Looking for: Singlechip FM audio transmitter, UHF band - Page 1
Forum section: electronics / rf-microwave

author: Yansi
author_rank: Super Contributor
timestamp: October 09, 2017, 07:18:17 pm
content: Hello and sorry for creating another part searching thread. This time I am interested if any UHF band audio FM single chip solution exists out there. I did some googling beforehand, but could not find a thing.There are plenty of VHF (broadcast band) FM transmitter chips, but I am more interested in the UHF band, especially where the wireless audio bands are (say 740-870MHz).I would be quite surprised if all those thousands of wireless audio sets would all be cobbled from rather discrete circuitry. On the other hand I do not think so that companies like Shure, Sennheiser, Rode or such can do large enough volumes (no pun intended) they could afford to spin their own ASICs for this purpose.Thanks for any tips,Yan

author: MasterT
author_rank: Frequent Contributor
timestamp: October 09, 2017, 08:51:31 pm
content: SiLabs comes to my mind, sub 1GHz IC Si4432 & Si4463. It's transmits digital kind of modulation, though if you signature is correct and you familiar with uCPU it should not be a problem to code/decode audio traffic in 256 kbps. You may get module Si4432 for about $3 on aliexpress, just pay attention to frequency band, most common 433, and you have to search 868 or 915 MHz range.

author: Yansi
author_rank: Super Contributor
timestamp: October 09, 2017, 09:19:20 pm
content: Sorry, I need FM AUDIO. Not FSK.Digital unfortunately not applicable this time here as I want to interface existing analog systems in place.

author: BigBoss
author_rank: Regular Contributor
timestamp: October 09, 2017, 09:34:56 pm
content: Quote from: Yansi on October 09, 2017, 09:19:20 pmThis frequency band is reserved for TV Broadcasting only ( LTE in some countries) and transmitting something in this bandbrings absolutely a fine.Therefore you cannot find any device to transmit for this band.

author: Yansi
author_rank: Super Contributor
timestamp: October 09, 2017, 10:12:08 pm
content: Please keep yerr concerns of fines for yerrself, if you don't have anything to say to the topic, please.In our country it is LEGALY ALLOWED to use wireless microphones anywhere from 470 up to 690MHz (DVBT band), 694 up to 790, 823 to 832 and 863 to 865MHz. LTE is NOT present within these ranges. maximum ERP mainly 50mW maximum, depends on application and specific UHF band.So if you know NOTHING about our local legislatives, please stick to the topic.Not many things can piss me off more like somebodys unqualified concerns about others getting fines.Sorry for being rude, but, well.. uh. Don't do this!EDIT: //it seems you don't know even your own local legislative, see below//

author: Yansi
author_rank: Super Contributor
timestamp: October 09, 2017, 10:16:08 pm
content: I also encourage you to find France in this list and watch for yourself, where you can transmit.https://www.apwpt.org/downloads/handoutfrequencies2015.pdfGenerally, the shared operation in the DVBT band is preferred option for professional use, as that allows usually for most ERP (50mW typical).PS: Our country is not in that list, so don't bother to try looking for it.//EDIT: Corrected to the correct country.

author: Richard Crowley
author_rank: Super Contributor
timestamp: October 09, 2017, 10:27:24 pm
content: @Yansi yes, you are being RUDE when you attack people who are trying to help you.Since you appear to have deliberately disguised what country you are in ("00"), we have no clue.In many regions of the planet 700-800 Mhz gets into some sensitive public safety bandspace.And you do yourself no favors by giving only vague references to " existing analog systems in place"

author: Yansi
author_rank: Super Contributor
timestamp: October 09, 2017, 10:39:14 pm
content: I think that the question was very clear. I did not ask for anyone's concerns about getting fines (not your business anyway) and I think the country is pretty irrelevant. Frequencies were specified, I was not asking anyone to check if I can or can't transmit there.I also think it is pretty irrelevant to what equipment I will be interfacing to, as the frequencies this equipment operates was specified above (again) and I am pretty sure about the legal side of the thing.So do you still think it is relevant in this topic to deal with the local legislative in this topic? I do not think so.That is like asking for A, but you start screaming at me that B is illegal, while even C is pretty legal to do. Let me tell you that I have a very big dislike for this kind of off topic discussion.//EDIT: A very quick search reveals that even in the USA it is perfectly legal to transmit in parts of the TV broadcast bands in a licensed or unlicensed manner. For example:https://www.fcc.gov/general/wireless-microphones-0Bottomnote: While all professional wireless services throughout the world sit almost at the same bands, one would expect, that specialized circuitry is being made to cover all of that range. But as well may be not, due to the manufacturing volumes being quite low.

author: xaxaxa
author_rank: Regular Contributor
timestamp: October 11, 2017, 03:32:08 am
content: The ax5043 sells for about $3 on digikey and can do analog fm transmit and receive:http://www.onsemi.com/pub/Collateral/AND9313-D.PDFThe main downside is you have to configure it over spi.

author: Yansi
author_rank: Super Contributor
timestamp: November 10, 2017, 10:20:27 am
content: The AX5043 hack seems very interesting. The appnote is rather shy on detailed information, but may be worth a try. Thank you for your answer, this one was very helpful.

author: Mjolinor
author_rank: Frequent Contributor
timestamp: November 10, 2017, 10:29:03 am
content: Quote from: Yansi on November 10, 2017, 10:20:27 amI sort of thought they would all be helpful to someone. It is good to remember that this thread is public and therefore available to anyone searching for a similar solution so warnings of things around the subject are 100% relevant. There is absolutely no need to splatter the thread with posts about how you don't like it, that just makes it harder for someone to filter the information they need and more often than not results in another post on the subject.

author: Yansi
author_rank: Super Contributor
timestamp: November 14, 2017, 10:20:35 am
content: What else would you expect other than reposting, if this thread contains only 1 reply related to what was asked for, rest not related? I think that would be pretty expected result.

author: 4CX35000
author_rank: Regular Contributor
timestamp: November 14, 2017, 11:38:05 pm
content: Quote from: Yansi on October 09, 2017, 07:18:17 pmI don't think there are any dedicated IC's. Most analogue UHF TV modulators used on satellite receivers and video recorders, took the base band video were the FM sound at circa 6 MHz was already modulated or IF input at 35 MHz and mixed V+S together up to the UHF band.I suppose you could look at the same route and use a VHF modulator and mix it up to the UHF channel your using. One idea could be to find an old satellite receiver and remove the modulator and use that to get into the UHF channels without the hassle of designing a UHF mixer/amplifier stage.Probably easier to design using a off the shelf FM modulator chip set at a low frequency with a Mini-Circuits mixer and find a oscillator unit or even a IC to control the frequency output.As for the manufacturers, they are probably doing the same as I describe above were they modulate at a low frequency and mix it up to UHF.