Is 548.200MHz good to use for wireless TX/RX kits?

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dman

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#196322 27-May-2016 02:28

I'm looking at buying a 548.200MHz wireless kit, did some searching for Auckland, & came up with this:

http://www.qsl.net/zl1vfo/aktvchannels.htm

http://www.nzart.org.nz/info/technical/nz-tv-channel-frequencies/

Seems like 548.75MHz is carrying the audio for Sky Movies (Channel 30), being broadcast from the Remuera site (which is only a couple of suburbs over from myself).

Could this use of 548.75MHz be a big issue with a 548.200MHz wireless kit?? :-/ As it seems like that is very close! (or is 0.55MHz enough of a gap??)

Any other simple way I can check other than my googling attempts like I've been doing now?

https://www.youtube.com/c/SoundSpeeding

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#1560403 27-May-2016 03:03

Hmmmm....... this is a very curious map, not too sure what to make out of this, but does it mean 548.75MHz will not cause any interference problems once I get more than a few kilometers away from Remuera?

http://www.freeviewnz.tv/media/1120/remuera_standalone_freeview.pdf

https://www.youtube.com/c/SoundSpeeding

sbiddle

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#1560410 27-May-2016 07:08

You would possibly be breaking the law by using this equipment in NZ. You should really be using gear that uses an ISM band.

kiwiharry

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#1560417 27-May-2016 07:39

The info in your first post is obsolete. That technical information was relevant to analogue UHF transmissions. This is now superseded by Digital TV. DTV uses pretty much the entire 8MHz bandwidth of the TV channel.

Usage of frequencies between 510MHz and 686MHz is pretty much exclusively for TV broadcasting. There are secondary usage rights in parts of that band for wireless mics. All other types of transmissions are not licenced so would be illegal.

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mrdrifter

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#1560470 27-May-2016 09:34

I would suggest a good place to start would be http://www.rsm.govt.nz to understand what you can and can't do with the radio spectrum and where you may need to purchase license or broadcast rights.

Tracking down relatively high powered radio broadcasts and identifying their source can be quite straight forward.

dman

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#1560733 27-May-2016 14:23

We're not talking about a particularly powerful transmission here at all. The TX would be on the talent being sent to the RX being feed into a recorder (I have a Sound Devices 552 and Tascam DR680). A distance of only a few meters away.

I'm not setting up a tv station! :-o

That link I gave is for what ranges is safe to operate for wireless microphone sets, referencing 2015. So doubt it is out of date?!

https://www.youtube.com/c/SoundSpeeding

kiwiharry

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#1560813 27-May-2016 15:30

dman: We're not talking about a particularly powerful transmission here at all. The TX would be on the talent being sent to the RX being feed into a recorder (I have a Sound Devices 552 and Tascam DR680). A distance of only a few meters away.

I'm not setting up a tv station! :-o

That link I gave is for what ranges is safe to operate for wireless microphone sets, referencing 2015. So doubt it is out of date?!

The linked information contained on qsl.net and nzart are definatley out of date.

So are you using a wireless mic?

When you stated wireless TX/RX kit, that could be any one of a plethora of wireless transmitting equipment. You may not be wanting to setup a TV station but there are rules.

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dman

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#1560862 27-May-2016 16:33

kiwiharry:
The linked information contained on qsl.net and nzart are definatley out of date.

Oops! Sorry my bad, for some odd reason I thought I'd linked to http://www.ddready.co.nz/ as my first link. Which states as legal: "502-606 MHz and 622-698 MHz."

kiwiharry:
So are you using a wireless mic?

Yup! Wanting to use it for the purposes of film/video/etc

https://www.youtube.com/c/SoundSpeeding

Behodar

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#1560873 27-May-2016 16:55

I believe that this is the latest list: https://gazette.govt.nz/notice/id/2016-go446

502-694 MHz is available for audio/video only, up to -50 dBW (0.00001 W).

There is also a general licence for 510-606 MHz for radio microphones up to -3 dBW (0.5 W).

kiwiharry

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#1560897 27-May-2016 17:50

dman:
kiwiharry:
The linked information contained on qsl.net and nzart are definatley out of date.

Oops! Sorry my bad, for some odd reason I thought I'd linked to http://www.ddready.co.nz/ as my first link. Which states as legal: "502-606 MHz and 622-698 MHz."

kiwiharry:
So are you using a wireless mic?

Yup! Wanting to use it for the purposes of film/video/etc

OK. Yes wireless mics are able to be used in those 2 frequency bands. One way to test if frequency is clear is to only switch on the receiver. If you see RF, then depending on its level you could experience interference.

I'm assuming that because you asked about a specific frequency that your equipment is not frequency agile?

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knoydart

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#1560926 27-May-2016 19:43

This table gives you a graphical view of what is contained in the register of radio frequencies for digital television broadcasting.

If you use "DTV" in the channel search box, it will give you a nationwide set of licences, or you can put in a range of frequencies to see what is around.

richms

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#1560928 27-May-2016 19:52

If this is a beltpack and reciever type thing, I bought a cheap one and found it was unusable beyond about 5m from the reciever, and also when within about the same distance of a TV it was trashing some of the channels on it. Ended up swapping out for a 2.4GHz digital combo with better results, but some latency which might be a problem if you are using it in a live situation.

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dman

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#1560929 27-May-2016 19:58

kiwiharry:
OK. Yes wireless mics are able to be used in those 2 frequency bands. One way to test if frequency is clear is to only switch on the receiver. If you see RF, then depending on its level you could experience interference.

I'm in a tricky catch 22 however in that I can't test it out until I buy it.... (after it arrives from the USA)

And if it doesn't work due to too much interference then I'll be stuck with it!!

So thus I am trying to work out beforehand if it will work or not?!?!

kiwiharry:
I'm assuming that because you asked about a specific frequency that your equipment is not frequency agile?

Yup, frequency agile gear costs waaaay more!

I guess my core question comes down to this:

dman:

Seems like 548.75MHz is carrying the audio (but not the video) for Sky Movies (Channel 30), being broadcast from the Remuera site (which is only a couple of suburbs over from myself).

Could this use of 548.75MHz be a big issue with a 548.200MHz wireless kit?? :-/ As it seems like that is very close! (or is 0.55MHz enough of a gap??)

How much of an issue will Sky Movies (Channel 30) be for me with a 548.200MHz wireless kit? Is it a big enough gap away from it, or is this too close?

https://www.youtube.com/c/SoundSpeeding

richms

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#1560931 27-May-2016 20:01

SDR with one of the cheap TV tuners will show how clear the band is around the channel you want to use. If you are interested and in an area with other wireless mic users you can even sometimes hear their microphones with it. Well worth getting the cheap USB tuner to do SDR with if you have any interest at all in using the band. I had a cheap ebay wireless mic that had a few channels to choose from, but they were all within a few MHz of each other so pretty pointless

Richard rich.ms

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#1560934 27-May-2016 20:12

dman:

How much of an issue will Sky Movies (Channel 30) be for me with a 548.200MHz wireless kit? Is it a big enough gap away from it, or is this too close?

Given Sky shut down their analog channels in 2011 its hardly any issue

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kiwiharry

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#1561002 27-May-2016 21:56

Spyware:
dman:

How much of an issue will Sky Movies (Channel 30) be for me with a 548.200MHz wireless kit? Is it a big enough gap away from it, or is this too close?

Given Sky shut down their analog channels in 2011 its hardly any issue

Except Channel 30 is now a DTV channel for Igloo transmitting from Remuera.

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