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[Nathan Salt]

Thanks Ike, I will look at adding those pads and some filters to my kit

Will go back to the salon and investigate their lighting

[Ray Aberle]

Ike,

As a quick reminder, if you follow this process / use this code, you can avoid those long ugly URLs!

Simply type:

[url=yourURLhere]The Clickable Link[/url]

So, [url=www.kelcema.com]Kelcema Audio[/url] yields Kelcema Audio

I find it easy to do as I am composing a post- I've ALREADY copied my URL (web site address), so as I am typing, I just type [url= then hit "paste" to get my URL in there. Close bracket ] -- type my text for the link, and then type [/url].  Takes just a few seconds longer but makes the posts a lot easier to read.

(There is a Insert URL button in the post "options" area above the new message field, but I always forget which one it is, so I just do it manually.)

Thanks for listening!

-Ray

[Henry Cohen]

That reminds me, I forgot to mention filters. Here's some info about that from the RF Venue site . . . Lectrosonics also sells band-specific filters, and Professional Wireless sells 470-616 MHz ones http://www.professionalwireless.com/product/uhf-in-line-filter-new-range/

A bandpass filter on the receiver does nothing to mitigate in band (co-channel) interference, which is the case with LED RFI. Transmitter out of band interference (receiver in band interference) can only be prevented at the source, with either a bandpass filter on the actual transmitter, or proper RFI circuit and shielding design on unintentional radiators.

[Jean-Pierre Coetzee]

Do you know what is happening with TV channels in your area? I know that the entire 470-516 band is covered by TV channels in our area(not an issue indoors and the fact that nobody sells units in that range here) and if you were outdoors in an elevated area you might have some issues finding an open channel.

[Andrew Broughton]

A bandpass filter on the receiver does nothing to mitigate in band (co-channel) interference, which is the case with LED RFI. Transmitter out of band interference (receiver in band interference) can only be prevented at the source, with either a bandpass filter on the actual transmitter, or proper RFI circuit and shielding design on unintentional radiators.

I assume (like usual) I'm just misunderstanding you, but it sounds like you disagree with James (from the above article) and Jason (in a post to me) who both suggest attenuating the input to the receiver may help the situation?

[Henry Cohen]

I assume (like usual) I'm just misunderstanding you, but it sounds like you disagree with James (from the above article) and Jason (in a post to me) who both suggest attenuating the input to the receiver may help the situation?

I don't disagree with James or Jason at all; they're absolutely correct. They were talking about broadband attenuation at the receiver input and raising the transmitter RF power to improve CNR, as well minimizing the chance the RF noise floor might saturate the receiver front end. This is the only effective measure for reducing the detrimental effects of inband / co-channel interference.

What I was talking about with respect to bandpass filtering, was that placing a BPF at the receiver input will do nothing to reduce the detrimental effects of inband / co-channel interference, since it's permitting the frequency range in question to pass with both the desired and unwanted RF energy. The only way to prevent the unwanted inband RF energy from being generated in the first place, is to treat the source of the RFI.

[Ike Zimbel]

I don't disagree with James or Jason at all; they're absolutely correct. They were talking about broadband attenuation at the receiver input and raising the transmitter RF power to improve CNR, as well minimizing the chance the RF noise floor might saturate the receiver front end. This is the only effective measure for reducing the detrimental effects of inband / co-channel interference.

What I was talking about with respect to bandpass filtering, was that placing a BPF at the receiver input will do nothing to reduce the detrimental effects of inband / co-channel interference, since it's permitting the frequency range in question to pass with both the desired and unwanted RF energy. The only way to prevent the unwanted inband RF energy from being generated in the first place, is to treat the source of the RFI.

Yeah, but...if the interference is so broadband that it covers the whole range from say 150MHz to 1GHz, a band pass filter will reduce the amount of overall noise that's bombarding your antennas and Rx front end, no?

[Cameron Stuckey]

Yeah, but...if the interference is so broadband that it covers the whole range from say 150MHz to 1GHz, a band pass filter will reduce the amount of overall noise that's bombarding your antennas and Rx front end, no?

Yeah, but... what is being accomplished for an example tuned frequency(in red) with a bandpass filter? Co-channel interference, direct overlapping noise, cannot be fixed except for at the source of that interference. It doesn't matter how much out of band, non-overlapping noise, you are able to eliminate.

[Justin Goodman]

Do you know what is happening with TV channels in your area? I know that the entire 470-516 band is covered by TV channels in our area(not an issue indoors and the fact that nobody sells units in that range here) and if you were outdoors in an elevated area you might have some issues finding an open channel.

I don't believe that even every TV channel broadcasting on every one of their DTV subchannels could produce a noise floor that high. I'm not an RF specialist by any means, but when I overlay scans into WWB and then go in and block out local TV stations, I see some peaks obviously within those ranges, obviously, but it's hardly across the entire spectrum like the OP's image.

[ProSoundWeb Community]