Installation CH70 Issues 24th May 19 at 8:46 AM
    My church has a wireless lapel/hand mic installation operating on CH70 - our mics are around 770 Mhz. We hold a PMSE license for these frequencies.The speakers are hardwired .Original installation 2013.

    Since 2016 we have experienced brief bursts of "noise" - quite unpredictable.

    I am aware of the withdrawal of CH70 by May 2020 and we are registered for the grant - we expect to do a complete replacement and then operate on CH38.

    Could this issue be 4G related - we have two masts within 1/2 km. ?

    Will the change to CH38 solve the problem.?
    Never pay on an estimated bill
Page 1
    • Norman Castle
    • By Norman Castle 24th May 19, 7:18 PM
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    Norman Castle
    • #2
    • 24th May 19, 7:18 PM
    • #2
    • 24th May 19, 7:18 PM
    Could you tune a radio to the ch38 frequency to check for interference?
    Don't harass a hippie. You'll get bad karma.

    Never trust a newbie with a rtb tale.
    • Robin9
    • By Robin9 25th May 19, 6:47 AM
    • 4,316 Posts
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    Robin9
    • #3
    • 25th May 19, 6:47 AM
    • #3
    • 25th May 19, 6:47 AM
    Thank you for the suggestion - however to change from CH70 to CH38 means a complete change of transmitter and receiver which are made specific to the channel
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    • Biggus Dickus
    • By Biggus Dickus 25th May 19, 7:15 AM
    • 191 Posts
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    Biggus Dickus
    • #4
    • 25th May 19, 7:15 AM
    • #4
    • 25th May 19, 7:15 AM
    Thank you for the suggestion - however to change from CH70 to CH38 means a complete change of transmitter and receiver which are made specific to the channel
    Originally posted by Robin9
    • (Ch.70) Directly below 863MHz there is 4G mobile phone data transmission, there is no buffer so it is possible that some users may experience interference at the lower end of Channel 70 (around 863MHz).

    The alternative to shared spaces, deregulated or licenced, and generally considered the best option for churches is a ‘fixed site licence’, (aka ‘interleaved’ or ‘co-ordinated’ frequency Licence). These are individual radio frequencies specifically allocated to each radio system you have at your church location. They help ensure interference free operation. These frequencies will likely be dotted around the radio spectrum so it is advisable to obtain them first before purchasing radio mic equipment. However, as not all products will tune to all possible frequencies and research is required to find a clear frequency in your area we strongly recommend we administrate this process for you on a yearly basis.
    • Around £40 per Licence (renewed yearly) including DM administration.
    • Best option for interference free operation.
    • Radio Mics can only be used at the church.
    • Requires research to select a usable frequency in your area
    • Requires Radio Mic Systems capable of tuning to the licenced frequency – see our Choosing the Right Radio Mic equipment guide.

    https://www.dmmusic.com/radio-mic-frequencies-licensing/
    • Norman Castle
    • By Norman Castle 25th May 19, 7:26 AM
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    Norman Castle
    • #5
    • 25th May 19, 7:26 AM
    • #5
    • 25th May 19, 7:26 AM
    Thank you for the suggestion - however to change from CH70 to CH38 means a complete change of transmitter and receiver which are made specific to the channel
    Originally posted by Robin9
    I might be misunderstanding the equipment you have but am assuming it is a low power transmitter transmitting on 770mhz which any AM radio should be able to tune in to. If this works at your current frequency can you then use the same method to check the ch38 frequency. The only equipment you would need is an AM radio.
    Don't harass a hippie. You'll get bad karma.

    Never trust a newbie with a rtb tale.
    • thorganby
    • By thorganby 25th May 19, 8:02 AM
    • 235 Posts
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    thorganby
    • #6
    • 25th May 19, 8:02 AM
    • #6
    • 25th May 19, 8:02 AM
    Nobody can tell you if moving from PMSE Channel 70 to the new PMSE allocation of Channel 38 will solve your noise burst problem because it basically depends on the ability of the new equipment to reject unwanted interference that may swamp your radio mike systems receiver.

    Currently your radio mikes operating on Channel 70 (863-865 Mhz) are more likely to suffer irregular interference from 4G mobile handsets up link, rather than 4G base stations which transmit on higher frequencies than the mobiles up link.

    There is no point trying a radio mike system operating on Channel 38 at the moment because only when the 700 Mhz band is cleared of current users, will it then be used to expand 4G mobile.

    It is likely that the new PMSE equipment will be much better at rejecting unwanted signals than your current set up which was only required to reject low level signals from distant transmitters rather than locally generated higher powered transmissions from 4G mobile handsets e.g. mobile handsets often operate in close proximity i.e. in the same room using adjacent channels with no interference to each other.
    • Owain Moneysaver
    • By Owain Moneysaver 25th May 19, 10:51 AM
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    Owain Moneysaver
    • #7
    • 25th May 19, 10:51 AM
    • #7
    • 25th May 19, 10:51 AM
    The people on the Blue Room forum are pretty knowledgeable about radio mics and licencing

    https://www.blue-room.org.uk/index.php?showforum=3
    A kind word lasts a minute, a skelped erse is sair for a day.
    • virgo17
    • By virgo17 25th May 19, 11:07 AM
    • 743 Posts
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    virgo17
    • #8
    • 25th May 19, 11:07 AM
    • #8
    • 25th May 19, 11:07 AM
    I might be misunderstanding the equipment you have but am assuming it is a low power transmitter transmitting on 770mhz which any AM radio should be able to tune in to. If this works at your current frequency can you then use the same method to check the ch38 frequency. The only equipment you would need is an AM radio.
    Originally posted by Norman Castle
    770Mhz is a UHF frequency will need a scanner or other more specialised receiving equipment. 770 Khz is a low frequency which could be received on a basic LW/MW domestic receiver.

    This post relates to UHF frequencies which are co-existing between mobile phone networks and other (PA & Microphone) users, at present.
  • archived user
    • #9
    • 25th May 19, 8:00 PM
    • #9
    • 25th May 19, 8:00 PM
    I might be misunderstanding the equipment you have but am assuming it is a low power transmitter transmitting on 770mhz which any AM radio should be able to tune in to..
    Originally posted by Norman Castle
    Not a chance in hell of an AM radio of the type you're thinking of tuning into that. You seem to be confusing Kilohertz with Megahertz.

    ]Nobody can tell you if moving from PMSE Channel 70 to the new PMSE allocation of Channel 38 will solve your noise burst problem because it basically depends on the ability of the new equipment to reject unwanted interference that may swamp your radio mike systems receiver.
    by thorganby
    Yes they can, until I sold some of my gear I could, and I only do radio at a hobby level as a radio amateur.

    To the OP, what you need to do is find someone with a spectrum analyser or a receiver that covers the frequencies intended to be used, you may find if you contact your local amateur radio club they have someone who can help. They then need to visit the location, fire up the analyser/receiver, see what is being received by that on the frequencies you're intending to move to. The one I used to have, which was a budget level Rigol 815, would allow me to listen to the signals it received.
    • Heedtheadvice
    • By Heedtheadvice 25th May 19, 9:59 PM
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    • 586 Thanks
    Heedtheadvice
    Interference from mobile phones (transmitters where you have no control over their use) and the like is a common problem for radio mics, hence reliable systems use those dedicated licensed frequencies mentioned in another post. These are generally well controlled to prevent interference.
    System design can also alleviate or prevent the interference. Often the problem is worst in built up or industrial areas where there are more transmitters in the local area and where there is sub optimal signal between mic and receiver.



    Does your receiver have an external antenna?
    If so is it just a simple dipole (straight stick like)/stub type?
    If so replacing with a directional antenna and moving closer to the mic transmitter might aleviate or even cure the problem.
    The uhf antenna stub types are often omni directional and can be replaced by difectional types, wideband suitable for channel 38 and 70(and those between) etc. so probably can be reused when you move channels. Your receiver manufacturer may even sell one. They improve your signal reception and help reject the interfering signal(s) on a directional basis.

    Cost often below £200.
    • Heedtheadvice
    • By Heedtheadvice 25th May 19, 10:05 PM
    • 1,203 Posts
    • 586 Thanks
    Heedtheadvice
    As an example only to give you an idea https://www.rock-tech.co.uk/cms/products/directional-active-uhf-antenna-470-870-mhz-all-uhf-channels-21-to-70?web-page-id=194
    is a powered one but there are also passive ones requiring no power......and other suppliers and manufacturers!!!
    • thorganby
    • By thorganby 26th May 19, 8:12 AM
    • 235 Posts
    • 189 Thanks
    thorganby
    Yes they can, until I sold some of my gear I could, and I only do radio at a hobby level as a radio amateur.

    To the OP, what you need to do is find someone with a spectrum analyser or a receiver that covers the frequencies intended to be used, you may find if you contact your local amateur radio club they have someone who can help. They then need to visit the location, fire up the analyser/receiver, see what is being received by that on the frequencies you're intending to move to. The one I used to have, which was a budget level Rigol 815, would allow me to listen to the signals it received.
    Originally posted by Tarambor
    They say that a little knowledge is a dangerous thing and your post illustrates this well.

    Had you bothered to read the rest of my post rather than trying to rubbish the first paragraph, you may have actually understood the OP's problem.

    Suggesting the use of a spectrum analyser now is a complete waste of time and effort!

    The existing equipment will be redundant within the next year and brand new equipment will be requisitioned to operate on their new PMSE license allocation on channel 38 when their currently allocated channel 70 will be cleared of current users and will then be used to expand 4G mobile.

    This new equipment is likely to be digital and very unlikely to suffer from the problems that the OP is currently experiencing on their old equipment.
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