On Sat, 5 Jun 2021 11:14:05 -0700 (PDT), Harry Dudley-Bestow <harry.dudleybestow@gmail.com> wrote:>Looking to build a sensible FM radio transmit/receive pair, designed for short range (10s of meters) and excellent audio quality. Making for personal use, so very flexible on operating frequency, BOM cost etc. > >Had a look in my go-to Art of Electronics (not enough detail) and tried to find an app note or something on the subject, no dice. Designs on the internet have no explanations alongside them and are far too optimised for low BOM count at expense quality of output. > >Anyone got recommendations for design resources on the subject?https://www.adafruit.com/product/1958 Making good DIY FM transmitters and receivers was difficult in the old days and it still is. You can Google pirate FM, Pirate radio and so on, because that's what they are.
FM radio design resources
Started by ●June 5, 2021
Reply by ●June 5, 20212021-06-05
Reply by ●June 5, 20212021-06-05
harry.dud...@gmail.com wrote: ==========================> Looking to build a sensible FM radio transmit/receive pair, designed for short range (10s of meters) and excellent audio quality.** Just one system ? Mono or stereo ? AC or battery powered ?> Making for personal use, so very flexible on operating frequency, BOM cost etc.** You are are aware of wireless mic systems for musical performances ? Most are variable frequency, wide band FM with "twin diversity" receivers on UHF. The latter is very important as single receivers work poorly indoors due to standing wave self cancellations. Building your own one sounds absurd ...... Phil
Reply by ●June 5, 20212021-06-05
On Saturday, June 5, 2021 at 5:26:32 PM UTC-7, palli...@gmail.com wrote:> harry.dud...@gmail.com wrote: > ========================== > > Looking to build a sensible FM radio transmit/receive pair, designed for short range (10s of meters) and excellent audio quality. > ** Just one system ? Mono or stereo ? AC or battery powered ? > > Making for personal use, so very flexible on operating frequency, BOM cost etc. > ** You are are aware of wireless mic systems for musical performances ? > Most are variable frequency, wide band FM with "twin diversity" receivers on UHF. > The latter is very important as single receivers work poorly indoors due to standing wave self cancellations. > > Building your own one sounds absurd > > > ...... PhilPhil: I just want to build one system. I know some FM use a difference signal for stereo but that sounds too complicated for my first project, so I'll just build two systems and operate them of different bands for L/R. The system will be USB powered on the transmit side, and battery powered on the receive side (I'll drill a hole in my headphones and tap off the battery). You are of course correct that it is absurd to build my own setup if the goal is to just get a working setup. But this is a learning project and so the journey is the important thing, not the destination! I will look into 'twin diversity' receivers for FM radio. Do you think I could avoid standing wave problems if I just occupied a huge bandwidth (say the whole 902-928MHz band)?
Reply by ●June 6, 20212021-06-06
On Sat, 5 Jun 2021 17:33:52 -0700 (PDT), Harry Dudley-Bestow <harry.dudleybestow@gmail.com> wrote:>On Saturday, June 5, 2021 at 5:26:32 PM UTC-7, palli...@gmail.com wrote: >> harry.dud...@gmail.com wrote: >> ========================== >> > Looking to build a sensible FM radio transmit/receive pair, designed for short range (10s of meters) and excellent audio quality. >> ** Just one system ? Mono or stereo ? AC or battery powered ? >> > Making for personal use, so very flexible on operating frequency, BOM cost etc. >> ** You are are aware of wireless mic systems for musical performances ? >> Most are variable frequency, wide band FM with "twin diversity" receivers on UHF. >> The latter is very important as single receivers work poorly indoors due to standing wave self cancellations. >> >> Building your own one sounds absurd >> >> >> ...... Phil >Phil: >I just want to build one system. I know some FM use a difference signal for stereo but that sounds too complicated for my first project, so I'll just build two systems and operate them of different bands for L/R. The system will be USB powered on the transmit side, and battery powered on the receive side (I'll drill a hole in my headphones and tap off the battery). > >You are of course correct that it is absurd to build my own setup if the goal is to just get a working setup. But this is a learning project and so the journey is the important thing, not the destination! I will look into 'twin diversity' receivers for FM radio. Do you think I could avoid standing wave problems if I just occupied a huge bandwidth (say the whole 902-928MHz band)?Alison knows sweet FA about RF and is one of the biggest trolls on this group - as you'll find out if you continue your exchange with him. Just thought I'd give you a heads-up on that little fact.
Reply by ●June 6, 20212021-06-06
Cursitor Doom = Shit for Brains Usenet Criminal. ==========================================> > >> > Looking to build a sensible FM radio transmit/receive pair, designed for short range (10s of meters) and excellent audio quality. > >> ** Just one system ? Mono or stereo ? AC or battery powered ? > >> > Making for personal use, so very flexible on operating frequency, BOM cost etc. > >> ** You are are aware of wireless mic systems for musical performances ? > >> Most are variable frequency, wide band FM with "twin diversity" receivers on UHF. > >> The latter is very important as single receivers work poorly indoors due to standing wave self cancellations. > >> > >> Building your own one sounds absurd > >> > >Phil: > >I just want to build one system. I know some FM use a difference signal for stereo but that sounds too complicated for my first project, so I'll just build two systems and operate them of different bands for L/R. The system will be USB powered on the transmit side, and battery powered on the receive side (I'll drill a hole in my headphones and tap off the battery). > > > >You are of course correct that it is absurd to build my own setup if the goal is to just get a working setup. But this is a learning project and so the journey is the important thing, not the destination! I will look into 'twin diversity' receivers for FM radio. Do you think I could avoid standing wave problems if I just occupied a huge bandwidth (say the whole 902-928MHz band)? >> Alison knows sweet FA about RF** ROTFL !!! Been dealing with it, hobby and professional, very much hands on, all my life. The OP is a trolling, know nothing fuckwit. You are such an hee hawing ass you can't possibly tell the difference. ..... Phil
Reply by ●June 6, 20212021-06-06
On 05/06/2021 11:01 pm, Harry Dudley-Bestow wrote:> On Saturday, June 5, 2021 at 2:54:46 PM UTC-7, Cursitor Doom wrote: >> On Sat, 5 Jun 2021 11:36:25 -0700 (PDT), Harry Dudley-Bestow >> <harry.dud...@gmail.com> wrote: >> >>> On Saturday, June 5, 2021 at 11:31:34 AM UTC-7, Ed Lee wrote: >>>> On Saturday, June 5, 2021 at 11:14:09 AM UTC-7, harry.dud...@gmail.com wrote: >>>>> Looking to build a sensible FM radio transmit/receive pair, designed for short range (10s of meters) and excellent audio quality. Making for personal use, so very flexible on operating frequency, BOM cost etc. >>>>> >>>>> Had a look in my go-to Art of Electronics (not enough detail) and tried to find an app note or something on the subject, no dice. Designs on the internet have no explanations alongside them and are far too optimised for low BOM count at expense quality of output. >>>>> >>>>> Anyone got recommendations for design resources on the subject? >>>> This should work: >>>> >>>> https://www.mouser.com/datasheet/2/268/microchip_technology_mchp-s-a0001247358-1-1738104.pdf >>>> >>>> But I haven't look too deeply into it. >>> Sorry Ed I failed to specify that my project must be designed using only classic RF components like our forefathers used, no all-in-one IC's allowed. >> Finally a purist! Welcome aboard! > Thanks for the recommendation amdx, I'll check it out. > > From looking around it looks like my main choices are quadrature detector and PLL demodulation on the receive side. For my taste the quadrature detection is better since it is made out of discrete inductor + capacitor to get the phase delay rather than a newfangled IC, but I can't seem to find out if it's possible to get good quality audio out of it. > Naively it seems to me that a large signal bandwidth compared to the IF would be the limiting factor, since that would push the phase shift out of the linear sin(x) = x region. Is my intuition correct here, and is it possible to get audio that is more or less indistinguishable to the kind you get over a copper cable? >In the old days before quadrature and PLL detectors some descrete "pulse count" discriminators were used at low-ish intermediate frequencies for high quality audio reproduction with fewer parts. Should be some 1960s designs online. I think you will find building the hifi micro-power transmitter will be much easier than building the matching receiver. piglet
Reply by ●June 6, 20212021-06-06
On Sunday, June 6, 2021 at 6:47:00 PM UTC+10, Cursitor Doom wrote:> On Sat, 5 Jun 2021 17:33:52 -0700 (PDT), Harry Dudley-Bestow > <harry.dud...@gmail.com> wrote: > > >On Saturday, June 5, 2021 at 5:26:32 PM UTC-7, palli...@gmail.com wrote: > >> harry.dud...@gmail.com wrote: > >> ========================== > >> > Looking to build a sensible FM radio transmit/receive pair, designed for short range (10s of meters) and excellent audio quality. > >> > >> ** Just one system ? Mono or stereo ? AC or battery powered ? > >> > Making for personal use, so very flexible on operating frequency, BOM cost etc. > >> ** You are are aware of wireless mic systems for musical performances ? > >> Most are variable frequency, wide band FM with "twin diversity" receivers on UHF. > >> The latter is very important as single receivers work poorly indoors due to standing wave self cancellations. > >> > >> Building your own one sounds absurd > >> > >Phil: > >I just want to build one system. I know some FM use a difference signal for stereo but that sounds too complicated for my first project, so I'll just build two systems and operate them of different bands for L/R. The system will be USB powered on the transmit side, and battery powered on the receive side (I'll drill a hole in my headphones and tap off the battery). > > > >You are of course correct that it is absurd to build my own setup if the goal is to just get a working setup. But this is a learning project and so the journey is the important thing, not the destination! I will look into 'twin diversity' receivers for FM radio. Do you think I could avoid standing wave problems if I just occupied a huge bandwidth (say the whole 902-928MHz band)? > > Alison knows sweet FA about RF and is one of the biggest trolls on this group - as you'll find out if you continue your exchange with him. Just thought I'd give you a heads-up on that little fact.Cursitor Doom knows very little about anything, but he's just as ill-informed about the depth of his ignorance as he is about everything else. He's also an even worse troll than Phil Alison - mainly because Phil Alison knows quite a bit audio (which does include FM radio) and devotes some of his tine to telling people about it. Cursitor Doom's "heads up" is just one more reminder that Cursitor Doom's head is firmly up his own backside. -- Bill Sloman, Sydney
Reply by ●June 6, 20212021-06-06
On Sun, 6 Jun 2021 11:53:22 +0100, piglet <erichpwagner@hotmail.com> wrote:>On 05/06/2021 11:01 pm, Harry Dudley-Bestow wrote: >> On Saturday, June 5, 2021 at 2:54:46 PM UTC-7, Cursitor Doom wrote: >>> On Sat, 5 Jun 2021 11:36:25 -0700 (PDT), Harry Dudley-Bestow >>> <harry.dud...@gmail.com> wrote: >>> >>>> On Saturday, June 5, 2021 at 11:31:34 AM UTC-7, Ed Lee wrote: >>>>> On Saturday, June 5, 2021 at 11:14:09 AM UTC-7, harry.dud...@gmail.com wrote: >>>>>> Looking to build a sensible FM radio transmit/receive pair, designed for short range (10s of meters) and excellent audio quality. Making for personal use, so very flexible on operating frequency, BOM cost etc. >>>>>> >>>>>> Had a look in my go-to Art of Electronics (not enough detail) and tried to find an app note or something on the subject, no dice. Designs on the internet have no explanations alongside them and are far too optimised for low BOM count at expense quality of output. >>>>>> >>>>>> Anyone got recommendations for design resources on the subject? >>>>> This should work: >>>>> >>>>> https://www.mouser.com/datasheet/2/268/microchip_technology_mchp-s-a0001247358-1-1738104.pdf >>>>> >>>>> But I haven't look too deeply into it. >>>> Sorry Ed I failed to specify that my project must be designed using only classic RF components like our forefathers used, no all-in-one IC's allowed. >>> Finally a purist! Welcome aboard! >> Thanks for the recommendation amdx, I'll check it out. >> >> From looking around it looks like my main choices are quadrature detector and PLL demodulation on the receive side. For my taste the quadrature detection is better since it is made out of discrete inductor + capacitor to get the phase delay rather than a newfangled IC, but I can't seem to find out if it's possible to get good quality audio out of it. >> Naively it seems to me that a large signal bandwidth compared to the IF would be the limiting factor, since that would push the phase shift out of the linear sin(x) = x region. Is my intuition correct here, and is it possible to get audio that is more or less indistinguishable to the kind you get over a copper cable? >> > >In the old days before quadrature and PLL detectors some descrete "pulse >count" discriminators were used at low-ish intermediate frequencies for >high quality audio reproduction with fewer parts. Should be some 1960s >designs online. > >I think you will find building the hifi micro-power transmitter will be > much easier than building the matching receiver. > >pigletWarum sagst du das, klein Piglet?
Reply by ●June 6, 20212021-06-06
On Sun, 6 Jun 2021 02:39:04 -0700 (PDT), Phil Allison <pallison49@gmail.com> wrote:> Cursitor Doom = Shit for Brains Usenet Criminal. > >========================================== >> >> >> > Looking to build a sensible FM radio transmit/receive pair, designed for short range (10s of meters) and excellent audio quality. >> >> ** Just one system ? Mono or stereo ? AC or battery powered ? >> >> > Making for personal use, so very flexible on operating frequency, BOM cost etc. >> >> ** You are are aware of wireless mic systems for musical performances ? >> >> Most are variable frequency, wide band FM with "twin diversity" receivers on UHF. >> >> The latter is very important as single receivers work poorly indoors due to standing wave self cancellations. >> >> >> >> Building your own one sounds absurd >> >> >> >Phil: >> >I just want to build one system. I know some FM use a difference signal for stereo but that sounds too complicated for my first project, so I'll just build two systems and operate them of different bands for L/R. The system will be USB powered on the transmit side, and battery powered on the receive side (I'll drill a hole in my headphones and tap off the battery). >> > >> >You are of course correct that it is absurd to build my own setup if the goal is to just get a working setup. But this is a learning project and so the journey is the important thing, not the destination! I will look into 'twin diversity' receivers for FM radio. Do you think I could avoid standing wave problems if I just occupied a huge bandwidth (say the whole 902-928MHz band)? >> > >> Alison knows sweet FA about RF > >** ROTFL !!! > >Been dealing with it, hobby and professional, very much hands on, all my life. > >The OP is a trolling, know nothing fuckwit.I rest my case.
Reply by ●June 6, 20212021-06-06
On Sun, 6 Jun 2021 04:26:51 -0700 (PDT), Bill Sloman <bill.sloman@ieee.org> wrote:>On Sunday, June 6, 2021 at 6:47:00 PM UTC+10, Cursitor Doom wrote: >> On Sat, 5 Jun 2021 17:33:52 -0700 (PDT), Harry Dudley-Bestow >> <harry.dud...@gmail.com> wrote: >> >> >On Saturday, June 5, 2021 at 5:26:32 PM UTC-7, palli...@gmail.com wrote: >> >> harry.dud...@gmail.com wrote: >> >> ========================== >> >> > Looking to build a sensible FM radio transmit/receive pair, designed for short range (10s of meters) and excellent audio quality. >> >> >> >> ** Just one system ? Mono or stereo ? AC or battery powered ? >> >> > Making for personal use, so very flexible on operating frequency, BOM cost etc. >> >> ** You are are aware of wireless mic systems for musical performances ? >> >> Most are variable frequency, wide band FM with "twin diversity" receivers on UHF. >> >> The latter is very important as single receivers work poorly indoors due to standing wave self cancellations. >> >> >> >> Building your own one sounds absurd >> >> >> >Phil: >> >I just want to build one system. I know some FM use a difference signal for stereo but that sounds too complicated for my first project, so I'll just build two systems and operate them of different bands for L/R. The system will be USB powered on the transmit side, and battery powered on the receive side (I'll drill a hole in my headphones and tap off the battery). >> > >> >You are of course correct that it is absurd to build my own setup if the goal is to just get a working setup. But this is a learning project and so the journey is the important thing, not the destination! I will look into 'twin diversity' receivers for FM radio. Do you think I could avoid standing wave problems if I just occupied a huge bandwidth (say the whole 902-928MHz band)? >> >> Alison knows sweet FA about RF and is one of the biggest trolls on this group - as yu'll find out if you continue your exchange with him. Just thought I'd give you a heads-up on that little fact. > >Cursitor Doom knows very little about anything, but he's just as ill-informed about the depth of his ignorance as he is about everything else. > >He's also an even worse troll than Phil Alison - mainly because Phil Alison knows quite a bit audio (which does include FM radio) and devotes some of his tine to telling people about it. > >Cursitor Doom's "heads up" is just one more reminder that Cursitor Doom's head is firmly up his own backside.The three worst trolls on this newsgroup are Bill Sloman (by some margin) followed by Phil Alison and Destitutedrugabuser. I believe they all come from Sydney, which no doubt goes a long way to accounting for this phenomenon; Sydney's lingua franca being outstanding in the English-speaking world for it's unashamed courseness. There's not a lot to be said in favour of the rest of the country, either, if the truth be told, but the Sydneyites are a special breed indeed when it comes to getting attention by *any* means. -- Britain: do the right thing and hand Australia back to China.
